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Gastrointestinal motility disorders in children: etiology and associated behaviors
Peeters, B.
Publication date 2013 Document Version Final published version
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UvA-DARE is a service provided by the library of the University of Amsterdam (https://dare.uva.nl) Download date:29 Sep 2021 GASTROINTESTINAL MOTILITY DISORDERS IN CHILDREN; ETIOLOGY AND ASSOCIATED CHILDREN; DISORDERS IN AND ETIOLOGY BEHAVIORS MOTILITY GASTROINTESTINAL
GASTROINTESTINAL MOTILITY DISORDERS IN CHILDREN; ETIOLOGY AND ASSOCIATED BEHAVIORS Babette Peeters Babette
Babette Peeters GASTROINTESTINAL MOTILITY DISORDERS IN CHILDREN; ETIOLOGY AND ASSOCIATED BEHAVIORS
Babette Peeters Cover: Chris Bor, ‘The gordian knot’ Gastrointestinal motility disorders in children; etiology and associated behaviors Thesis, University of Amsterdam, The Netherlands
The financial support for printing of this thesis by the following foundations and companies is gratefully acknowledged: Universiteit van Amsterdam, Nederlandse Vereniging van Gastroenterologie, De Club van 100 van de Poeppoli
Lay-out: Chris Bor, Medische Fotografie en Illustratie, AMC Amsterdam Printed by: Buijten & Schipperheijn, Amsterdam ISBN: 978-90-9027245-0
© B. Peeters, The Netherlands All rights reserved. No part of this publication may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photo copy, recording or otherwise, without the written permission of the author. GASTROINTESTINAL MOTILITY DISORDERS IN CHILDREN; ETIOLOGY AND ASSOCIATED BEHAVIORS
ACADEMISCH PROEFSCHRIFT
ter verkrijging van de graad van doctor aan de Universiteit van Amsterdam op gezag van de Rector Magnificus prof. dr. D.C. van den Boom ten overstaan van een door het college voor promoties ingestelde commissie, in het openbaar te verdedigen in de Agnietenkapel op vrijdag 18 januari 2013, te 12.00 uur
door Babette Peeters
geboren te Breda PROMOTIECOMMISSIE Promotores: Prof. dr. M.A. Benninga Prof. dr. R.C.M. Hennekam
Overige leden: Prof. dr. F. Boer Prof. dr. M.A. Grootenhuis Prof. dr. H.A. Heij Prof. dr. H.S.A. Heymans Prof. dr. E.E.S. Nieuwenhuis Prof. dr. F.A. Wijburg Prof. dr. A.J.P.M. Smout
Faculteit der Geneeskunde
Voor mijn ouders
CONTENTS
General introduction and outline of the thesis 5
Part I; Gastro-esophageal reflux disease
Chapter 1 Genome-wide linkage analysis in a multigenerational family identifies 21 new susceptibility regions for gastro-esophageal reflux disease on chromosomes 4, 12 and 14
Part II; Infantile hypertrophic pyloric stenosis
Chapter 2 Infantile hypertrophic pyloric stenosis: genetics and syndromes 39
Chapter 3 Seasonal variations in the incidence of infantile hypertrophic pyloric 75 stenosis in two Dutch regions
Part III; Functional defecation disorders
Chapter 4 Childhood constipation; an overview of genetic studies and associated 91 syndromes
Chapter 5 Symptoms of autism spectrum disorders in children with functional 119 defecation disorders
Chapter 6 Completion of toilet training in children with functional defecation 133 disorders and concomitant symptoms of autism spectrum disorders
Chapter 7 Personality, psychological distress, physical health and child rearing 147 practices of parents of children with functional constipation
Chapter 8 Sacral neuromodulation therapy: a promising treatment for adolescents 165 with refractory functional constipation
Summary and discussion 177
Nederlandse samenvatting 191
Contributing authors 199
List of publications 205
Dankwoord 209
Curriculum Vitae 217
General introduction and outline of the thesis
Parts of this introduction have been published as B. Peeters, R.C. Hennekam, Motility disorders and genetics: the future is bright. J Pediatr Gastroenterol Nutr 2011;53;Suppl 2:S1-3.
General introduction and outline of the thesis
General introduction Pediatric gastrointestinal motility disorders may present in the neonatal period (e.g. Hirschsprung disease or infantile hypertrophic pyloric stenosis), but may also become present later in childhood. The character, intensity and duration of symptoms may vary widely between patients with these disorders. It is known that gastrointestinal motility disorders can have a significant impact on the child’s life and the lives of his/her family.1-3 Despite the increasing possibilities in diagnostic techniques for gastrointestinal motility disorders, the pathophysiology of pediatric gastrointestinal motility disorders is still poorly understood. In this introduction, general information is provided about three gastrointestinal motility disorders commonly found in children; gastro-esophageal reflux disease, infantile hypertrophic pyloric stenosis, and functional defecation disorders. Furthermore, an introduction in to pathophysiological factors and associated behaviors in these pediatric gastrointestinal motility disorders is given.
Gastro-esophageal reflux disease The passive movement of gastric contents into the esophagus (gastro-esophageal reflux, GER) is a normal physiological mechanism occurring several times a day in every healthy infant, child and adult.4-6 However, when GER causes complaints and/or complications, the diagnosis of gastro-esophageal reflux disease (GERD) may be applicable.7,8 GERD is common in children, with an estimated prevalence of 12.3% in infants and 1% in childhood according to a database survey in the United States.9 Often, medical history in combination with physical examination of the child is sufficient to diagnose GERD. Helpful additional investigations are combined pH-intraluminal impedance monitoring and endoscopy.10 The first, important step in the treatment of pediatric GERD is parental guidance and education. Feeding thickeners, positioning advices and behavioral changes may relieve symptoms in a subset of patients.11,12 There is an on-going debate about drug prescription in treating GERD in infants and children. A recent systematic review by Van der Pol and colleagues concluded that the most commonly prescribed drugs - proton-pump-inhibitors (PPI’s) - are ineffective in reducing GERD-symptoms in infants and evidence is insufficient to support effectiveness and safety of PPI’s in children.13 There is a need for development of new therapeutic strategies for pediatric GERD, but this awaits further elucidation of the pathophysiological mechanisms behind symptoms of GERD in infants and children, such as genes causing or predisposing for GERD.
Infantile hypertrophic pyloric stenosis Infantile hypertrophic pyloric stenosis (IHPS) is a common gastrointestinal motility disorder of infancy in which an acquired narrowing of the pyloric muscle progressively leads to a nearly obstruction of the pyloric channel.14 Symptoms typically arise in a formerly healthy
11 General introduction and outline of the thesis infant between the third and sixth week after birth. Projectile postprandial vomiting is typically a key symptom of IHPS.15 Although the estimated incidence of IHPS is high among neonates (2/1.000 live births in the Western World), its etiology is still largely unknown.15,16 IHPS has a striking male predominance with a male-female ratio of 4-5:1.17 Frequently, a palpable mass in the upper abdomen is present and a peristaltic wave can be observed during feeding. Laboratory studies and ultrasound examination may help confirming the clinical diagnosis. Pyloromyotomy is the only definite treatment of IHPS. The (laparoscopic) pyloromyotomy is a relatively safe procedure, provided a metabolic alkalosis is corrected, and consists of an incision in the circular, hypertrophic pyloric muscle in line with the gut, as first described by Ramstedt in 1912.18,19 Conservative management, which consists of prolonged continuous nasoduodenal feeding, is rarely considered and only if a surgical approach seems unfeasible.
Functional defecation disorders Functional defecation disorders (FDD), functional constipation (FC) and functional non-retentive fecal incontinence (FNRFI), are common problems in children. The world-wide prevalence of functional constipation (FC) in children ranges from 0.7 to 29.6 %.20 Fecal impaction may lead to fecal incontinence which can be a source of considerable distress and embarrassment for the child and the family. In a subset of children, fecal incontinence occurs without signs of fecal retention, better known as ‘functional non-retentive fecal incontinence’ (FNRFI).21 FNRFI has a reported prevalence of 1.5 to 9.8% in children.22 Only in a small fraction of patients, a defecation disorder is secondary to a known pathology such as anorectal malformations, Hirschsprung disease, neurological abnormalities or a metabolic disorder.23 In the majority of patients however, the etiology remains unknown and a diagnosis of functional defecation disorder is made according to the internationally accepted ROME III criteria for pediatric functional gastrointestinal disorders.21 Psycho- education, strict toilet training and keeping bowel diaries combined with a rewarding system are key elements in the treatment of both FC and FNRFI. In addition, FC is generally treated with laxatives, enemas or colon lavage. In case of FNRFI, the use of Loperamide might be beneficial.24 Despite maximal appliance of current conservative treatment modalities, long term follow- up data show that symptoms of FC persist into adulthood in 25% of children, negatively affecting quality of life.25 A long-term follow-up study in children with FNRFI demonstrated that 70% of patients still had complaints after two years of intensive treatment. At the age of 12 years, almost 50% of FNRFI patients still suffered from fecal incontinence.26 These data demonstrate that there is a need for new treatment strategies for children with FDD. Better insight in the pathophysiology of FDD might be helpful in the development of new treatment modalities, as for now, little is known about the exact etiology of FDD.
12 General introduction and outline of the thesis
The pathophysiology of pediatric gastrointestinal motility disorders In the last decades, our knowledge about diagnostic techniques in gastrointestinal motility disorders has increased remarkably. However, the pathophysiology behind childhood motility disorders has remained largely hidden. Obtaining more insight in the pathophysiology of gastrointestinal motility disorders will be useful as it will lead to better understanding of these complex diseases and may potentially lead to enhanced therapeutic strategies. Genetic factors, environmental and behavioral factors are all likely to be involved in the complex pathophysiology of gastrointestinal motility disorders in children.
Genetic factors It is rapidly becoming clear that genetic factors play a role in common disorders such as diabetes mellitus, hypertension and most forms of cancer. It is likely that genetic factors play an important role in the etiology of gastrointestinal motility disorders as well. This becomes already evident when considering results of classical genetics studies: twin studies and familial aggregation studies have shown that several isolated (non-syndromic) motility disorders occur more frequently in relatives of affected persons compared to family members of healthy controls.27-31 Furthermore, childhood motility disorders are frequently part of the clinical spectrum of well-defined genetic syndromes.32 Various studies have been conducted in order to detect the molecular background of isolated motility disorders resulting in only a limited number of genes and their function. A major problem in the identification of these genes is beyond doubt the large genetic heterogeneity of gastrointestinal motility disorders: variations in many different genes can cause the same disease. Still, it will be extremely useful if genes causing gastrointestinal motility disorders and their functions will be detected. It will offer us insight in the complex pathophysiology of gastrointestinal motility disorders, and potentially will lead to new therapeutic strategies. The field of molecular genetic research is evolving rapidly, which is leading to new, promising and cost-effective techniques that will help identifying the genetic causes of not only Mendelian disorders but also of diseases with a complex origin. Below, we describe some of the available techniques that are likely to be instrumental in unravelling the genetic pathophysiology of gastrointestinal motility disorders in childhood.
Direct candidate gene sequencing One strategy starts by studying the function(s) of genes that are already known to cause a particular disorder. Almost without exception proteins (which are coded by genes) do not function in an isolated way but function together with a group of other proteins in a pathway. If one gene in such a pathway can cause a disorder, it may well be possible that mutations in other genes in the same pathway can cause the same disorder, or at least cause a disorder that resembles it. It is essential that the patients that are studied are
13 General introduction and outline of the thesis phenotyped in such a way they form groups as homogeneous as possible as this strongly increases the chance of finding causative genes. A well-known example of this is the MAPK pathway: first mutations in the gene PTPN11 were found to cause Noonan syndrome, and by candidate gene sequencing techniques a series of mutations were found in genes acting in the same pathway and causing either also Noonan syndrome or related entities such as Costello syndrome, CFC syndrome and LEOPARD syndrome.33 The increasing knowledge of gene functioning and gene interaction will presumably lead to more successful direct gene sequencing research in gastrointestinal motility disorders in the future.
Investigating syndromic motility disorders Another strategy to detect genes and pathophysiological pathways of isolated motility disorders is to study genes causing syndromic forms. One can recognize patients with the same disorder by the various, ‘non-motility’ manifestations of the syndrome and in this way gather groups of patients with the same cause of the motility disturbance. By studying the functions and associated pathways of genes involved in genetic syndromes with disturbed gut motility, more insight in complex pathophysiology can be obtained. As there are many different syndromic forms of motility disorders, the chance that a single gene or pathway will explain a large part of the group of patients with isolated motility disorder is small. The main yield of this strategy however is the valuable insight it provides in the various pathways leading to abnormal gastrointestinal motility.
Genome wide association studies In Genome Wide Association Studies (GWAS), numerous markers spread throughout the whole genome are used to identify common small variants called single nucleotide polymorphisms (SNPs) in large groups of non-related patients with a particular disorder. SNPs that occur more frequently within the studied population than in a group of healthy controls may indicate a genetic risk factor for the disorder under study. Examples of large GWAS’s are studies performed in groups of patients with hypertension, diabetes, psoriasis or psychiatric disorders. To our knowledge, GWAS studies in gastrointestinal motility disorders have only been performed in a group of patients with Hirschsprung disease and in a cohort of patients with IHPS.34,35 The genome wide association strategy is expensive as it requires large sample sizes to enable detection of significant differences between the affected and control population. Furthermore, most risk factors identified by GWAS’s account only for small proportions of the total genetic risk in complex diseases, due to marked genetic heterogeneity that characterizes many multifactorial disorders. Insufficiently large sample sizes and too low marker densities have been pointed out as factors causing problems in identifying genetic factors associated with complex diseases. 36 Lastly, GWAS only yields risk factors and not
14 General introduction and outline of the thesis causative genes: a risk factor may show an association with the disorder in an indirect way. Due to all these problems the number of GWAS’s is decreasing rapidly as more powerful, direct and cheap techniques have become available.
Linkage studies Linkage studies using markers spread over the whole genome and performed in large families with multiple affected members have a strong potential to identify loci at which disease causing genes are located .37 In linkage analysis, a prior hypothesis or a candidate region is not obliged as the segregation of genetic markers within a pedigree is studied by using microsatellites or single nucleotide polymorphisms (SNP’s) evenly distributed throughout the genome. Possibly associated chromosomal regions identified in this way need to be sequenced further by traditional Sanger sequencing or next generation sequencing (see Whole exome sequencing). Many genes for many entities have been found this way. For example, in 2006, a genome wide linkage analysis was performed in five affected and six non-affected members of one multigenerational family with isolated Hirschsprung disease.38 In this way, a novel susceptibility locus on chromosome 4q was identified for Hirschsprung disease. Up till now, at least ten genes and 5 loci have been found to be associated with isolated Hirschsprung disease, which underlines the clinical heterogeneity of this entity.39 It can be expected that linkage analysis in homogeneous isolated motility disorders in well-defined families will lead to the identification of disease associated genes. Subsequently, isolated genes can be checked in large series of unrelated patients to evaluate whether it is a common or rare explanation for the disturbed motility.
Whole exome sequencing Recently, a new genetic technique called whole exome sequencing (WES) using next generation sequencing techniques has become available. This technique focuses on just the exons, so the protein-coding parts of the genome, covering approximately 1% of the total genome. This decreases the work of sequencing dramatically, and especially the work attached to the bio-informatics thereafter. Sequencing all exons of the human genome (usually indicated as the exome), has proven to be robust, also for disorders with a presumably heterogenic background. In 2010, WES in just four affected individuals with a single, well defined entity was successful in identifying a disease associated gene. 40 From then, the genetic background of several complex disorders, such as the vast number of causes for autism spectrum disorders, has been further elucidated by WES each time using only small numbers of patients. 41,42 Which of the abovementioned techniques to apply in individual research projects largely depends on the degree of clinical homogeneity of the study population and to some extent
15 General introduction and outline of the thesis the available sample size. Detailed phenotyping of study populations remains a hallmark for successful genetic research.43
Environmental factors Next to the presence of certain variants within the genome (the genetic make-up of individuals), environmental factors, such as nutrition, climate, cultural habits and exposure to certain agents, might also play a role in the etiology of gastrointestinal motility disorders. Next to the direct influences on health that these factors may have, they may also influence our genome possibly leading to motility disorders. Our DNA is subject to continuous changes induced by such environmental factors that result in changes in imprinting status by shifts in methylation and thereby gene expression, which can be inherited over several generations.44 These factors may act anywhere between the moment of conception and postnatal life. It may be either completely environmentally determined factors, or environmentally determined factors that act mainly in the presence of a particular genetic constitution. Epigenetic changes should therefore also be considered when investigating the pathophysiology of pediatric gastrointestinal motility disorders.
Associated behaviors The association between behavioral factors and FDD has been increasingly acknowledged but the exact relationship between the two is still unclear. In more than one-third of children with an FDD, behavioral problems can be found.45-47 Up till now it has remained uncertain whether behavioral disturbances in general are primary or secondary to FDD. It can be hypothesized that pre-existing behavioral disturbances may lead to a complicated period of toilet training, which is known as a possibly critical phase in the development of FDD.53 On the other hand, the presence of an FDD might give rise to a considerable level of stress and embarrassment for the child and his/her family which may lead to adaptive behavioral changes. These behavioral changes might also become apparent in the parents of children with FDD. Little is known about the health status, personality and child rearing style of parents of children with FDD. Remarkably, in children with autism spectrum disorders, the prevalence of FDD has frequently been reported to be much higher than in the general population.48-52 However, no data is available about the prevalence of autism spectrum disorders in children presenting with FDD. Obtaining more insight in FDD associated behaviors in both children and parents might give rise to an adaptation of the current treatment strategies and might lead to a more systemic family-based approach when treating children with FDD.
16 General introduction and outline of the thesis
Outline of the thesis This thesis focuses on the further elucidation of the pathophysiology of the three most common gastrointestinal motility disorders in children; gastro-esophageal reflux disease, infantile hypertrophic pyloric stenosis and functional defecation disorders. Genetic factors, environmental factors and associated behaviors have been studied in order to increase our insight in these conditions.
Part I; Gastro-esophageal reflux disease (GERD) In Chapter 1 a large multigenerational Dutch family with multiple members affected with GERD is described. Detailed phenotyping of the family members was performed and subsequently genome-wide linkage analysis was conducted in order to identify genetic loci associated with GERD in this family.
Part II; Infantile hypertrophic pyloric stenosis (IHPS) An extensive overview of the current knowledge of the pathophysiology of IHPS is provided in Chapter 2. Genetic studies that have been performed in isolated forms of IHPS are discussed. Furthermore, a detailed overview of all non-isolated (syndromic) forms of IHPS is given. Pathophysiological pathways known to be associated with these extreme phenotypes are further categorized in order to obtain new insights in to the pathophysiology of isolated IHPS.
Studies that have been published regarding possible seasonal variations in the incidence of IHPS have been contradictory and local environmental factors have generally not been taken in to account. In Chapter 3, seasonal variations in the incidence of IHPS are investigated in two separate regions in the Netherlands correcting for local climate factors.
Part III; Functional defecation disorders (FDD) Chapter 4 comprises an overview of the current knowledge of genetic factors associated with childhood constipation. In this chapter, we discuss genetic studies conducted in isolated forms of childhood constipation. Subsequently, we provide an overview of clinical syndromes known to be associated with childhood constipation (syndromic forms). These non-isolated forms of childhood constipation are further subcategorized according to their presumed pathogenesis in order to provide better insight in to the possible pathophysiological pathways associated with isolated forms of childhood constipation.
In children with autism spectrum disorders, FDD have been commonly described. However, no data has been published about the prevalence of (symptoms of) autism spectrum disorders in children presenting with FDD. In Chapter 5, the prevalence of symptoms
17 General introduction and outline of the thesis of autism spectrum disorders is prospectively and systematically assessed in children presenting with an FDD at our specialized outpatient clinic.
The presence of a functional defecation disorder (FDD) may delay the moment of completion of toilet training. However, the association between the presence of symptoms of autism spectrum disorders and the moment of completion of toilet training in patients with FDD is unknown. In Chapter 6, we compare the moment of completion of toilet training between children with FDD and symptoms of autism spectrum disorders with children with an FDD only and controls from the general population.
In mothers of children with chronic abdominal pain, anxiety and depression have been found to be more commonly present compared to mothers of healthy children. No such data are available for the parents of children with FDD. More knowledge about this subject might improve our insight in the etiology of FDD in children and might learn us about the possible influences that the presence of an FDD in a child might have on parents. Health status, personality and child rearing style of fathers and mothers of children with FDD are described in Chapter 7.
We conclude with Chapter 8, where we describe the efficacy of a new therapeutic option in a subgroup of patients with a very specific constipation phenotype. In this chapter, the results of sacral neuromodulation therapy are demonstrated in a specific subgroup of female adolescent patients with severe refractory functional constipation.
18 General introduction and outline of the thesis
Reference List
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19 General introduction and outline of the thesis
20. Mugie SM, Benninga MA, Di LC. Epidemiology of constipation in children and adults: a systematic review. Best Pract Res Clin Gastroenterol. 2011;25:3-18. 21. Rasquin A, Di LC, Forbes D, Guiraldes E, Hyams JS, Staiano A, et al. Childhood functional gastrointestinal disorders: child/adolescent. Gastroenterology. 2006;130:1527-1537. 22. Burgers R, Benninga MA. Functional nonretentive fecal incontinence in children: a frustrating and long- lasting clinical entity. J Pediatr Gastroenterol Nutr. 2009;48 Suppl 2:S98-S100. 23. Kleinman, Goulet, Mieli-Vergani, Sanderson, Sherman, Schneider. Walker’s Pediatric gastrointestinal disease. 2008. 24. Voskuijl WP, van GR, Taminiau JA, Boeckxstaens GE, Benninga MA. Loperamide suppositories in an adolescent with childhood-onset functional non-retentive fecal soiling. J Pediatr Gastroenterol Nutr. 2003;37:198-200. 25. Bongers ME, van Wijk MP, Reitsma JB, Benninga MA. Long-term prognosis for childhood constipation: clinical outcomes in adulthood. Pediatrics. 2010;126:e156-e162. 26. Voskuijl WP, Reitsma JB, van GR, Buller HA, Taminiau JA, Benninga MA. Longitudinal follow-up of children with functional nonretentive fecal incontinence. Clin Gastroenterol Hepatol. 2006;4:67-72. 27. Chan AO, Hui WM, Lam KF, Leung G, Yuen MF, Lam SK, et al. Familial aggregation in constipated subjects in a tertiary referral center. Am J Gastroenterol. 2007;102:149-152. 28. Buonavolonta R, Coccorullo P, Turco R, Boccia G, Greco L, Staiano A. Familial aggregation in children affected by functional gastrointestinal disorders. J Pediatr Gastroenterol Nutr. 2010;50:500-505. 29. Krogh C, Fischer TK, Skotte L, Biggar RJ, Oyen N, Skytthe A, et al. Familial aggregation and heritability of pyloric stenosis. JAMA. 2010;303:2393-2399. 30. Trudgill NJ, Kapur KC, Riley SA. Familial clustering of reflux symptoms. Am J Gastroenterol. 1999;94:1172- 1178. 31. Cameron AJ, Lagergren J, Henriksson C, Nyren O, Locke GR, III, Pedersen NL. Gastroesophageal reflux disease in monozygotic and dizygotic twins. Gastroenterology. 2002;122:55-59. 32. Gockel HR, Schumacher J, Gockel I, Lang H, Haaf T, Nothen MM. Achalasia: will genetic studies provide insights? Hum Genet. 2010;128:353-364. 33. Aoki Y, Niihori T, Narumi Y, Kure S, Matsubara Y. The RAS/MAPK syndromes: novel roles of the RAS pathway in human genetic disorders. Hum Mutat. 2008;29:992-1006. 34. Garcia-Barcelo MM, Tang CS, Ngan ES, Lui VC, Chen Y, So MT, et al. Genome-wide association study identifies NRG1 as a susceptibility locus for Hirschsprung’s disease. Proc Natl Acad Sci U S A. 2009;106:2694- 2699. 35. Feenstra B, Geller F, Krogh C, Hollegaard MV, Gortz S, Boyd HA, et al. Common variants near MBNL1 and NKX2-5 are associated with infantile hypertrophic pyloric stenosis. Nat Genet. 2012;44:334-337. 36. Ropers HH. New perspectives for the elucidation of genetic disorders. Am J Hum Genet. 2007;81:199-207. 37. Dawn TM, Barrett JH. Genetic linkage studies. Lancet. 2005;366:1036-1044. 38. Brooks AS, Leegwater PA, Burzynski GM, Willems PJ, de GB, van L, I, et al. A novel susceptibility locus for Hirschsprung’s disease maps to 4q31.3-q32.3. J Med Genet. 2006;43:e35. 39. Amiel J, Sproat-Emison E, Garcia-Barcelo M, Lantieri F, Burzynski G, Borrego S, et al. Hirschsprung disease, associated syndromes and genetics: a review. J Med Genet. 2008;45:1-14. 40. Ng SB, Buckingham KJ, Lee C, Bigham AW, Tabor HK, Dent KM, et al. Exome sequencing identifies the cause of a mendelian disorder. Nat Genet. 2010;42:30-35. 41. O’Roak BJ, Deriziotis P, Lee C, Vives L, Schwartz JJ, Girirajan S, et al. Exome sequencing in sporadic autism spectrum disorders identifies severe de novo mutations. Nat Genet. 2011;43:585-589.
20 General introduction and outline of the thesis
42. Ku CS, Naidoo N, Pawitan Y. Revisiting Mendelian disorders through exome sequencing. Hum Genet. 2011;129:351-370. 43. Hennekam RC, Biesecker LG. Next-generation sequencing demands next-generation phenotyping. Hum Mutat. 2012;33:884-886. 44. Kaati G, Bygren LO, Edvinsson S. Cardiovascular and diabetes mortality determined by nutrition during parents’ and grandparents’ slow growth period. Eur J Hum Genet. 2002;10:682-688. 45. van Dijk M, Benninga MA, Grootenhuis MA, Last BF. Prevalence and associated clinical characteristics of behavior problems in constipated children. Pediatrics. 2010;125:e309-e317. 46. Benninga MA, Voskuijl WP, Akkerhuis GW, Taminiau JA, Buller HA. Colonic transit times and behaviour profiles in children with defecation disorders. Arch Dis Child. 2004;89:13-16. 47. Loening-Baucke V, Cruikshank B, Savage C. Defecation dynamics and behavior profiles in encopretic children. Pediatrics. 1987;80:672-679. 48. Afzal N, Murch S, Thirrupathy K, Berger L, Fagbemi A, Heuschkel R. Constipation with acquired megarectum in children with autism. Pediatrics. 2003;112:939-942. 49. Ibrahim SH, Voigt RG, Katusic SK, Weaver AL, Barbaresi WJ. Incidence of gastrointestinal symptoms in children with autism: a population-based study. Pediatrics. 2009;124:680-686. 50. Nikolov RN, Bearss KE, Lettinga J, Erickson C, Rodowski M, Aman MG, et al. Gastrointestinal symptoms in a sample of children with pervasive developmental disorders. J Autism Dev Disord. 2009;39:405-413. 51. Gorrindo P, Williams KC, Lee EB, Walker LS, McGrew SG, Levitt P. Gastrointestinal dysfunction in autism: parental report, clinical evaluation, and associated factors. Autism Res. 2012;5:101-108. 52. Wang LW, Tancredi DJ, Thomas DW. The prevalence of gastrointestinal problems in children across the United States with autism spectrum disorders from families with multiple affected members. J Dev Behav Pediatr. 2011;32:351-360. 53. Borowitz SM, Cox DJ, Tam A, Ritterband LM, Sutphen JL, Penberthy JK. Precipitants of constipation during early childhood. J Am Board Fam Pract. 2003;16:213-218.
21
Part I
Gastro-esophageal reflux disease
Chapter 1
Genome-wide linkage analysis in a multigenerational family identifies new susceptibility regions for gastro-esophageal reflux disease on chromosomes 4, 12 and 14
Babette Peeters, Marc A. Benninga, Wout O. Rohof, Mariel Alders, Gudrun Nürnberg, Peter Nürnberg, Raoul C.M. Hennekam chapter 1
Abstract Gastro-esophageal reflux disease (GERD) is the most common digestive disease in the Western world. The pathophysiology of GERD is multifactorial and genetic factors are likely to play a role in its etiology. Until now no genes have been confirmed to be associated with isolated GERD. In this study, we aimed to identify chromosomal regions associated with the GERD-phenotype in a large multigenerational Dutch family with multiple affected members by linkage analysis followed by whole exome sequencing. Twenty-eight members of the family were included in this study. Clinical information was obtained by the Reflux Disease Questionnaire (RDQ), a dedicated general questionnaire, and through 24 hour pH/impedance testing and upper endoscopies. Genome-wide linkage analysis according to an affected-only strategy yielded several suggestive loci at chromosomes 4, 12 and 14. However, subsequent exome sequencing of the linked regions did not allow the identification of variants in candidate genes likely to be associated with GERD in this family.
26 Chapter Molecular analysis in GERD 1 Introduction Gastro-esophageal reflux disease (GERD) is a condition in which the reflux of gastric contents into the esophagus causes troublesome symptoms and/or complications. (Vakil et al., 2006) GERD is the most common digestive disease in the Western world, with an estimated prevalence of 10-20%.(Dent et al., 2005) Typical symptoms of GERD are heartburn and regurgitation, and complications of GERD include erosive esophagitis, Barrett’s esophagus and eventually esophageal adenocarcinoma.(Vakil et al., 2006) However, the majority of patients have non-erosive reflux disease and experience typical GERD symptoms without visible esophageal injury.(Fass, 2007) The age of onset of GERD is variable. Many individuals develop the disease during childhood. Indeed, GERD is the most common esophageal disorder in children. On the basis of a large claim database that uses International Classification of Diseases, Ninth Revision (ICD-9), GERD was diagnosed in 12.3% of North American infants and in 1% of other pediatric age groups.(Nelson et al., 2009) The pathophysiology of GERD is multifactorial and includes dysfunction of the gastro- esophageal junction (GEJ), disturbed gastric and esophageal motility, abnormal composition of the refluxate and visceral hypersensitivity.(Rohof et al., 2009) Familial clustering and the high prevalence of GERD in twins indicate that genetic factors are likely to play a role as well in the complex pathophysiology of GERD.(Cameron et al., 2002;Lembo et al., 2007;Mohammed et al., 2003;Trudgill et al., 1999) Twin studies using large twin registry databases have reported an additive effect of genetic factors in GERD ranging from 13 to 43%.(Cameron et al., 2002;Lembo et al., 2007;Mohammed et al., 2003) Furthermore, there are multiple clinical syndromes of which causative mutations are known that are going along with GERD, also suggesting a genetic basis for GERD.(Post et al., 2005) The identification of associated genes is important as it could increase insight in the complex pathophysiology of GERD and may thereby even serve as a basis for the development of new treatment strategies for this common disease. In individuals with Barrett’s esophagus, frequently related to chronic GERD, two associated variants on chromosomes 6 and 16 were recently discovered by a genome wide association study.(Su et al., 2012) In families with isolated (non-syndromic) forms of GERD, few linkage studies have been performed aiming to identify genes associated with a GERD phenotype.(Asling et al., 2009;Hu et al., 2000b;Jirholt et al., 2011) However, up till now, replication studies have generally failed in confirming genes to be associated with GERD.(Hu et al., 2004;Jirholt et al., 2011;Orenstein et al., 2002) An explanation for the lack of robust results in earlier GERD studies might be clinical and genetic heterogeneity of GERD in the studied populations. Studying homogeneous populations, by means of performing whole exome sequencing in extreme phenotypes or performing linkage analysis followed by whole exome sequencing in large well-defined multigenerational affected families is likely to increase the chances to find associated genes.(Hennekam and Biesecker, 2012) Therefore, in this study, we perform
27 chapter 1 genome-wide linkage analysis in a single well-defined multigenerational family with multiple members affected by GERD in order to identify genetic loci associated with GERD.
Methods
Family Ascertainment and Clinical Evaluation All members of a four-generational Dutch Caucasian family known with GERD and without known consanguinity were asked to participate in this study. Informed consent was obliged for participation and was also obtained from the parents in children. This study was approved by the Medical Ethical Committee of the Academic Medical Center of Amsterdam. GERD was considered as a dichotomous trait in this study. Participants were considered to be affected with GERD if bothersome typical GERD symptoms (i.e. substernal burning and regurgitation) were present. Individuals with an evident history of GERD symptoms or status after anti-reflux surgery were considered to be affected, also if currently symptoms were absent. Participating family members filled out the Reflux Disease Questionnaire (RDQ) validated to determine the presence of GERD.(Shaw et al., 2001) The RDQ consists of three subscales; heartburn, regurgitation and dyspepsia. Subscales consist of several items on which response options are scaled as 6-point Likert-scores ranging from 0 to 5 for frequency (not present to daily present) and severity (not present to severely present). Subject’s scores can be calculated as a mean of item response with higher scores indicating a higher frequency or severity of symptoms. A specific GERD score can be calculated (the GERD dimension) by combining the heartburn and regurgitation subscales in to a median score. The RDQ has been shown to be a valid and reliable questionnaire with excellent construct validity for GERD. (Dent et al., 2010;Kulig et al., 2003;Nocon et al., 2005;Shaw, 2004) (Aanen et al., 2006) The RDQ-score has been used by multiple large clinical trials in GERD as inclusion criterion to define GERD.(Dent et al., 2008;Kahrilas et al., 2007) In addition, all participants filled out a questionnaire with specific questions about general health, timing of onset of symptoms, earlier diagnostic procedures such as 24 hour pH/impedance testing and upper endoscopy, and treatment (i.e. drugs; surgical). For participating children parents were asked to assist. Medical information concerning GERD was also retrieved from medical records and local physicians with written approval of participants. All affected adult members of the family were requested to donate 10cc of peripheral blood for DNA extraction. From affected children, buccal swabs were collected or blood drawing was combined with a scheduled venous puncture for regular patient care reasons. DNA was extracted from samples according to standard procedures.
28 Chapter Molecular analysis in GERD 1 SNP genotyping and linkage analysis As it could not be excluded that family members who were ‘unaffected’ at the time of study would develop GERD later on in life, we applied an ‘affected-only’ strategy. Genotyping was performed in certainly affected family members throughout all four generations using the Affymetrix GeneChip Human Mapping 250K Nsp Array. Relationship errors were evaluated with the help of the program Graphical Relationship Representation. (Abecasis et al., 2001) The program PedCheck was applied to detect Mendelian errors and data for SNPs with such errors were removed from the dataset.(O’Connell and Weeks, 1998) Non-Mendelian errors were identified with the program MERLIN and unlikely genotypes for related samples were deleted.(Abecasis et al., 2002) Parametric linkage analysis was performed with ALLEGRO, which was also used for haplotype reconstruction. (Gudbjartsson et al., 2000) Multipoint LOD scores were calculated. All data handling was performed with the graphical user interface ALOHOMORA.(Ruschendorf and Nurnberg, 2005)Gene Mapping Center, Max Delbruck Center (MDC Regions exhibiting LOD-scores of 1.5 or greater were further fine-mapped by usage of additional markers.
Whole exome sequencing For whole exome sequencing, 1ug of DNA was fragmented with sonifaction technology (Covaris, Woburn, MA, USA). The fragments were end-repaired and adaptor ligated, including incorporation of sample index barcodes. After size selection, the samples were subjected to an enrichment process with the SeqCap EZ Human Exome Library version 2.0 kit (Roche NimbleGen, Madison, WI, USA). The enriched pools were then sequenced on one lane of an Illumina HiSeq 2000 sequencing instrument (Illumina, San Diego, CA, USA) with a paired-end 2x100 bp protocol. We filtered primary data according to signal purity with the Illumina Realtime Analysis software version 1.8. Subsequently, we mapped the reads to the human genome reference build hg19 with the ELANDv2 alignment algorithm on a multimode compute cluster. By use of CASAVA version 1.8 (Illumina processing software, Illumina), PCR duplicates were filtered out and the output was converted into BAM format. Scripts developed in-house at the Cologne Center for Genomics (University of Cologne, Cologne, Germany) were applied to detect protein changes, splice sites, and overlaps with known variants. In particular, we filtered for high-quality rare (minor allele frequency <0.01) variants (dbSNP build 134, the 1000 Genomes database build 20110521, and the public Exome Variant Server, US National Heart, Lung, and Blood Institute Exome Sequencing Project, Seattle, WA, USA, build ESP5400). The resulting list of genes was then prioritised by taking into account scores obtained with Polyphen2 and Sorting Intolerant From Tolerant (SIFT) algorithms and genes with conspicuously high mutation rates. Furthermore, allele frequencies suiting a dominant inheritance model were filtered out. We analysed acceptor and donor splice-site mutations with a maximum entropy model and filtered for effect changes.
29 chapter 1
Power calculation An estimate of the probability of detecting linkage applying an affected-only strategy in this 4-generation family was performed using the computer program SIMLINK. Overall, the dominant model of inheritance had more power than the recessive model in the power estimation within this pedigree. When theta (recombination fraction between the disease causing gene and the typed marker) was considered zero under a dominant model of inheritance, the mean maximal LOD score was estimated to be 1.93 (SE 0.06) with a maximum of 6.47. Chances to find a suggestive LOD score (≥2.0) or possibly suggestive LOD-score (≥1.5) in this pedigree were estimated to be 46% and 56% respectively under dominant inheritance.
Results In total, twenty-eight members of the family participated in the study. The clinical characteristics of the participating family members are summarized in Table 1. Seventeen family members from four generations were affected with GERD as shown in the pedigree (Fig. I). The age of onset of symptoms showed a large variation ranging from infancy till 35 years. The disease status of I-2 remained uncertain. This family member had died at the
Figure I Pedigree of the family
? = unknown disease status; grey coloured = possibly affected; black coloured = affected; * = included in linkage analyses; † = included in exome sequencing age of 70 from esophageal cancer. It could not be determined with certainty whether this was related to GERD or not. Linkage analysis was performed using samples of seven family members from four generations (I-1; II-8; II-13; III-2; III-10; III-16; IV-1). In all the diagnosis was beyond doubt. As the status of I-2 remains uncertain, linkage analysis was also performed excluding all regions inherited from I-1.
30 Chapter
Molecular analysis in GERD
When including I-1 in the analyses, the parametric linkage curve showed four peaks of 1 which 3 were located in chromosome 4 and one in chromosome 14. After fine mapping, one of the peaks on chromosome 4 showed three separate linkage regions. Limiting SNPs of the linked regions can be found in Table 2. Subsequently conducted linkage analysis excluding all regions inherited from I-1 yielded only one region on chromosome 12 (Table 3). For each of the linked regions, the LOD-score was 1.8. The total numbers of genes in the regions were 163 and 18, respectively. After analyzing the variants found by exome sequencing in all the linked regions, there were no suggestive candidate genes left in the regions. Only one variant was considered as a candidate based on technical results, but this gene was excluded as a likely candidate based on gene function and was not confirmed by Sanger sequencing.
Discussion Although genetic factors are very likely to play a major role in the pathophysiology of GERD, up till now no causative genes have been reported. In this study, we described the clinical characteristics and results of linkage analysis and whole exome sequencing in a single multigenerational Dutch family with multiple members affected by GERD. GERD was seemingly transmitted as an autosomal dominant trait within the family (Fig. 1). We reasoned that it may be assumed that in such a family one or more genes are segregating and such segregating traits should become clear in linkage analysis. Clinical characteristics such as age of onset of symptoms and severity of symptoms varied to some extent between the family members but did not indicate heterogeneity. Linkage to regions on chromosomes 4, 12 and 14 was demonstrated. These linkage regions do not overlap with regions found in previous linkage studies in GERD patients (Table 4). In 2000, a linkage study in a single family with pediatric GERD showed linkage to #13q14.(Hu et al., 2000b) Subsequent studies did not succeed in identifying a GERD susceptibility gene in this region.(Hu et al., 2000a;Orenstein et al., 2002) In 2009, genome wide linkage analysis in 36 families (n=504 of which 237 were affected)) followed by an association study and protein analysis identified COL3A1 at #2q31, responsible for the synthesis of the protein collagen type 3, as a susceptibility locus for GERD and hiatal hernia.(Asling et al., 2009) Replication of this study by others has not been published. Recently, 4-aminobutyrate aminotransferase (ABAT, at #16p13.3), known to be involved in transient lower esophageal sphincter relaxations and reflux events in dogs, has been associated with GERD by linkage analysis in 36 families followed by an association study in trios.(Jirholt et al., 2011) The association could not be replicated by the same authors in an independent case-control cohort. We conducted whole exome sequencing of the linked regions in one of the affected family members used for linkage analysis. This yielded only one possibly associated variant which was excluded based on gene function and subsequent negative Sanger sequencing.
31 chapter 1
There are several possible explanations for the inability to identify an associated variant in the linked regions in the present family. First, the coverage of the presently sets of probes could have been insufficient which allowed escape of exon(s) with a causative variant associated with GERD. Second, causative variants may have been missed due to insufficient capture of exonic regions which has led to scoring these variants as unreliable. We have tried to overcome this by also taking into account variants in the linked regions with very low capture, but no additional candidate variants were detected this way. Third, the variant associated with GERD in this family may not be located in an exon but in an intron and affects the normal reading process of an exon this way. One may try to surmount this by performing whole genome studies of the areas with linkage. Alternatively, one may hypothesize that GERD is not mainly caused by a variant in a single gene but is polygenic in this family, so variants in different genes are associated with GERD in the various members of this pedigree. As GERD is common we cannot exclude that one or more of the family members used for the linkage analysis have a variant in a different gene as cause for the GERD compared to the others, which distorts the results of the linkage analysis. One may try to overcome this by using more affected family members in the linkage analysis and allowing various linkage studies, each time excluding parts of the pedigree. Lastly, the phenotyping within the family may contain one or more mistakes. The diagnosis of GERD can be based on additional studies such as upper endoscopy and 24-hour pH-impedance testing, but the sensitivity of such diagnostic tools is limited.(Dent et al., 2010) Furthermore, such invasive studies are not standard care for GERD patients, and results are usually not available in most patients. In the present family, GERD was confirmed by one of such tests or by anti-reflux surgery in 30% of individuals. In line with several large clinical trials we used RDQ scores to confirm the clinical suspicion for GERD. In the present family, affected individuals had significantly higher RDQ-scores compared to non-affected individuals (mean score 1.8±1.1 vs. 0±0, p<0.001). By using an affected-only strategy we avoided the problem of an apparently unaffected family member becoming affected at an older age. There was uncertainty of the status of the first generation whether I-2 might have been affected as well. We adapted the protocol for this by performing linkage in two ways, one with this person as affected and one as him being unaffected. In the future, it may be helpful to perform exome sequencing in more family members instead of only one individual. In this way, the chances to overlook important variants in exons due to capture problems might be further diminished. Secondly, the inclusion of more affected family members in separate linkage analyses throughout this family might allow for a polygenic background of GERD to come to light. Next to this, performing whole genome sequencing instead of whole exome sequencing might be feasible in order to be able to take intronic variants into account as well. Detailed phenotyping will remain a hallmark for success.
32 Chapter Molecular analysis in GERD 1 We conclude that the present study has led to the identification of new susceptibility regions for GERD. No definitive variant was found to be linked to GERD. Additional molecular studies are planned.
33 chapter 1
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34 Chapter
Molecular analysis in GERD
Nelson SP, Kothari S, Wu EQ, Beaulieu N, McHale JM, Dabbous OH (2009) Pediatric gastroesophageal reflux 1 disease and acid-related conditions: trends in incidence of diagnosis and acid suppression therapy. J Med Econ 12:348-355 Nocon M, Kulig M, Leodolter A, Malfertheiner P, Willich SN (2005) Validation of the Reflux Disease Questionnaire for a German population. Eur J Gastroenterol Hepatol 17:229-233 O’Connell JR, Weeks DE (1998) PedCheck: a program for identification of genotype incompatibilities in linkage analysis. Am J Hum Genet 63:259-266 Orenstein SR, Shalaby TM, Finch R, Pfuetzer RH, DeVandry S, Chensny LJ, Bannada MM, Whitcomb DC (2002) Autosomal dominant infantile gastroesophageal reflux disease: exclusion of a 13q14 locus in five well characterized families. Am J Gastroenterol 97:2725-2732 Post JC, Ze F, Ehrlich GD (2005) Genetics of pediatric gastroesophageal reflux. Curr Opin Allergy Clin Immunol 5:5-9 Rohof WO, Hirsch DP, Boeckxstaens GE (2009) Pathophysiology and management of gastroesophageal reflux disease. Minerva Gastroenterol Dietol 55:289-300 Ruschendorf F, Nurnberg P (2005) ALOHOMORA: a tool for linkage analysis using 10K SNP array data. Bioinformatics 21:2123-2125 Shaw M (2004) Diagnostic utility of reflux disease symptoms. Gut 53 Suppl 4:iv25-iv27 Shaw MJ, Talley NJ, Beebe TJ, Rockwood T, Carlsson R, Adlis S, Fendrick AM, Jones R, Dent J, Bytzer P (2001) Initial validation of a diagnostic questionnaire for gastroesophageal reflux disease. Am J Gastroenterol 96:52-57 Su, Gay LJ, Strange A, Palles C, Band G, Whiteman DC, Lescai F, Langford C, Nanji M, Edkins S, van der Winkel A, Levine D, Sasieni P, Bellenguez C, Howarth K, Freeman C, Trudgill N, Tucker AT, Pirinen M, Peppelenbosch MP, van der Laan LJ, Kuipers EJ, Drenth JP, Peters WH, Reynolds JV, Kelleher DP, McManus R, Grabsch H, Prenen H, Bisschops R, Krishnadath K, Siersema PD, van Baal JW, Middleton M, Petty R, Gillies R, Burch N, Bhandari P, Paterson S, Edwards C, Penman I, Vaidya K, Ang Y, Murray I, Patel P, Ye W, Mullins P, Wu AH, Bird NC, Dallal H, Shaheen NJ, Murray LJ, Koss K, Bernstein L, Romero Y, Hardie LJ, Zhang R, Winter H, Corley DA, Panter S, Risch HA, Reid BJ, Sargeant I, Gammon MD, Smart H, Dhar A, McMurtry H, Ali H, Liu G, Casson AG, Chow WH, Rutter M, Tawil A, Morris D, Nwokolo C, Isaacs P, Rodgers C, Ragunath K, Macdonald C, Haigh C, Monk D, Davies G, Wajed S, Johnston D, Gibbons M, Cullen S, Church N, Langley R, Griffin M, Alderson D, Deloukas P, Hunt SE, Gray E, Dronov S, Potter SC, Tashakkori-Ghanbaria A, Anderson M, Brooks C, Blackwell JM, Bramon E, Brown MA, Casas JP, Corvin A, Duncanson A, Markus HS, Mathew CG, Palmer CN, Plomin R, Rautanen A, Sawcer SJ, Trembath RC, Viswanathan AC, Wood N, Trynka G, Wijmenga C, Cazier JB, Atherfold P, Nicholson AM, Gellatly NL, Glancy D, Cooper SC, Cunningham D, Lind T, Hapeshi J, Ferry D, Rathbone B, Brown J, Love S, Attwood S, Macgregor S, Watson P, Sanders S, Ek W, Harrison RF, Moayyedi P, de CJ, Barr H, Stupka E, Vaughan TL, Peltonen L, Spencer CC, Tomlinson I, Donnelly P, Jankowski JA (2012) Common variants at the MHC locus and at chromosome 16q24.1 predispose to Barrett’s esophagus. Nat Genet 2012: Epub Ahead of Print Trudgill NJ, Kapur KC, Riley SA (1999) Familial clustering of reflux symptoms. Am J Gastroenterol 94:1172-1178 Vakil N, van Zanten SV, Kahrilas P, Dent J, Jones R (2006) The Montreal definition and classification of gastroesophageal reflux disease: a global evidence-based consensus. Am J Gastroenterol 101:1900-1920
35 chapter 1
Table 1 | Clinical characteristics of the participating family members ID sex age age onset regurgitation substernal RDQ GERD additional anti-reflux anti-reflux affected additional information symptoms burning dimension investigations surgery medication (yrs) score I-1 F 90 15 + + 2.3 - + (age 52 yrs) + + II-1 F 69 30 + + 0* hiatal hernia - + + II-3 M 67 - - - 0 - - - - II-5 M 65 18 + + 1.8 hiatal hernia - + + II-8 M 63 35 - since anti-reflux - since anti-reflux 0 Upper endoscopy: + (age 48 yrs) - + II- 8 and II-9 dizygote twins operation operation esophagitis 24 hour pH-testing abnormal II-9 M 63 30 + + 2.4 - - + + II-8 and II-9 dizygote twins II-10 M 62 - - - 0 - - - - II-11 M 59 15 + + 4 - - + + II-13 F 54 20 + + 3.1 Upper endoscopy: Grade - + + B esophagitis, hiatal hernia 24 hour pH/ impedance testing abnormal III-2 F 47 18 + + 1.6 - - + + III-4 F 24 19 + + 2.6 - - - + III-5 F 21 - - - 0 - - - - III-7 F 37 27 + + 1.7 - - - + III-9 M 29 28 + + 1.8 - - - + III-10 F 31 14 + + 3.4 - - + + III-13 M 36 4 + + 2.0 - - + + III-14 F 33 18 + + 0* - - - + III-16 F 27 0 + + 1.7 24 hour pH/ impedance - + + testing not conclusive III-17 M 25 0 + + 1.7 Upper endoscopy: - + + esophagitis 24 hour pH-testing abnormal IV-1 F 10 2 + + 1.0 - - - + IV-4 F 1 0 ? ? n/a - - - possibly acid smell, bed in Anti-Trendelenburg position, adapted feeding * No GERD-symptoms in the week prior to RDQ assessment, however chronic symptoms of heartburn and regurgitation during 39 (II-1) and 15 (III-14) years respectively.
36 Chapter
Molecular analysis in GERD
Table 1 | Clinical characteristics of the participating family members 1 ID sex age age onset regurgitation substernal RDQ GERD additional anti-reflux anti-reflux affected additional information symptoms burning dimension investigations surgery medication (yrs) score I-1 F 90 15 + + 2.3 - + (age 52 yrs) + + II-1 F 69 30 + + 0* hiatal hernia - + + II-3 M 67 - - - 0 - - - - II-5 M 65 18 + + 1.8 hiatal hernia - + + II-8 M 63 35 - since anti-reflux - since anti-reflux 0 Upper endoscopy: + (age 48 yrs) - + II- 8 and II-9 dizygote twins operation operation esophagitis 24 hour pH-testing abnormal II-9 M 63 30 + + 2.4 - - + + II-8 and II-9 dizygote twins II-10 M 62 - - - 0 - - - - II-11 M 59 15 + + 4 - - + + II-13 F 54 20 + + 3.1 Upper endoscopy: Grade - + + B esophagitis, hiatal hernia 24 hour pH/ impedance testing abnormal III-2 F 47 18 + + 1.6 - - + + III-4 F 24 19 + + 2.6 - - - + III-5 F 21 - - - 0 - - - - III-7 F 37 27 + + 1.7 - - - + III-9 M 29 28 + + 1.8 - - - + III-10 F 31 14 + + 3.4 - - + + III-13 M 36 4 + + 2.0 - - + + III-14 F 33 18 + + 0* - - - + III-16 F 27 0 + + 1.7 24 hour pH/ impedance - + + testing not conclusive III-17 M 25 0 + + 1.7 Upper endoscopy: - + + esophagitis 24 hour pH-testing abnormal IV-1 F 10 2 + + 1.0 - - - + IV-4 F 1 0 ? ? n/a - - - possibly acid smell, bed in Anti-Trendelenburg position, adapted feeding * No GERD-symptoms in the week prior to RDQ assessment, however chronic symptoms of heartburn and regurgitation during 39 (II-1) and 15 (III-14) years respectively.
37 chapter 1
Table 2 | Summary of the linked regions in the linkage analysis including I-1 Chromosome 4 4 4 4 4 14 SNP start rs13119207 rs10517069 rs17781708 rs919047 rs1699387 rs10141075 SNP end rs1450911 rs6554291 rs6849346 rs6532120 rs17050678 rs1882698 Region in cM 6.6 6.23 3.11 2.11 8.07 9.26 Cytogenetic location #4p13-p14 #4p13-q12 #4q12-q13 #4q13.3 #4q28.2-q31.1 #14q11.2 Genes in region TBC1D1 GRXCR1 SRD5A3 ANKRD17 PCDH10 POTEG PTTG2 KCTD8 TMEM165 ALB PABPC4L POTEM KLF3 YIPF7 CLOCK AFP TERF1P3 OR4N2 TLR10 GUF1 PDCL2 AFM PCDH18 OR4Q3 TLR1 GNPDA2 NMU RASSF6 SLC7A11 OR4H12P TLR6 GABRG1 EXOC1 IL8 CCRN4L OR4M1 FAM114A1 GABRA2 CEP135 CXCL6 ELF2 OR4K3 TMEM156 COX7B2 KIA A1211 PF4V1 OR4K2 KLHL5 RAC1P2 AASDH CXCL1 OR4K5 WDR19 GABRA4 PPAT PF4 OR4K1 RFC1 GABRB1 PAICS PPBP OR4K15 KLB COMMD8 SRP72 CXCL5 OR4K14 RPL9 ATP10D HOPX CXCL3 OR4K13 LIAS CORIN SPINK2 PPBPP2 OR4L1 UGDH NFXL1 REST CXCL2 OR4K17 C4orf34 NIPAL1 NOA1 MTHFD2L OR4N5 HIP2 CNGA1 POLR2B EPGN OR11G2 ZBTB12B TXK IGFBP7 EREG OR11H6 PDS5A TEC AREG OR11H4 N4BP2 SLAIN2 AREGB TTC5 LOC344967 SLC10A4 BTC CCNB1IP1 ARHH ZAR1 PARM1 PARP2 CHRNA9 FRYL TEP1 RBM47 OCIAD1 KLHL33 NSUN7 OCIAD2 OSGEP APBB2 CWH43 APEX1 NRCLP2 DCUN1D4 TMEM55B UCHL1 LRRC66 PNP LIMCH1 SGCB RNASE10 PMX2B SPATA18 RNASE9 TMEM33 USP46 RNASE11 DCAF4L1 DANCR OR6S1 C4orf1 ERVMER34-1 EDDM3A BEND4 RASL11B EDDM3B SHISA3 SCFD2 RNASE6 ATP8A1 FIP1L1 RNASE1 LNX1 RNASE3 CHIC2 RNASE2 GSX2 PDGFRA KIT KDR
38 Chapter
Molecular analysis in GERD
Table 3 | Results from linkage analysis excluding family member I-1 1 Chromosome 12 SNP start rs11175799 SNP end rs1629507 Region in cM 5.3 Cytogenetic location #12q14.3-q15 Genes in region HMGA2 LLPH TMBIM4 IRAK3 RBMS1P1 HELB GRIP1 CAND1 DYRK2 IFN6 IL26 IL22 MDM1 RAP1B NUP107 SLC35E3 MDM2 CPM
Table 4 | Results of previous linkage studies in patients with GERD Study Population Targeted on Significantly Replication results candidate region linked region (+ candidate gene) (Hu et al., 2000b) 1 family - #13q14 (HTR2A Not replicated in 5 families (Hu et al., 2000a))* (Orenstein et al., 2002) (Asling et al., 2009) 36 families - #2q31 (COL3A1) Replicated in the same study, other replication studies not performed (Jirholt et al., 2011) 36 families + #16p13.3 (ABAT) Not replicated in case-control cohort in the same study * HTR2A subsequently excluded by further fine mapping analysis (Hu et al., 2000a)
39
Part II
Infantile hypertrophic pyloric stenosis
Chapter 2
Infantile hypertrophic pyloric stenosis - genetics and syndromes
Babette Peeters, Marc A. Benninga and Raoul C. M. Hennekam
Nat Rev Gastroenterol Hepatol 2012 Nov;9(11):646-60, published online July 2012 chapter 2
Abstract Infantile hypertrophic pyloric stenosis (IHPS) is a common condition in neonates that is characterized by an acquired narrowing of the pylorus. The aetiology of isolated IHPS is still largely unknown. Classic genetic studies have demonstrated an increased risk in families of affected infants. Several genetic studies in groups of individuals with isolated IHPS have identified chromosomal regions linked to the condition; however, these could usually not be confirmed in subsequent cohorts, suggesting considerable genetic heterogeneity. IHPS is associated with many clinical syndromes that have known causative mutations. Patients with syndromes associated with IHPS can be considered as having an extreme phenotype of IHPS and studying these patients will be instrumental in finding causes of isolated IHPS. Possible pathways in syndromic IHPS include: (neuro)muscular disorders; connective tissue disorders; metabolic disorders; intracellular signaling pathway disturbances; intercellular communication disturbances; ciliopathies; DNA-repair disturbances; transcription regulation disorders; MAPK-pathway disturbances; lymphatic abnormalities; and environmental factors. Future research should focus on linkage analysis and next-generation molecular techniques in well-defined families with multiple affected members. Studies will have an increased chance of success if detailed phenotyping is applied and if knowledge about the various possible causative pathways is used in evaluating results.
44 Infantile hypertrophic pyloric stenosis-genetics and syndromes
Introduction Chapter Infantile hypertrophic pyloric stenosis (IHPS) is a common condition in neonates that is defined by acquired narrowing of the pylorus.1 Hypertrophy of the pyloric muscle progressively leads to almost complete obstruction of the gastric outlet, which causes symptoms when the neonate is 3–6 weeks old. The typical symptom is projectile 2 postprandial vomiting.2
IHPS can occur as an isolated entity or might be linked with chromosomal abnormalities, congenital malformations and clinical syndromes, which indicates that there is a genetic involvement. The exact aetiology of isolated IHPS is unknown. Various potential genetic loci have been identified, but no studies in large cohorts have confirmed these associations with isolated IHPS. By studying nonisolated, syndromic forms of IHPS, valuable clues can be obtained about the pathogenetic pathways involved in IHPS.
The aim of this Review is to gain further insight into the pathogenesis of isolated IHPS by establishing which pathways are involved in syndromes associated with IHPS. We provide an overview of molecular and genetic studies in patients with isolated IHPS and subsequently categorize the various syndromes associated with IHPS. We have also included definitions of the key terms used in these studies (Box 1).
Epidemiology of IHPS In western countries, the incidence of IHPS is two per 1,000 live births; IHPS is less common in other parts of the world.2, 3 A decline in the incidence of IHPS has been reported over the past two decades in northern European countries.4, 5 A comparable decline in the incidence of sudden infant death syndrome has been observed since parents were first encouraged to put babies in a supine sleeping position.4 As it has been suggested that IHPS is related to a prone sleeping position,4 this change is sleeping position could explain the drop in the incidence of IHPS. However, in other countries, this simultaneous decline in the incidence of IHPS and sudden infant death syndrome could not be demonstrated.6 The incidence of IHPS might vary seasonally, but results are contradictory (B. Peeters et al., unpublished work). IHPS affects males more often than females (male:female ratio of 4–5:1).7 A clear explanation for this striking skewed sex distribution is lacking, and the cause for this distribution can only be hypothesized. Genetic factors located at the X or Y chromosome might be considered; however, transmission patterns within families do not point to this solution.8-14 An influence of preferential X-chromosome inactivation patterns in females could be present that would inactivate a gene with an important influence in
45 chapter 2 the aetiology of IHPS. Epigenetic changes might also lead to gender-specific alterations in gene expression. Lastly, sex hormones could also be involved, although disorders that have a known change in the levels of sex hormones do not show an increased IHPS incidence, which argues against such an influence. A study published in 2011 investigated testosterone levels in umbilical-cord blood of 46 patients with IHPS and a matched control group and found no statistically significant differences.15 IHPS is considered as a complex disorder that results from genetic and environmental factors.7, 16 Maternal smoking and alcohol consumption during pregnancy might be environmental factors that contribute to IHPS.17-19 Prenatal and postnatal exposure to medication and hyperacidity in neonates have been the subject of research, without producing conclusive data.20, 21 The role of early exposure to erythromycin, a macrolide antibiotic, in the pathogenesis of IHPS deserves consideration. Erythromycin is an agonist of motilin that is known to induce contractions of the gastrointestinal tract. Since a rise in IHPS incidence was reported in infants prophylactically treated with erythromycin during a pertussis epidemic in 1999,22 others have reported comparable results in children exposed to this drug.23, 24 However, up until now, no notable alterations in the gene that encodes motilin have been found in patients with IHPS. Young maternal age (<20 yearrs) has also been indicated as a risk factor for IHPS, but results are inconsistent.25-27 Firstborn babies are more likely to develop IHPS than subsequent babies.7 Data on risks related to birth weight and feeding practices are still inconclusive.16 In premature infants, the onset of symptoms is delayed compared with infants born at term.26 This observation suggests the need for postnatal maturation before IHPS can develop.26 Local infections, for example, with Helicobacter pylori, have been considered as well; however, H. pylori gastritis is usually not demonstrable in gastric biopsy samples from patients with IHPS.28, 29 We conclude that numerous environmental factors are possibly associated with IHPS, but their true influence remains uncertain.
Isolated IHPS: family studies Genetic studies usually first study affected twins and familial IHPS.30-33 The male:female sex ratio in familial cases (3:1) is less skewed than in isolated cases (4–5:1).11, 13 In 1961, Carter proposed a multifactorial sex-modified threshold model of inheritance for IHPS in which females are protected by their sex.34 In a further study, Carter and Evans described an almost three times higher prevalence of IHPS in offspring of affected mothers compared with offspring of affected fathers.32 They hypothesized that affected mothers have a direct effect on their foetuses that contributes to the babies developing IHPS. Several other studies have also reported a higher prevalence of IHPS in offspring of affected mothers than in offspring of unaffected mothers.35, 36
46 Infantile hypertrophic pyloric stenosis-genetics and syndromes
Chapter A reanalysis of IHPS familial aggregation patterns showed that familial recurrence patterns were inconsistent with single major locus inheritance, but were compatible with multifactorial threshold inheritance as proposed by Carter or with effects of multiple interacting loci.37 No support was found for a maternal factor.37 Krogh et al.38 studied familial occurrence in first 2 degree, second degree and third-degree relatives of 3,362 affected children in a national Danish birth cohort. A 200-fold increase in prevalence was found among monozygotic twins and a 20-fold increase was found among siblings of affected children. Heritability was estimated to be as high as 87% by using a best fitting model of variance, taking in to account additive genetic factors and nonshared environmental components. No higher prevalence in maternal relatives compared with paternal relatives was found. An overview of aggregation studies in IHPS is provided (Table 1). The abovementioned studies indicate that genetic factors have an important role in the aetiology of IHPS and that IHPS is probably inherited as a multifactorial trait, aggregating in families under the influence of multiple environmental and genetic factors.
Isolated IHPS: molecular studies
Linkage analysis Linkage studies are summarized in Table 2; only the most salient findings are discussed below. Following the occurrence of IHPS in patients with a duplication of chromosome 9q, Chung et al.39, 40 performed linkage analysis of candidate region 9q11–q33 in 20 families with IHPS but did not find a major predisposing locus in this population. However, chromosome 9q can not be excluded as a possible factor in the aetiology of IHPS, as the small sample size was small; therefore, further studies in other populations will be needed. Vanderwinden et al.41 suggested that reduced expression of neuronal nitric oxide synthase (nNOS) in the pylorus of patients with IHPS contributed to the development of the condition. nNOS catalyzes nitric oxide (NO), which influences muscle relaxation in the gut (Figure 1), and it was hypothesized that a reduced concentration of NO leads to continuous constriction and eventually hypertrophy of the pylorus.42 Chung et al.9 demonstrated statistically significant linkage between IHPS and NOS1a on chromosome 12q in 13 of 27 families. These UK families had at least three affected family members. A Swedish study could not replicate the results in three families with multiple affected members.10 Three generations of a family that included 10 affected members were analyzed by a single nucleotide polymorphism (SNP)-based genome-wide scan and mapped to chromosome 16p12–p13 (LOD score 3.23). 10 additional families with at least six affected members were analyzed without yielding statistically significant LOD scores. Sequencing of major candidate genes in the region encoding proteins involved in smooth muscle relaxation
47 chapter 2
(for example, MYH11 and GRIN2A) did not show pathogenic mutations. Linkage to NOS1 was excluded.11 A genome-wide linkage scan of 81 pedigrees with 302 individuals (206 affected) showed susceptibility loci on chromosome 11q14–q22 (maximum LOD score 3.4) and Xq23 (maximum LOD score 4.8). Both chromosomal regions included candidate genes involved in the functioning of ion channels that are involved in smooth muscle control (that is, TRPC5 and TRPC6).13, 43 Yet, a study of 168 affected Chinese individuals failed to replicate the association between SNPs in the TRPC6 promoter and IHPS.44 Linkage to another susceptibility locus on chromosome 16q24 (maximum LOD score 3.7) could not be replicated in 14 other pedigrees, and sequencing of candidate gene SLC7A5, which is involved in the transport of factors that transduce NO activity, did not show pathogenic mutations.12 In 37 Swedish and 31 British families with IHPS, linkage to four regions (including the NOS1 region) was found.14 Sanger sequencing of two candidate genes, encoding glucagon-like peptide 2 and neuropeptide Y, did not yield positive results.14 We conclude that different loci have been identified by linkage analysis in families with multiple IHPS individuals; however, subsequent attempts to confirm these associations in other families were frequently unsuccessful, which suggests that IHPS is genetically heterogeneous.
Genome-wide association studies A genome-wide association study (GWAS) was performed in 1,001 Danish individuals with IHPS and 2,401 control individuals.45 Three SNPs, harbouring candidate genes MBNL1 and NKX2–5, could be replicated in a subsequent cohort of patients with IHPS and control individuals.45 MBNL1 is a regulator of splicing transitions in the first weeks of life and NKX2–5 encodes a homeobox transcription factor. Increased knowledge of pathogenetic pathways involved in IHPS is needed before further correlations and improved interpretation of GWAS results can be achieved.
Candidate gene and expression studies Kusafuka et al.43 studied the expression of NOS1 at the mRNA level in muscle biopsy samples from six patients with IHPS and three control individuals. A considerably lower expression was found in patients with IHPS than in control individuals, but study numbers were small.46 Saur et al.44 confirmed the altered NOS1 expression in pyloric tissue of patients with IHPS and showed that 3 of 16 investigated patients with IHPS had genetic alterations in a regulatory region of NOS1 exon 1c that influences the expression of NOS1, whereas 81 control individuals showed no abnormalities. Individuals carrying the affected allele had an appreciably increased risk of developing IHPS.47 The association could not be replicated in a Swedish population consisting of 54 patients with familial IHPS and 28 patients with sporadic IHPS,45 or in a Chinese population consisting of 56 patients with
48 Infantile hypertrophic pyloric stenosis-genetics and syndromes
IHPS and 86 control individuals.48, 49 Researchers from Germany sequenced the complete coding region of NOS1 in 43 patients with IHPS and 47 healthy control individuals without Chapter finding a statistically significant association with IHPS.50 In 2008, Svenningsson and co-workers51 sequenced the gene that encodes motilin (MLN) in 57 patients with IHPS and 184 control individuals. Motilin is a hormone known to be involved in generating 2 contractions in the gastrointestinal tract. No association between MLN and IHPS was demonstrated. Direct sequencing of RET, which is associated with motility disturbances in patients with Hirschsprung disease, did not yield statistically significant differences in variations between 32 patients with IHPS and 48 control individuals.52 In pyloric biopsy samples from infants with IHPS, the expression of desmin, which is involved in the organization and functioning of muscle fibres, was higher than in samples from control individuals.53 A comparably high expression of desmin was found in the pyloric tissue from two stillborn babies (gestational age 27 and 30 weeks), which suggests that in neonates with IHPS the organization of the pyloric muscle is in a foetal stage. Kobayashi et al.54 investigated whether innervation of smooth muscle cells was inappropriate in patients with IHPS. They found a lack of expression of neural cell adhesion molecule (NCAM) and NADPH-diaphorase within the pylorus of 18 affected individuals. Interstitial cells of Cajal, which have an important role in gastrointestinal motility, were found to be lacking in pyloric tissue of patients with IHPS.55, 56 We have summarized above only results of major published molecular investigations. Further studies that focus on, for example, hormonal factors, smooth muscle cell components, growth factors, extracellular matrix proteins, factors involved in muscle innervation and interstitial cells of Cajal have been published, without explaining the pathogenesis of isolated IHPS in more detail and are reviewed by Panteli et al.57
Animal studies In 1970, Dodge et al.58 succeeded in inducing IHPS in puppies after maternal stimulation with pentagastrin, a hormone that stimulates gastric acid secretion via the release of histamine. Subsequent studies investigating preoperative and postoperative levels of gastrin in children with IHPS have yielded contradictory results.59, 60 Vanderwinden’s41 NO hypothesis was confirmed in various mouse models that induced hypertrophy of the pyloric sphincter by targeted knockout of NOS1.61, 62 Other studies demonstrated pyloric hypertrophy in animals following perinatal inhibition of NO synthase.63-65 An Hph1 mouse mutant, originally developed as a model for phenylketonuria, was found to have an increased risk of developing IHPS.66 In humans, phenylketonuria is known to be associated with IHPS.67 Hph1 mice are deficient in tetrahydrobiopterin, which is a cofactor to the enzyme NOS. As a result, Hph1 mice show diminished NOS activity, which possibly leads to pyloric hypertrophy. The findings from these animal models indicate that NO synthase
49 chapter 2 is indeed essential for normal pyloric functioning. In 2008, it was reported that pyloric sphincter manometry in nNOS knockout mice yielded pressure levels and motility indices that were not statistically significantly different from wild-type controls.68 Still, nNOS deficiency in these mice led to clinical gastric stasis and bezoars. Animal models for many other human syndromes that are associated with IHPS have been reported,69, 70 but we have been unable to find descriptions of models with increased frequencies of IHPS.
Syndromic IHPS A large number of syndromes are associated with IHPS. The exact prevalence of syndromic forms of IHPS is unknown. However, in a retrospective study, the prevalence of at least one major congenital malformation in 4,000 patients with IHPS from New York State registries was increased compared with the general population (7% versus 3.7%).2 We performed a literature search to identify clinical syndromes that are associated with IHPS. Some of the thus retrieved syndromes are common, others rare, some are almost always associated with IHPS, in others the association has been reported only infrequently. We decided to tabulate all the syndromes here irrespective of frequencies, as data regarding the frequency of IHPS can be biased and incomplete. We subcategorized all syndromes according to their (presumed) pathogenesis (Tables 3–7). The functioning of the pyloric sphincter is complex and many hypotheses regarding the pathogenesis of IHPS exist (see below). We have categorized the syndromes in the pathogenetic subcategory that we assumed to have the most notable involvement. We discuss a single syndrome from each subcategory to illustrate the presumed pathogenesis of IHPS.
Neuromuscular X-linked myotubular myopathy 1, a recessive disorder, is characterized by abnormalities of skeletal muscles leading to severe hypotonia and respiratory distress (Table 3).71 In the majority of patients, X-linked myotubular myopathy 1 is caused by mutations in MTM1. This gene is located at Xq28 and encodes myotubularin, which is required for muscle cell differentiation. Mutations in MTM1 lead to an accumulation of central nuclei in skeletal muscle. A zebrafish model of X-linked myotubular myopathy 1 showed abnormal neuromuscular junction organization, which suggests that impaired neuromuscular transmission is present.72 Herman et al.71 described a history of IHPS in 4 of 35 patients with X-linked myotubular myopathy 1. The pathogenesis of IHPS in these patients remains unknown. The abnormal differentiation of muscle cells might lead to localized morphological muscle changes. Impaired neuromuscular transmission, as observed in zebrafish, could also result in abnormal pyloric innervation, leading to obstruction of the pylorus.
50 Infantile hypertrophic pyloric stenosis-genetics and syndromes
Connective tissue Chapter Patients with Ehlers–Danlos syndrome (EDS) type III present with joint hypermobility and might have aortic or mitral regurgitation (Table 3).73 EDS type III can be caused by mutations in TNXB, which encodes the extracellular matrix protein tenascin XB.74 In one patient with the clinical characteristics of EDS type III, a mutation in COL3A1 (which 2 encodes procollagen III) has been reported; this mutation typically causes EDS type IV with severe skin problems and vascular ruptures.75 De Felice et al.76 described noteworthy asymptomatic joint hypermobility in children with IHPS and their parents. The patients with joint hypermobility showed an increased frequency of absent mandibular frenulum, suggesting a systemic abnormality of the extracellular matrix. Other studies have found high amounts of newly synthesized procollagen in the pylorus of patients with IHPS, suggesting that the pylorus is actively synthesizing collagen, which results in hypertrophy.77
Metabolic Smith–Lemli–Opitz syndrome (SLOS) is a multiple congenital malformation syndrome caused by mutations in DHCR7 that result in a deficiency of 7-dehydrocholesterol reductase (Table 4 ).78 This enzyme is the last in the cholesterol biosynthesis cascade and a deficiency leads to the accumulation of cholesterol precursors and consequently reduced concentrations of cholesterol.79 Symptoms include intellectual disability, failure to thrive, behavioural abnormalities, unusual face morphology, gastrointestinal disorders and skeletal,
Figure 1 | Nitric oxide and its influence in smooth muscle relaxation. Simplified scheme of the metabolic pathway of nitric oxide and its role in smooth muscle cell relaxation in the gastrointestinal tract. Abbreviations: cGMP, cyclic guanosine monophosphate; GTP, guanosine triphosphate; NO, nitric oxide; NOS, nitric oxide synthase.
51 chapter 2 genital and organ malformations.78 Schechter et al.26 calculated the incidence of SLOS in infants with IHPS to be 157-fold higher than in control individuals. IHPS was reported in 14% of 164 patients with histochemically confirmed SLOS.78 A study investigating plasma levels of sterol in 10 patients with isolated IHPS and full analysis of the cholesterol pathway in fibroblasts in three of the patients showed no detectable cholesterol abnormalities.80 How IHPS develops in patients with SLOS remains unknown.
Intracellular signalling pathway disturbances Familial nodular heterotopia is characterized by periventricular heterotopic nodules and seizures. The condition has been linked to mutations in FLNA, which is located on chromosome Xq28. FLNA encodes filamin A, a protein that regulates the reorganization of the actin cytoskeleton by interaction with integrins, transmembrane receptor complexes and second messengers. Filamin A is important for modulation of cell migration, therefore mutations in FLNA might lead to neuronal and non-neuronal migration defects. Mutations in FLNA might also result in chronic idiopathic intestinal pseudo-obstruction (OMIM# 300048) and FG syndrome 2 (OMIM# 300321), both of which are associated with IHPS. How disturbed intracellular signalling might lead to IHPS is unknown. Nezelof81 reported X-linked periventricular nodular heterotopia associated with a short gut, intestinal malrotation and IHPS in three patients. The myenteric plexus of these patients was normal, which suggests that a neuronal migration or neuromuscular transmission defect might be responsible for the clinical symptoms of X-linked periventricular nodular heterotopia.
Intercellular communication disturbances Hypoplastic left heart syndrome is characterized by an underdevelopment of the left ventricle and its components, which results in a disturbed circulation with patent ductus arteriosus and foramen ovale and enlargement of the right atrium, right ventricle and pulmonary artery (Table 4).82 GJA1, localized at 6q21, has been associated with hypoplastic left heart syndrome.83 GJA1 encodes gap junction α1 protein, a major component of gap junctions containing intracellular channels, which are important for diffusion of ions and signalling molecules from cell to cell. Gap junctions are thought to have an important role in the synchronized heart contraction and in embryonic development. IHPS has been described in a case report of a patient with hypoplastic left heart syndrome.84 GJA1 has also been associated with oculodentodigital dysplasia (OMIM# 164200). Patients with oculodentodigital dysplasia often present with a spastic bladder.85 Therefore, one could speculate that a gap junction disorder can lead to overstimulation of the bladder in patients with oculodentodigital dysplasia and of the pylorus in patients with hypoplastic left heart syndrome.
52 Infantile hypertrophic pyloric stenosis-genetics and syndromes
Ciliopathies Chapter Kallmann syndrome is characterized by hypogonadotropic hypogonadism and anosmia (Tables 3 and 5). Other features include delayed skeletal maturation, cleft lip and/or palate, renal agenesis and manual synkinesis. Six genes have been identified that are associated with Kallmann syndrome (Tables 3 and 5) but in nearly 70% of cases the genetic defect 2 remains to be discovered.86 Deletions in KAL1 have been found in about 7% of patients with Kallmann syndrome. KAL1 encodes a protein—anosmin-1—that has notable similarities with proteins involved in neural cell adhesion and axonal path finding, as well as the movement of cellular components.87 This finding suggests that KAL1 could have a specific role in neuronal migration and has functional characteristics resembling those of cilia. Cilia are omnipresent organelles that function as antennae of the developing cell.88 How this property relates to IHPS is uncertain.89
DNA-repair disturbances Cornelia de Lange syndrome is characterized by growth retardation, intellectual disability, characteristic facial features, limb defects, hirsutism, gastrointestinal dysfunction and cardiac, ophthalmologic and genitourinary abnormalities (Table 5).90 Jackson et al.91 reported that 12 of 310 patients with Cornelia de Lange syndrome had a history of IHPS. Cornelia de Lange syndrome is associated with mutations in NIPBL, located at 5p13–14, in up to 56% of patients. The fly homologue of NIPBL, Nipped-B, facilitates enhancer– promoter communication and regulates Notch signalling and other developmental pathways.92 Nipped-B is also homologous to a family of chromosomal adherins with roles in chromatid cohesion, chromosome condensation and DNA repair. In human cells with mutant NIPBL, the binding of cohesin to promoter regions of actively expressed genes is reduced, suggesting another role of NIPBL in transcriptional dysregulation.93 Cornelia de Lange syndrome is regarded as a cohesinopathy, but it remains uncertain whether the disturbed chromatid cohesion or transcription regulation causes the increased incidence of IHPS in patients with this syndrome.
Transcription regulation disorders Renal cysts and diabetes syndrome is characterized by renal cysts, maturity-onset diabetes of the young, genital tract malformations and gout (Table 5).94 Mutations in HNF1B, which encodes transcription factor HNF-1β, can cause the phenotype. HNF-1β is also expressed in the human gut.95 In 1989, the cases of a mother and son with hypoplastic glomerulocystic kidney disease were described. The mother had a history of IHPS and the son did not.96 In 2001, Bingham et al.95 described that both patients had developed early onset diabetes. IHPS has been found in several other diseases associated with renal cysts (Tables 4 and 5). No clear explanation for this association is available. However, in rats with polycystic
53 chapter 2 kidney disease, down-regulation of NO was involved in cyst formation97 and NO has been identified as a presumably important factor in the pathogenesis of IHPS.41
MAPK-pathway disturbances Costello syndrome is a systemic disorder characterized by increased prenatal growth, postnatal growth retardation, coarse face, loose skin, nonprogressive cardiomyopathy, a predisposition for malignancies, developmental delay and an outgoing friendly behaviour (Table 5).98 Over 80% of patients share the same HRAS mutation that affects the MAPK pathway.99 Gripp et al.100 reported IHPS in 5 of 58 patients with Costello syndrome who had an HRAS mutation and speculated that IHPS might result from a localized muscular hypertrophy similar to the hypertrophic cardiomyopathy that is frequently part of Costello syndrome. IHPS has also been described in some other disorders caused by mutations in the MAPK pathway (Table 5). In neurofibromatosis type 1, an adult case with pyloric obstruction by a neurofibroma has been reported, but obviously this was not a patient with IHPS.100 This case might suggest that neonates with neurofibromatosis type 1 can present with symptoms similar to those seen in classical IHPS that are caused by a neurofibroma obstructing the pylorus.
Lymphatic abnormalities Lymphoedema-lymphangiectasia-intellectual disability syndrome (LLIDS) is characterized by congenital lymph vessel dysplasia manifesting as congenital lymphoedema of the limbs and intestinal lymphangiectasia, accompanied by unusual facial morphology, variable intellectual disabilities and infrequently other malformations (Table 6).101 Mutations in CCBE1 have been found in 23% of patients, suggesting genetic heterogeneity.102 Hogan et al.103 suggested that CCBE1 defines an independent regulator of lymphangioblast budding and possibly migration. IHPS has been described in one patient with LLIDS, but also in other syndromic forms of lymphatic abnormalities.104-106 The exact mechanism behind the co-occurrence of lymphatic abnormalities and IHPS is unknown.
Environmental Of all the teratogenic agents, alcohol is probably the most common in the general population. Foetal alcohol syndrome results from ethanol exposure during pregnancy and consists of a broad spectrum of developmental defects (foetal alcohol spectrum disorders). Growth retardation, malformations, certain facial features and impairment of the central nervous system are the most common manifestations (Table 6). Neuronal and glial cells seem to be especially vulnerable to ethanol exposure. IHPS has been described in several patients with foetal alcohol syndrome.18, 19, 107 No clear explanation for this association exists.
54 Infantile hypertrophic pyloric stenosis-genetics and syndromes
Chromosomal Chapter IHPS is present as a clinical feature in several chromosomal abnormalities (Table 7). This finding suggests that IHPS might be part of contiguous genetic syndromes that involve genes necessary for normal pyloric functioning.108 Except for duplication 9q syndrome, no regions of these chromosomal anomalies have been studied in more detail to identify 2 genes associated with IHPS. Nowadays, array-comparative genomic hybridization (array-CGH) has become the first test to perform in patients with congenital malformations or other syndromes.109 With array-CGH, imbalances in groups of genes and sometimes even in individual genes can be identified. Therefore, such arrays might yield valuable results in patients with IHPS, especially those with nonisolated forms. As array-CGH has been applied for a limited number of years in a limited number of countries at the present time, interesting results might be expected in the near future.
Unknown The pathogenesis of many syndromes that are associated with IHPS is unknown (Table 6). As our knowledge of gene defects and gene functioning increases, our understanding of the pathophysiology of IHPS will probably improve rapidly in the near future.
Conclusions We have demonstrated that extensive research in isolated IHPS has shown that genetic factors have an important role in the pathophysiology of IHPS, but despite this observation no causative gene or genes have been recognized. Linkage studies have provided heterogeneous results and could not be replicated in subsequent studies. In the first GWAS, only a very small proportion of IHPS cases could be explained by the identified loci.110 The explanations for this lack of robust results remain uncertain. One explanation might be clinical and genetic heterogeneity of IHPS. Our observation that nonisolated IHPS can be caused by mutations in genes with very different functions provides additional evidence that isolated IHPS will probably be similarly heterogeneous. Indeed, genetic heterogeneity in disorders is much more frequent than anticipated, as has been shown in schizophrenia and intellectual disability.111, 112 If a similarly large genetic heterogeneity does exist in IHPS, it would hamper GWAS considerably. A second explanation might be differences between study populations. These differences might be in genetic make-up, that is, the presence of differences in several variants within the genome, but it might also be caused by differences in environmental factors, such as nutrition and cultural habits. Our DNA is subject to continuous changes induced by such environmental factors that result in changes in imprinting status and thereby gene expression, which can be inherited over several generations.113 This pattern will not become apparent when performing
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GWAS. Therefore, the role of epigenetic factors should also be considered when studying IHPS in different populations. Nowadays, the strategy to detect causes of heterogeneous disorders is often the use of next-generation technologies in extreme phenotypes and/or GWAS in large cohorts of patients. Causative genes of many of the syndromes in Tables 3–7 have been found by positional cloning techniques, but in recent years next-generation techniques have proved to be increasingly successful. Still, positional cloning studies in families with multiple affected members are valuable and have a considerable chance for success. Interpretation of results of GWAS has been more difficult as a result of the heterogeneity of many disorders.114 Interpretation will probably become more successful if the various ways a disorder can be caused are known. Knowledge of pathogenetic pathways and networks will enable more targeted evaluation of data and recognition of correlations in evaluating results of GWAS. This Review outlines our present knowledge of causes of both isolated and syndromic IHPS, and is a first attempt to group causes of syndromic IHPS on the basis of presumed pathogenesis. A reliable clue for the pathogenesis of IHPS could be found in only a limited number of syndromes. Categorizing the disorders generates the general hypotheses regarding the pathogenesis of isolated IHPS (Box 2). Undoubtedly the tabulation will contain mistakes, as with time more and possibly other functions of genes will become clear. Furthermore, in more syndromic conditions a correlation between the syndrome and IHPS will become evident, which might open new avenues of investigation. IHPS is a very heterogenic disorder. Research in the near future should therefore focus on extreme phenotypes that are present in syndromic forms of IHPS, and on well-defined large multigenerational families with multiple affected members or GWAS. Studies will have the best chance for success if detailed phenotyping is applied and if knowledge about the various possible causative pathways is used.115 We hope this Review will serve as a basis for future studies in IHPS, and will stimulate researchers to use the results of extreme phenotype studies in evaluation of their results in isolated IHPS.
Review Criteria The PubMed, Embase and Online Mendelian Inheritance in Man (OMIM) databases and London Medical Databases (LMDB) were searched using the term ‘pyloric stenosis’ combined with ‘epidemiology’, ‘family’, ‘aggregation’, ‘clustering’, ‘linkage (genetics)’, ‘genome wide association study’, ‘genetic association studies’, ‘genes’, ‘syndrome’, ‘disease’, ‘disorder’, ‘genetic’. IHPS was defined as an acquired hypertrophy of the pylorus in a baby with a maximum age of 12 months. Patients born with an obstruction of the pylorus or prenatally diagnosed IHPS were excluded. No language restrictions were applied. Reference lists of retrieved papers were hand searched for other relevant papers.
56 Infantile hypertrophic pyloric stenosis-genetics and syndromes
Box 1 Definitions of genetic terms Chapter Epigenetics is the study of heritable changes in DNA expression by changes other than mutations in the DNA sequence itself. The best known examples are alterations in DNA methylation or histone modification, which both lead to a change in reading the DNA sequence and therefore in production of the proteins coded for by that part of the DNA. 2 Familial aggregation describes clustering of a disorder within a family beyond what might be expected by chance. Such clustering is usually caused by genetic factors or shared environmental factors. Heritability is the proportion of differences in a particular sign or symptom within individuals that is attributable to genetic differences. Linkage analysis is the method to determine whether a disorder is inherited within a family together with certain parts (loci) of the DNA, which would point to localization of the cause of the disorder in these cosegregating parts. The analyses use markers spread more or less evenly throughout the genome. SNP are a variation in the sequence of the DNA that can exist between persons. Usually SNPs have two different forms but some have more. SNPs are most often found in noncoding regions of the DNA and are less common within genes. Whole-exome sequencing is the selective sequencing of the total genome of only the coding regions of genes (exons) and not the non-coding DNA within genes (introns) or between genes. Next-generation sequencing is a high throughput method of sequencing making it possible to sequence the complete genome or large regions of the genome in a short period of time for acceptable costs. Genome-wide association studies examine genetic variants (SNPs) in individuals of a population to identify an association between a disorder and such variants. This way one hopes to identify genes that cause the disorder. Genome-wide array comparative genomic hybridization is a high-resolution analysis of copy number variations in the whole genome. This method enables very small structural changes of chromosomes (deletions or duplications) to be detected. Extreme phenotype is the occurrence of a sign or symptom in a person with a disorder in such a way that it clearly sets this person apart from others with this disorder. This sign or symptom can be directly related to the disorder but also completely unrelated. It enables recognition of specific subgroups in individuals with a disorder, which has proven to be extremely helpful in finding causes of disorders.
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Box 2 Identified pathogenetic pathways that can be associated with IHPS Neuromuscular disorders Changes in differentiation or innervation of the pylorus, either innate or acquired, might lead to hypertrophy of the pylorus. This results in an obstruction causing IHPS. Connective tissue disorder Abnormal or excess of connective tissue in the pylorus gradually developing after birth leads to a mechanic obstruction of the pylorus or to altered muscular functioning resulting in prolonged contractions of the pylorus. Metabolic disorder We assume disturbed intracellular metabolism in the pylorus or a storage phenomenon might both be possible. Intracellular pathway disturbance Unknown mechanism. Intercellular communication disturbance One may postulate that disturbed signalling between cells causes abnormal stimulation of pyloric muscle cells. Ciliary malfunctioning Unknown mechanism. DNA-repair disturbance Unknown mechanism. Transcription regulation disorder Unknown mechanism. MAPK-pathway disturbances Unknown mechanism; it has been suggested that hypertrophy of the pyloric muscle has the same pathogenesis as the hypertrophic cardiomyopathy that can be a manifestation of a disturbance of this pathway. Lymphatic abnormalities Unknown mechanism. Environmental factors Unknown mechanism.
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Table 1 | Overview of familial aggregation studies investigating the risk for IHPS* Study Population M:F ratio Incidence population Heritability Family member affected with IHPS is (overall, male, female) Father Mother Father or Brother Sister Brother or Monozygotic Dizygotic twin mother sister twin sibling sibling Krogh et al. 1,999,738 Danish 4.4:1 1.7/1.000 87% NR NR NR 16.7, 17.5, 29.8, 28.2, 18.5, 18.8, overall 182 overall 29.4 (2010)38 children of whom 3362 M 2.7 13.8 37.1 17.9 had IHPS F 0.7 Czeizel & Tusnady 148 Hungarian cases 4-5:1 1.5/1.000 NR NR NR 9.3, NR, NR 31, 19, 75 80, 91, NR 42, 36.1, 59.5 NR NR (1984)‡ 116 M 2.2 F 0.7 Adelstein & Fedrick 220 UK cases 5.5:1 2.5/1.000 NR NR NR NR 32, 33.6, 24 NR 28.4, 29.1, NR NR (1976)‡ 117 M 4.1 20.8 F 0.8 Dodge 480 Irish cases 4:1 2.6/1.000 1st degree 58%; 2nd degree NR NR NR 25.3, 22.3, 31.3, 29.8, 26.8, 24, 32.4 overall 154 NR (1970)‡§ 118 M 4.2 24%; 3rd degree 38% 30.4 37.7 F 1.0 Carter & Evans 563 UK cases 5:1 3/1.000 1st degree 76%; 2nd degree 13.2, 11, 43.7, 37.8, 20.2, 17.2, 8, 5.3, 27.4, 20, 15.3, 11.1, NR NR (1969a)‡32 M 5.0 27%; 3rd degree 50% 24 70 34.3 21.5 63.3 18.6 F 1.0 Carter & Evans 426 UK cases 5:1 3/1.000 1st degree 76%; 2nd degree NR NR NR 13.5, 9.9, 12.8, 15.5, 13.3, 11.4, NR NR (1969b)‡32 M 5.0 27%; 3rd degree 50% 31.6 NR 23 F 1.0 McKeown et al. 489 UK cases 4.2:1 3/1.000 NR NR NR NR 18.5, 19.4, 8.8, 9.5, 16.9, 17.4, NR NR (1951)‡ 119 M 4.7 19.3 NR 16.6 F 1.1 *Risks are displayed as sex specific rate ratios (incidence in relatives/incidence in reference population according to sex). ‡Included in the re-analysis by Mitchell et al.37 §Male and female incidence rates were estimated by the authors of this actual paper based on the given overall incidence rate and sex ratio. Risk ratios were calculated based on data provided by Mitchell et al.37 Abbreviations: IHPS, infantile hypertrophic pyloric stenosis; F, female; M, male.
Table 2 | Overview of linkage studies in infantile hypertrophic pyloric stenosis Study Population Targeted on Significant Chromosomal Replication candidate linkage region region (candidate gene(s)) Chung 20 families Yes No 9q11- q33 No (1993)8 (dupl 9q syndrome) Chung 27 families Yes Yes 12q (NOS1) Unsuccessful (1996)9 (Söderhall 1998) Söderhall 3 families Yes No 12q (NOS1) No (1998)10 Capon (2006)11 1 family No Yes 16p12–13 Unsuccessful in 10 (MYH11, GRIN2A) additional families (Capon 2006) Everett (2008)13 81 families No Yes 11q14–q22, Xq23 No (TRPC5, TRPC6) Everett 1 family No Yes 16q24 (SLC7A5) Unsuccessful in 14 (2008)120 additional families (Everett 2008) Svenningsson 37 families and 31 No Yes 2q24 (GLP-2), 6p21 No (2012) 14 additional families (MLN), 7p21 (NPY), 12q24 (NOS1)
60 Infantile hypertrophic pyloric stenosis-genetics and syndromes
Table 1 | Overview of familial aggregation studies investigating the risk for IHPS* Chapter Study Population M:F ratio Incidence population Heritability Family member affected with IHPS is (overall, male, female) Father Mother Father or Brother Sister Brother or Monozygotic Dizygotic twin mother sister twin sibling sibling Krogh et al. 1,999,738 Danish 4.4:1 1.7/1.000 87% NR NR NR 16.7, 17.5, 29.8, 28.2, 18.5, 18.8, overall 182 overall 29.4 (2010)38 children of whom 3362 M 2.7 13.8 37.1 17.9 had IHPS F 0.7 2 Czeizel & Tusnady 148 Hungarian cases 4-5:1 1.5/1.000 NR NR NR 9.3, NR, NR 31, 19, 75 80, 91, NR 42, 36.1, 59.5 NR NR (1984)‡ 116 M 2.2 F 0.7 Adelstein & Fedrick 220 UK cases 5.5:1 2.5/1.000 NR NR NR NR 32, 33.6, 24 NR 28.4, 29.1, NR NR (1976)‡ 117 M 4.1 20.8 F 0.8 Dodge 480 Irish cases 4:1 2.6/1.000 1st degree 58%; 2nd degree NR NR NR 25.3, 22.3, 31.3, 29.8, 26.8, 24, 32.4 overall 154 NR (1970)‡§ 118 M 4.2 24%; 3rd degree 38% 30.4 37.7 F 1.0 Carter & Evans 563 UK cases 5:1 3/1.000 1st degree 76%; 2nd degree 13.2, 11, 43.7, 37.8, 20.2, 17.2, 8, 5.3, 27.4, 20, 15.3, 11.1, NR NR (1969a)‡32 M 5.0 27%; 3rd degree 50% 24 70 34.3 21.5 63.3 18.6 F 1.0 Carter & Evans 426 UK cases 5:1 3/1.000 1st degree 76%; 2nd degree NR NR NR 13.5, 9.9, 12.8, 15.5, 13.3, 11.4, NR NR (1969b)‡32 M 5.0 27%; 3rd degree 50% 31.6 NR 23 F 1.0 McKeown et al. 489 UK cases 4.2:1 3/1.000 NR NR NR NR 18.5, 19.4, 8.8, 9.5, 16.9, 17.4, NR NR (1951)‡ 119 M 4.7 19.3 NR 16.6 F 1.1 *Risks are displayed as sex specific rate ratios (incidence in relatives/incidence in reference population according to sex). ‡Included in the re-analysis by Mitchell et al.37 §Male and female incidence rates were estimated by the authors of this actual paper based on the given overall incidence rate and sex ratio. Risk ratios were calculated based on data provided Table 3 | Neuromuscular and connective tissue syndromes associated with IHPS by Mitchell et al.37 Abbreviations: IHPS, infantile hypertrophic pyloric stenosis; F, female; M, male. Syndrome OMIM Mayor Inheritance Gene/ Incidence Number manifestations chromosome syndrome* of IHPS region cases (n) Neuromuscular disorders Congenital 613327 Congenital AR PTRF/17q21 1:25,000– 5–10 generalized generalized 100,000 lipodystrophy lipodystrophy, ECG type IV121 abnormalities, muscular dystrophy X-linked myotubular 310400 Congenital XL MTM1/Xq28 1:25,000– 1–4 myopathy-171 hypotonia, facial 100,000 diplegia, myopathy Marden–Walker 248700 Microcephaly, AR Unknown 1:100,000– 1–4 syndrome‡122 blepharophimosis, 1,000,000 joint contractures Paramyotonia 168300 Prolonged myotonia AD SCN4A/17q23 1:25,000– 1–4 congenita123 induced by exposure 100,000 to cold, inability to relax muscles Connective tissue Apert syndrome 124 101200 Craniosynostosis, AD FGFR2/10q26 1:65,000 1–4 complete syndactyly of fingers and toes Beare–Stevenson 123790 Craniosynostosis, AD FGFR2/10q26 1:100,000– 1–4 syndrome125 acanthosis nigricans, 1,000,000 cutis gyrata
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Table 3 | Cont. Syndrome OMIM Mayor Inheritance Gene/ Incidence Number manifestations chromosome syndrome* of IHPS region cases (n) Nephrotic syndrome 256300 Proteinuria, renal AR NPHS1/19q13 1:25,000– 5–10 type 1126 failure 100,000 (1:8,000 in Finland) Denys–Drash 194080 Proteinuria, AR W T1/11p13 1:25,000– 1–4 syndrome127 ambiguous genitalia, 100,000 Wilms tumour Ehlers–Danlos 130020 Joint hypermobility AD TNXB/6p21 1:10,000– 1–4 type III73-76 25,000 Ehlers–Danlos 130050 Vascular fragility, AD, AR COL3A1/2q32 1:100,000– 1–4 type IV128 thin skin, prominent 1,000,000 eyes, thin nose, decreased subcutaneous fat Kallmann syndromeb89 308700, Anosmia, AD, AR, KAL1/Xp22, 1:10,000– 1–4 147950, hypogonadotropic XL, M FGFR1/8p11 25,000 607123, hypogonadism PROKR2/20p12, 607002, PROK2/3p13, 600483, CHD7/8q12, 608892 FGF8/10q24, WDR11/10q26 Knobloch syndrome 608454 Myopia, retinal unknown Unknown 1:100,000– 1–4 type 2129 detachment, 1,000,000 encephalocele Osteoglophonic 166250 Craniosynostosis, AD FGFR1/8p11 <1:1,000,000 1–4 dwarfism130 short stature, skeletal dysplasia Pfeiffer syndrome131 101600 Craniosynostosis, AD FGFR1/8p11, 1:100,000– 1–4 broad thumbs FGFR2/10q26 1,000,000 and big toes, syndactylies X-linked intellectual 300799 Intellectual disability, XL ZDHHC9/Xq26 1:100,000– 1–4 disability, ZDHHC9- marfanoid habitus 1,000,000 related132 For further information about the syndromes in the Table, please use the (freely available) internet sites of OMIM (www.ncbi.nlm.nih.gov/omim), Genereviews (www.ncbi.nlm.nih.gov/sites/GeneTests/review) and Orphanet (www. orpha.net) or the most commonly used textbook ‘Gorlin’s Syndromes of the Head and Neck’.133 *Estimated incidence of entity according to OMIM and Gorlin’s Syndromes of the Head and Neck. ‡No classical pyloric stenosis; elongation of pyloric channel. §Kallmann syndrome is also mentioned in the ciliopathies. Abbreviations: AD, autosomal dominant; AR, autosomal recessive; ECG, electrocardiography; IHPS, infantile hypertrophic pyloric stenosis; M, microdeletion; OMIM, online mendelian inheritance in man; XL, X-linked.
62 Infantile hypertrophic pyloric stenosis-genetics and syndromes
Table 4 | Metabolic syndromes and signalling disturbances associated with IHPS Syndrome OMIM Mayor manifestations Inheritance Gene/ Incidence Number Chapter chromosome syndrome* of IHPS region cases (n) Metabolic De Barsy 614438 Cutis laxa, AR PYCR1/17q25 1:100,000– 1–4 syndrome134 progeroid features, 1,000,000 2 ophathalmological abnormalities, intrauterine growth retardation Phenylketonuria67 261600 Intellectual disability, AR PAH/12q23 1:10,000 5–10 abnormal gait, eczema, epilepsy Smith–Lemli–Opitz 270400 Intellectual disability, AR DHCR7/11q13 1:25,000 11–50 syndrome78, 79, 135 failure to thrive, unusual face, skeletal, genital and organ malformations, gastrointestinal motility disorders X-linked 308100 Ichthyosis, corneal XL, M STS/Xp22 1:6,000 males 5–10 ichthyosis136-138 opacities, behavioural problems Zellweger 214100 Extreme hypotonia, AR PEX1/7q21, 1:35,000 1–4 syndrome139, 140 seizures, tall forehead, PEX2/8q21, retinopathy, hepatic PEX3/6q23, dysfunction, renal cysts PEX5/12p13, PEX6/6p21, PEX10/1p36, PEX12/17q12, PEX13/2p15, PEX14/1p36, PEX16/11p12, PEX19/1q22, PEX26/22q11 Intracellular signalling pathway disturbances Chronic idiopathic 300048 Abnormal XL FLNA/Xq28 1:100,000– 1–4 intestinal pseudo- gastrointestinal 1,000,000 obstruction141, 142 mobility, short bowel, hydronephrosis Dextro-looped 608808 Complete inversion of S CFC1/2q21 1:25,000– 1–4 transposition of the the great vessels 100,000 great arteries-2143 FG syndrome144 305450, Hypotonia, XL MED12/Xq13, 1:100,000– 5–10 300321, macrocephaly, anal FLNA/Xq28, 1,000,000 300406, malformations, FGS3/Xp22, 300422, constipation FGS4/Xp11, 300581 FGS5/Xq22 Osteopathia 300373 Metaphyseal striations, XL FAM123B/Xq11 1:100,000– 1–4 striata with cranial macrocephaly, cranial 1,000,000 sclerosis145 sclerosis Ulnar-mammary 181450 Ulnar ray defects, AD TBX3/12q24 1:100,000– 1–4 syndrome146 underdeveloped 1,000,000 mammae, obesity Visceral neuropathy 243180 Chronic intestinal AR, AD Unknown <1:1,000,000 5–10 (familial) 147 pseudo-obstruction
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X-linked 300049 Periventricular XL FLNA/Xq28 1:100,000– 1–4 periventricular heterotopic nodules, 1,000,000 heterotopia81 intellectual disability Intercellular communication disturbances Hypoplastic left heart 241550 Hypoplastic left heart AR, GJA1/6q21 1:25,000– 1–4 syndrome84 multifactorial 100,000 Autosomal dominant 173900 Late-onset renal cysts, AD PKD1/4q22, 1:2,500 1–4 polycystic kidney 613095 renal failure, intracranial PKD2/16p13 disease148 aneurysm For further information about the syndromes in the Table, please use the (freely available) internet sites of OMIM (www.ncbi.nlm.nih.gov/omim), Genereviews (www.ncbi.nlm.nih.gov/sites/GeneTests/review) and Orphanet (www. orpha.net) or the most commonly used textbook ‘Gorlin’s Syndromes of the Head and Neck’.133 *Estimated incidence of entity according to OMIM and Gorlin’s Syndromes of the Head and Neck. Abbreviations: AD, autosomal dominant; AR, autosomal recessive; IHPS, infantile hypertrophic pyloric stenosis; M, microdeletion; OMIM, online mendelian inheritance in man; S, sporadic; XL, X-linked.
Table 5 | Ciliopathies and disturbances of gene regulation associated with IHPS Syndrome OMIM Mayor Inheritance Gene/ Incidence Number manifestations chromosome syndrome* of IHPS region cases (n) Ciliopathies Beemer–Langer 269860 Dwarfism, oedema, AR Unknown <1:1,000,000 1–4 syndrome149 macrocephaly, cleft lip, small external genitalia, dysostosis Kallmann 308700, Anosmia, AD, AR, KAL1/Xp22, 1:10,000– 1–4 syndrome†89 147950, hypogonadotropic XL, M FGFR1/8p11, 25,000 607123, hypogonadism PROKR2/20p12, 607002, PROK2/3p13, 600483, CHD7/8q12, 608892 FGF8/10q24, WDR11/10q26 Autosomal recessive 263200 Cystic kidneys, AR PKHD1/6p12 1:10,000 1–4 polycystic kidney respiratory failure, disease150 fibrosis of liver, biliary duct hyperplasia DNA-repair disturbances Cornelia de Lange 122470 Intellectual disability, AD, XL, S NIPBL/5p13, 1:80,000 11–50 syndrome90-92 prenatal and postnatal SMC1A/Xp11 growth retardation, unusual face, small hands, limb defects Chromosome 2q37 600430 Intellectual disability, AD, M HDAC4/2q37 1:100,000– 1–4 deletion syndrome151 round face, 1,000,000 brachydactyly, seizures Glomerulonephritis 137940 Glomerulonephritis, AD Unknown <1:1,000,000 1–4 with sparse hair and sparse hair, telangiectases‡152 telangiectasias Lenz microphthalmia153 309800, Microphthalmia, XL MA A/Xq27, <1:1,000,000 1–4 300166 colobomas of the iris, BCOR/Xp11 simple ears, clefting, narrow shoulders, digital anomalies
64 Infantile hypertrophic pyloric stenosis-genetics and syndromes
Table 5 | Cont. Chapter Syndrome OMIM Mayor Inheritance Gene/ Incidence Number manifestations chromosome syndrome* of IHPS region cases (n) Rothmund–Thomson 268400 Poikiloderma, AR RECQL4/8q24 1:25,000– 1–4 syndrome154 photosensitivity, 100,000 cataract, growth 2 failure, thumb anomalies Simpson-Golabi-Behmel 312870 Prenatal and postnatal XL GPC3/Xq26 1:25,000– 1–4 syndrome type 1§155 overgrowth, coarse 100,000 face, congenital heart defects, diaphragmatic hernia, intellectual disability Transcription regulation disorder Renal cysts-diabetes 137920 Renal cysts, renal and AD HNF1B/17q12 1:10,000– 1–4 syndrome96 genital malformations, 25,000 diabetes, gout MAPK-pathway disturbances Costello 218040 High birth AD HR AS/11p15 1:25,000– 5–10 syndrome99, 156 weight, unusual 100,000 face, periorificial papillomata, cardiomyopathy, short stature, intellectual disability Noonan 163950 Short stature, unusual AD PTPN11/12q24, 1:1,000 1–4 syndrome157 face, webbed neck, KRAS/12p12, pulmonary stenosis, SOS1/2p22, pectus excavatum, RAF1/3p25, bleeding diathesis NRAS/1p13.2 For further information about the syndromes in the Table, please use the (freely available) internet sites of OMIM (www.ncbi.nlm.nih.gov/omim), Genereviews (www.ncbi.nlm.nih.gov/sites/GeneTests/review) and Orphanet (www. orpha.net) or the most commonly used textbook ‘Gorlin’s Syndromes of the Head and Neck’.133 *Estimated incidence of entity according to OMIM and Gorlin’s Syndromes of the Head and Neck. †Kallmann syndrome is also mentioned in the connective tissue syndromes. ‡Probably allelic to Rothmund-Thomson syndrome. §Not truly a DNA disturbance but involved in cell division control, growth regulation and apoptosis. Abbreviations: AD, autosomal dominant; AR, autosomal recessive; IHPS, infantile hypertrophic pyloric stenosis; M, microdeletion; OMIM, online mendelian inheritance in man; S, sporadic; XL, X-linked.
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Table 6 | Lymphatic abnormalities and syndromes of environmental and unknown origin associated with IHPS Syndrome OMIM Mayor Inheritance Gene/ Incidence Number manifestations chromosome syndrome* of IHPS region cases (n) Lymphatic abnormalities Cantú 239850 Hypertrichosis, AR, AD Unknown 1:100,000– 1–4 syndrome104 osteodysplasia, 1,000,000 cardiomegaly, intellectual disability, lymphoedema Congenital 603523 Congenital chylothorax AR Unknown 1:25,000– 1–4 chylothorax106 100,000 Lymphoedema- 235510 Intestinal AR CCBE1/18q21 1:25,000– 1–4 Lymphangiectasia- lymphangiectasia, 100,000 Intellectual disability lymphoedema, unusual syndrome158, 159 face, intellectual disability Environmental Fetal alcohol NA Prenatal and postnatal E Unknown 1:800 5–10 syndrome18, 19, 107 growth retardation, microcephaly, unusual face, intellectual disability Fetal penicillamine NA Cutis laxa, contractures, E Unknown 1:100,000– 1–4 embryopathy160 CNS abnormalities, 1,000,000 inguinal hernia Unknown Arthrogryposis, Perthes NA Arthrogryposis, upward AR Unknown <1:1,000,000 1–4 disease and upward gaze palsy, avascular gaze palsy161 necrosis of capital femoral epiphysis, atopy, congenital heart disease Crow NA Agammaglobulinaemia, AR Unknown <1:1,000,000 1–4 syndrome162 microcephaly, craniosynostosis, cleft palate Fine–Lubinsky 601353 Brachycephaly, cataract, AR Unknown <1:1,000,000 1–4 syndrome163 deafness, microstomia, brachydactyly, intellectual disability Fryns 229850 Diaphragmatic hernia, AR Unknown 1:12,000 1–4 syndrome164 unusual face, distal limb anomalies Harrod 601095 Thin body build, narrow AR Unknown <1:1,000,000 1–4 syndrome165, 166 face, arachnodactyly, megacolon, intellectual disability Kaufman 244450 Microcephaly, AR Unknown <1:1,000,000 1–4 oculocerebrofacial hypertelorism, syndrome167 microcornea, myopia, unusual face, intellectual disability Lowry–Maclean 600252 Congenital heart disease, AD Unknown <1:1,000,000 1–4 syndrome168 diaphragmatic hernia, clefting, intellectual disability
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Split hand/foot with 119100 Tibial aplasia, split AR, AD SHFL1/1q42‡ 1:25,000– 1–4 tibial defects169 hand/foot deformities, 100,000 Chapter postaxial polydactyly, malformed ears Toriello–Carey 217980 Hypotonia, cleft palate, AR Unknown 1:100,000– 1–4 syndrome170 heart defects, agenesis 1,000,000 corpus callosum, unusual 2 face, intellectual disability Yunis-Varón 216340 Ossification defects of AR Unknown 1:100,000– 1–4 syndrome171 skull and clavicles, absent 1,000,000 thumbs and halluces, alopecia For further information about the syndromes in the Table, please use the (freely available) internet sites of OMIM (www.ncbi.nlm.nih.gov/omim), Genereviews (www.ncbi.nlm.nih.gov/sites/GeneTests/review) and Orphanet (www. orpha.net) or the most commonly used textbook ‘Gorlin’s Syndromes of the Head and Neck’.133 *Estimated incidence of entity according to OMIM and Gorlin’s Syndromes of the Head and Neck. ‡Function of gene completely unknown. Abbreviations: AD, autosomal dominant; AR, autosomal recessive; CNS, central nervous system; E: environmental; IHPS, infantile hypertrophic pyloric stenosis; NA, not applicable; OMIM, online mendelian inheritance in man.
Table 7 | Chromosomal abnormalities associated with IHPS Syndrome OMIM Mayor manifestations Incidence Number of IHPS syndrome* cases (n) Deletion 1q25172 NA Microdolichocephaly, unusual face, <1:1,000,000 1–4 digital anomalies, intellectual disability Maternal uniparental NA Prenatal and postnatal growth <1:1,000,000 1–4 disomy 2173 retardation, unusual face, renal failure Deletion 3q29174 609425 growth retardation, unusual face, <1:1,000,000 1–4 intellectual disability Translocation (8;17)(q24;q25) NA Intellectual disability, developmental <1:1,000,000 1–4 175 delay, unusual face, dysmorphic features, epilepsy, behavioural problems Duplication 9q (inv insert (12;9) NA Unusual face, preauricular pits, <1:1,000,000 1–4 (p13;q23q13) abnormalities of hands, hypertonia, maternal) 39 intellectual disability Translocation (10;13) NA Growth retardation, unusual face, heart <1:1,000,000 1–4 (p15.1;q34) 176 defect, inguinal hernia, intellectual disability Deletion 10p13177 NA Microcephaly, micrognathia, congenital <1:1,000,000 1–4 heart disease, unusual face, intellectual disability Deletion 11q23178 147791 growth retardation, trigonocephaly, <1:1,000,000 1–4 eye abnormalities, thrombocytopenia, intellectual disability Partial trisomy 13q22, partial NA Unusual face, anomalies of hands and <1:1,000,000 1–4 monosomy 18q21179 feet, heart defects Trisomy 13180 NA Growth retardation, clefting, occipital 1:12,000 1–4 skin defects, brain malformations, cardiac anomalies, anomalies of hand and feet, intellectual disability Duplication 14q/deletion NA Hypotonia, short stature, unusual face, <1:1,000,000 1–4 14q181 intellectual disability Trisomy 18180 NA Unusual face, cardiac and central <1:1,000,000 5–10 nervous system abnormalities, omphalocele, intellectual disability
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Deletion 18qter182 133705 Narrow external auditory canal, vertical <1:1,000,000 1–4 talus, hypertelorism, anal atresia, intellectual disability Deletion 20q11183 NA Prenatal growth retardation, postnatal <1:1,000,000 1–4 overgrowth, unusual face, intellectual disability Trisomy 21184, 185 190685 Hypotonia,, unusual face, cardiac 1:800 >50 anomalies, Hirschsprung disease, growth retardation, intellectual disability Mosaicism 45,X/46, XX186 NA Gonadal dysgenesis, short stature, 1:7,500 females 1–4 cardiovascular abnormalities, kidney malformations For further information about the syndromes in the Table, please use the (freely available) internet sites of OMIM (www.ncbi.nlm.nih.gov/omim), Genereviews (www.ncbi.nlm.nih.gov/sites/GeneTests/review) and Orphanet (www. orpha.net) or the most commonly used textbook ‘Gorlin’s Syndromes of the Head and Neck’.133 *Estimated incidence of entity according to OMIM and Gorlin’s Syndromes of the Head and Neck. Abbreviations: IHPS, infantile hypertrophic pyloric stenosis; NA, not applicable; OMIM, online mendelian inheritance in man.
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89. Weissortel,R., Strom,T.M., Dorr,H.G., Rauch,A., & Meitinger,T. Analysis of an interstitial deletion in a patient with Kallmann syndrome, X-linked ichthyosis and mental retardation. Clin. Genet. 54, 45-51 (1998). Chapter 90. Hennekam,R.C., Krantz,I.D., & Allanson,J.E. Cornelia de Lange syndrome (Brachmann-de Lange syndrome) in Gorlin’s Syndromes of the Head and Neck 428-434 (Oxford University Press, New York, 2010). 91. Jackson,L., Kline,A.D., Barr,M.A., & Koch,S. de Lange syndrome: a clinical review of 310 individuals. Am. J. Med. Genet. 47, 940-946 (1993). 2 92. Krantz,I.D. et al. Cornelia de Lange syndrome is caused by mutations in NIPBL, the human homolog of Drosophila melanogaster Nipped-B. Nat. Genet. 36, 631-635 (2004). 93. Oliveira,J. et al. Development of NIPBL locus-specific database using LOVD: from novel mutations to further genotype-phenotype correlations in Cornelia de Lange Syndrome. Hum. Mutat. 31, 1216-1222 (2010). 94. Bingham,C. & Hattersley,A.T. Renal cysts and diabetes syndrome resulting from mutations in hepatocyte nuclear factor-1beta. Nephrol. Dial. Transplant. 19, 2703-2708 (2004). 95. Bingham,C. et al. Mutations in the hepatocyte nuclear factor-1beta gene are associated with familial hypoplastic glomerulocystic kidney disease. Am. J. Hum. Genet. 68, 219-224 (2001). 96. Kaplan,B.S., Gordon,I., Pincott,J., & Barratt,T.M. Familial hypoplastic glomerulocystic kidney disease: a definite entity with dominant inheritance. Am. J. Med. Genet. 34, 569-573 (1989). 97. Wang,D., Braendstrup,O., Larsen,S., Horn,T., & Strandgaard,S. The expression and activity of renal nitric oxide synthase and circulating nitric oxide in polycystic kidney disease rats. APMIS 112, 358-368 (2004). 98. Hennekam,R.C. Costello syndrome: an overview. Am. J. Med. Genet. C. Semin. Med. Genet. 117C, 42-48 (2003). 99. Gripp,K.W. et al. Costello syndrome associated with novel germline HRAS mutations: an attenuated phenotype? Am. J. Med. Genet. A 146A, 683-690 (2008). 100. BLUMENTHAL,O. [Pyloristenosis caused by a neurofibroma in a case of Recklinghausen’s disease]. Chirurg 21, 313-314 (1950). 101. Alders,M. et al. Evaluation of clinical manifestiations in patients with severe lymphedema with and without CCBE1 mutations. Eur.J.Med.Genet. 2011. Ref Type: In Press 102. Alders,M. et al. Mutations in CCBE1 cause generalized lymph vessel dysplasia in humans. Nat. Genet. 41, 1272-1274 (2009). 103. Hogan,B.M. et al. Ccbe1 is required for embryonic lymphangiogenesis and venous sprouting. Nat. Genet. 41, 396-398 (2009). 104. Engels,H. et al. Further case of Cantu syndrome: exclusion of cryptic subtelomeric chromosome aberrations. Am. J. Med. Genet. 111, 205-209 (2002). 105. Scarcella,A., De,L.A., Pasquariello,M.B., & Gambardella,P. Early death in two sisters with Hennekam syndrome. Am. J. Med. Genet. 93, 181-183 (2000). 106. Fox,G.F., Challis,D., O’Brien,K.K., Kelly,E.N., & Ryan,G. Congenital chylothorax in siblings. Acta Paediatr. 87, 1010-1012 (1998). 107. Mangyanda,M.K. et al. [Fetal alcohol syndrome and hypertrophic pyloric stenosis in two brothers]. Arch. Pediatr. 5, 695-696 (1998). 108. Schmickel,R.D. Contiguous gene syndromes: a component of recognizable syndromes. J. Pediatr. 109, 231-241 (1986). 109. Miller,D.T. et al. Consensus statement: chromosomal microarray is a first-tier clinical diagnostic test for individuals with developmental disabilities or congenital anomalies. Am. J. Hum. Genet. 86, 749-764 (2010). 110. Feenstra,B. et al. Common variants near MBNL1 and NKX2-5 are associated with infantile hypertrophic pyloric stenosis. Nat. Genet.(2012).
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111. Xu,B. et al. Exome sequencing supports a de novo mutational paradigm for schizophrenia. Nat. Genet. 43, 864-868 (2011). 112. Hennekam,R.C. Care for patients with ultra-rare disorders. Eur. J. Med. Genet. 54, 220-224 (2011). 113. Kaati,G., Bygren,L.O., & Edvinsson,S. Cardiovascular and diabetes mortality determined by nutrition during parents’ and grandparents’ slow growth period. Eur. J. Hum. Genet. 10, 682-688 (2002). 114. Manolio,T.A. et al. Finding the missing heritability of complex diseases. Nature 461, 747-753 (2009). 115. Hennekam,R.C. & Biesecker,L.G. Next generation sequencing demands next generation phenotyping. Hum. Mutat. 33, 884-886 (2012). 116. Czeizel,A. & Tusnady,G. Aetiological data of nine isolated common congenital abnormalities. 107-120. 1984. Budapest, Hungary, Akademiai Kiado. Aetiologic Studies of Isolated Common Congenital Abnormalities in Hungary. Ref Type: Report 117. Adelstein,P. & Fedrick,J. Pyloric stenosis in the Oxford Record Linkage Study area. J. Med. Genet. 13, 439-448 (1976). 118. Dodge,J.A. Infantile Hypertrophic Pyloric Stenosis. 1970. Cardiff, Wales, University of Wales. Ref Type: Thesis/Dissertation 119. MCKEOWN,T., MacMahon,B., & Record,R.G. The familial incidence of congenital pyloric stenosis. Ann. Eugen. 16, 260-281 (1951). 120. Everett,K.V. et al. Linkage of monogenic infantile hypertrophic pyloric stenosis to chromosome 16q24. Eur. J. Hum. Genet. 16, 1151-1154 (2008). 121. Rajab,A., Heathcote,K., Joshi,S., Jeffery,S., & Patton,M. Heterogeneity for congenital generalized lipodystrophy in seventeen patients from Oman. Am. J. Med. Genet. 110, 219-225 (2002). 122. Gossage,D., Perrin,J.M., & Butler,M.G. A 26-month-old child with Marden-Walker syndrome and pyloric stenosis. Am. J. Med. Genet. 26, 915-919 (1987). 123. Ay,B., Gercek,A., Dogan,V.I., Kiyan,G., & Gogus,Y.F. Pyloromyotomy in a patient with paramyotonia congenita. Anesth. Analg. 98, 68-9, table (2004). 124. BLANK,C.E. Apert’s syndrome (a type of acrocephalosyndactyly)-observations on a British series of thirty- nine cases. Ann. Hum. Genet. 24, 151-164 (1960). 125. Beare,J.M., Dodge,J.A., & Nevin,N.C. Cutis gyratum, acanthosis nigricans and other congenital anomalies. A new syndrome. Br. J. Dermatol. 81, 241-247 (1969). 126. Mahan,J.D., Mauer,S.M., Sibley,R.K., & Vernier,R.L. Congenital nephrotic syndrome: evolution of medical management and results of renal transplantation. J. Pediatr. 105, 549-557 (1984). 127. Hu,M. et al. A novel mutation of WT1 exon 9 in a patient with Denys-Drash syndrome and pyloric stenosis. Pediatr. Nephrol. 19, 1160-1163 (2004). 128. Kuivaniemi,H. et al. Identical G+1 to A mutations in three different introns of the type III procollagen gene (COL3A1) produce different patterns of RNA splicing in three variants of Ehlers-Danlos syndrome. IV. An explanation for exon skipping some mutations and not others. J. Biol. Chem. 265, 12067-12074 (1990). 129. Wilson,C., Aftimos,S., Pereira,A., & McKay,R. Report of two sibs with Knobloch syndrome (encephalocoele and viteroretinal degeneration) and other anomalies. Am. J. Med. Genet. 78, 286-290 (1998). 130. Keats,T.E., Smith,T.H., & Sweet,D.E. Craniofacial dysotosis with fibrous metaphyseal deffects. Am. J. Roentgenol. Radium. Ther. Nucl. Med. 124, 271-275 (1975). 131. Cohen,M.J.J. & Maclean,R.E. Craniosynostosis: diagnosis, evaluation and management. in Syndromes with craniosynostosis (eds. Cohen,M.J.J. & Maclean,R.E.) 309-441 (New York: Oxford University Press, 2000). 132. Raymond,F.L. et al. Mutations in ZDHHC9, which encodes a palmitoyltransferase of NRAS and HRAS, cause X-linked mental retardation associated with a Marfanoid habitus. Am. J. Hum. Genet. 80, 982-987 (2007).
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133. Hennekam,R.C., Krantz,I.D., & Allanson,J.E. Gorlin’s Syndromes of the Head and Neck(Oxford University Press, New York, 2010). Chapter 134. Lin,D.S. et al. Compound heterozygous mutations in PYCR1 further expand the phenotypic spectrum of De Barsy syndrome. Am. J. Med. Genet. A 155A, 3095-3099 (2011). 135. Cooper,M.K. et al. A defective response to Hedgehog signaling in disorders of cholesterol biosynthesis. Nat. Genet. 33, 508-513 (2003). 2 136. Garcia Perez A. & Crespo,M. X-linked ichthyosis associated with hypertrophic pyloric stenosis in three brothers. Clin. Exp. Dermatol. 6, 159-161 (1981). 137. Stoll,C., Grosshans,E., Binder,P., & Roth,M.P. Hypertrophic pyloric stenosis associated with X-linked ichthyosis in two brothers. Clin. Exp. Dermatol. 8, 61-64 (1983). 138. Bruno,L., Bocanegra,O., & Magnelli,N. Recessive X-linked ichthyosis associated with hypertrophic pyloric stenosis: a chance occurrence? Clin. Exp. Dermatol. 28, 74-76 (2003). 139. Grayer,J. Recognition of Zellweger syndrome in infancy. Adv. Neonatal Care 5, 5-13 (2005). 140. Powers,J.M. The pathology of peroxisomal disorders with pathogenetic considerations. J. Neuropathol. Exp. Neurol. 54, 710-719 (1995). 141. Tanner,M.S., Smith,B., & Lloyd,J.K. Functional intestinal obstruction due to deficiency of argyrophil neurones in the myenteric plexus. Familial syndrome presenting with short small bowel, malrotation, and pyloric hypertrophy. Arch. Dis. Child 51, 837-841 (1976). 142. Auricchio,A. et al. The locus for a novel syndromic form of neuronal intestinal pseudoobstruction maps to Xq28. Am. J. Hum. Genet. 58, 743-748 (1996). 143. Goldmuntz,E. et al. CFC1 mutations in patients with transposition of the great arteries and double-outlet right ventricle. Am. J. Hum. Genet. 70, 776-780 (2002). 144. Battaglia,A., Chines,C., & Carey,J.C. The FG syndrome: report of a large Italian series. Am. J. Med. Genet. A 140, 2075-2079 (2006). 145. Rott,H.D., Krieg,P., Rutschle,H., & Kraus,C. Multiple malformations in a male and maternal osteopathia strata with cranial sclerosis (OSCS). Genet. Couns. 14, 281-288 (2003). 146. Schinzel,A., Illig,R., & Prader,A. The ulnar-mammary syndrome: an autosomal dominant pleiotropic gene. Clin. Genet. 32, 160-168 (1987). 147. Tanner,M.S., Smith,B., & Lloyd,J.K. Functional intestinal obstruction due to deficiency of argyrophil neurones in the myenteric plexus. Familial syndrome presenting with short small bowel, malrotation, and pyloric hypertrophy. Arch. Dis. Child 51, 837-841 (1976). 148. Loh,J.P., Haller,J.O., Kassner,E.G., Aloni,A., & Glassberg,K. Dominantly-inherited polycystic kidneys in infants: association with hypertrophic pyloric stenosis. Pediatr. Radiol. 6, 27-31 (1977). 149. Balci,S. et al. Familial short rib syndrome, type Beemer, with pyloric stenosis and short intestine, one case diagnosed prenatally. Clin. Genet. 39, 298-303 (1991). 150. Kaplan,B.S., Fay,J., Shah,V., Dillon,M.J., & Barratt,T.M. Autosomal recessive polycystic kidney disease. Pediatr. Nephrol. 3, 43-49 (1989). 151. Falk,R.E. & Casas,K.A. Chromosome 2q37 deletion: clinical and molecular aspects. Am. J. Med. Genet. C. Semin. Med. Genet. 145C, 357-371 (2007). 152. Sherwood,M.C., Pincott,J.R., Goodwin,F.J., & Dillon,M.J. Dominantly inherited glomerulonephritis and an unusual skin disease. Arch. Dis. Child 62, 1278-1280 (1987). 153. Forrester,S., Kovach,M.J., Reynolds,N.M., Urban,R., & Kimonis,V. Manifestations in four males with and an obligate carrier of the Lenz microphthalmia syndrome. Am. J. Med. Genet. 98, 92-100 (2001). 154. Hilhorst-Hofstee,Y. et al. Radial aplasia, poikiloderma and auto-immune enterocolitis--new syndrome or severe form of Rothmund-Thomson syndrome? Clin. Dysmorphol. 9, 79-85 (2000).
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155. Konig,R., Fuchs,S., Kern,C., & Langenbeck,U. Simpson-Golabi-Behmel syndrome with severe cardiac arrhythmias. Am. J. Med. Genet. 38, 244-247 (1991). 156. Johnson,J.P. et al. Costello syndrome: phenotype, natural history, differential diagnosis, and possible cause. J. Pediatr. 133, 441-448 (1998). 157. Barberia,L.E., Saavedra,O.D., & Maroto,E.M. Etiopathogenic analysis of the caries on three patients with Noonan Syndrome. Med. Oral 8, 136-142 (2003). 158. Scarcella,A., De,L.A., Pasquariello,M.B., & Gambardella,P. Early death in two sisters with Hennekam syndrome. Am. J. Med. Genet. 93, 181-183 (2000). 159. Van Balkom,I.D. et al. Lymphedema-lymphangiectasia-mental retardation (Hennekam) syndrome: a review. Am. J. Med. Genet. 112, 412-421 (2002). 160. Pinter,R., Hogge,W.A., & McPherson,E. Infant with severe penicillamine embryopathy born to a woman with Wilson disease. Am. J. Med. Genet. A 128A, 294-298 (2004). 161. Alkuraya,F.S. Arthrogryposis, perthes disease, and upward gaze palsy: A novel autosomal recessive syndromic form of arthrogryposis. Am. J. Med. Genet. A(2010). 162. Crow,Y.J. et al. A newly recognized, likely autosomal recessive syndrome comprising agammaglobulinemia, microcephaly, craniosynostosis, severe dermatitis, and other features. Am. J. Med. Genet. A 140, 1131- 1135 (2006). 163. Suthers,G.K., Earley,A.E., & Huson,S.M. A distinctive syndrome of brachycephaly, deafness, cataracts and mental retardation. Clin. Dysmorphol. 2, 342-345 (1993). 164. Ayme,S. et al. Fryns syndrome: report on 8 new cases. Clin. Genet. 35, 191-201 (1989). 165. Harrod,M.J., Keele,D.K., & Howard,J., Sr. A syndrome of craniofacial, digital, and genital anomalies. Birth Defects Orig. Artic. Ser. 13, 111-115 (1977). 166. Jurenka,S.B. & Van Allen,M.I. Additional case of craniofacial and digital anomalies as reported by Harrod et al. Am. J. Med. Genet. 61, 168-170 (1996). 167. Jurenka,S.B. & Evans,J. Kaufman oculocerebrofacial syndrome: case report. Am. J. Med. Genet. 3, 15-19 (1979). 168. Lowry,R.B. & MacLean,J.R. Syndrome of mental retardation, cleft palate, eventration of diaphragm, congenital heart defect, glaucoma, growth failure and craniosynostosis. Birth Defects Orig. Artic. Ser. 13, 203-228 (1977). 169. van de Kamp,J.M. et al. Bifurcation of the femur with tibial agenesis and additional anomalies. Am. J. Med. Genet. A 138, 45-50 (2005). 170. Toriello,H.V. et al. Toriello-Carey syndrome: delineation and review. Am. J. Med. Genet. A 123A, 84-90 (2003). 171. Rabe,H. et al. Yunis-Varon syndrome: the first case of German origin. Clin. Dysmorphol. 5, 217-222 (1996). 172. Steinbach,P., Wolf,M., & Schmidt,H. Multiple congenital anomalies/mental retardation (MCA/MR) syndrome due to interstitial deletion 1q. Am. J. Med. Genet. 19, 131-136 (1984). 173. Webb,A.L. et al. Maternal uniparental disomy for chromosome 2 in association with confined placental mosaicism for trisomy 2 and severe intrauterine growth retardation. Prenat. Diagn. 16, 958-962 (1996). 174. Tyshchenko,N. et al. 1.6Mb deletion in chromosome band 3q29 associated with eye abnormalities. Eur. J. Med. Genet. 52, 128-130 (2009). 175. Hodgson,S.V., Berry,A.C., & Dunbar,H.M. Two brothers with an unbalanced 8;17 translocation and infantile pyloric stenosis. Clin. Genet. 48, 328-330 (1995). 176. Roos,A. et al. Submicroscopic unbalanced translocation resulting in del10p/dup13q detected by subtelomere FISH. Eur. J. Med. Genet. 49, 505-510 (2006). 177. Shokeir,M.H., Ray,M., Hamerton,J.L., Bauder,F., & O’Brien,H. Deletion of the short arm of chromosome No. 10. J. Med. Genet. 12, 99-103 (1975).
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178. Favier,R. et al. Paris-Trousseau syndrome : clinical, hematological, molecular data of ten new cases. Thromb. Haemost. 90, 893-897 (2003). Chapter 179. Cekada,S. et al. Partial trisomy 13q22-->qter and monosomy 18q21-->qter as a result of familial translocation. Acta Paediatr. 88, 675-678 (1999). 180. Taylor,A.I. Autosomal trisomy syndromes: a detailed study of 27 cases of Edwards’ syndrome and 27 cases of Patau’s syndrome. J. Med. Genet. 5, 227-252 (1968). 2 181. Chen,C.P. et al. A paternally derived inverted duplication of distal 14q with a terminal 14q deletion. Am. J. Med. Genet. A 139A, 146-150 (2005). 182. Rasmussen,N., Johnsen,N.J., & Thomsen,J. Inherited congenital bilateral atresia of the external auditory canal, congenital bilateral vertical talus and increased interocular distance. Acta Otolaryngol. 88, 296-302 (1979). 183. Callier,P. et al. Major feeding difficulties in the first reported case of interstitial 20q11.22-q12 microdeletion and molecular cytogenetic characterization. Am. J. Med. Genet. A 140A, 1859-1863 (2006). 184. Moore,S.W. Down syndrome and the enteric nervous system. Pediatr. Surg. Int. 24, 873-883 (2008). 185. Freeman,S.B. et al. Congenital gastrointestinal defects in Down syndrome: a report from the Atlanta and National Down Syndrome Projects. Clin. Genet. 75, 180-184 (2009). 186. Van der Horst,R., Frankel,J., & Grace,J. Congenital hypertrophic pyloric stenosis in phenotypic female twins with X-XX mosaicism. Arch. Dis. Child 46, 554-556 (1971).
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Chapter 3
Seasonal variations in the incidence of infantile hypertrophic pyloric stenosis in two Dutch regions
Babette Peeters, Matthijs W. Oomen, Hein A.M. Daanen, Marian K. Bakker, Doeke Boersma, Rob W. Meijer, Marc A. Benninga, Hugo A. Heij, Raoul C. Hennekam
Submitted chapter 3
Abstract Objective Seasonal variations in the incidence of infantile hypertrophic pyloric stenosis (IHPS) have been reported, but results have been contradictory and local factors have generally not been taken into account. The aim of this study was to investigate seasonal variations in IHPS incidence in two closely located but separate regions of a small country.
Study design We studied IHPS children born between 1995 and 2009 in two regions of the Netherlands using hospital databases and a birth defect registry. Yearly, seasonal and monthly variations in IHPS incidence by date of birth were assessed by Chi square analyses and Walter and Elwood’s test for seasonality while correcting for the total number of live births. Correlation analyses were performed for local climate factors.
Results In North-Holland, 612/475,941 (1.29/1,000) children developed IHPS, compared to 355/287,207 (1.24/1,000) in the Northern Netherlands. In North-Holland only, significant seasonal variation was found with a peak incidence in children born in December (p = .005). Only a weak correlation was found between incidence rates and climate factors for this region, and no significant correlation was found for the Northern Netherlands. There was no change in IHPS incidence over time during the study period.
Conclusions We found a significant difference in IHPS incidence within the various parts of the year in one region, correlating weakly with local climate factors, and found significant differences between two closely located populations. Season specific environmental influences other than climate are likely to be involved in the pathophysiology of IHPS.
80 Seasonal variations in IHPS incidence
Introduction Infantile hypertrophic pyloric stenosis (IHPS) is a common condition in infants characterized by an acquired narrowing of the pylorus.1 A progressive hypertrophy of the pyloric muscle results in a near-complete obstruction of the pylorus, causing the classical symptom forceful projectile postprandial vomiting. IHPS typically occurs between the third and sixth week of life in a formerly healthy infant.2 Chapter The incidence of IHPS varies between 1.5-2 per thousand live births in the Western World and has a striking male predominance (male : female ratio 4-5:1).3 Despite its relatively high incidence, the etiology of isolated IHPS is still poorly understood. The cause is suggested 3-5 3 to be multifactorial, with an important role for genetic factors. Environmental factors, such as medication use, maternal age, maternal smoking and maternal drinking and feeding habits have been studied but the exact significance of most of these factors for developing IHPS remains unknown.3;4 Several studies have reported seasonal variation in the incidence of IHPS, suggesting that extrinsic factors anywhere from conception to early postnatal life influence the anatomy of the pyloric muscle.6 -11 Results of seasonal IHPS studies have been contradictory however, and some papers reported no seasonal variation in IHPS incidence.12-20 Complicating factors in comparing and interpreting results are the differences in definitions of seasons and differences in moments of measurement of incidences. Moreover, data come from various countries with important differences in climate and, thus, in seasonal characteristics, but also in genetic make-up, nutrition and cultural habits, complicating identification of shared associated influences. We reasoned that further insight in possible seasonal influences in IHPS might be obtained by studying IHPS incidences in two different regions in a single country, as these regions will share many possibly confounding factors and causes of differences (if present) might be more easily determined. Therefore, we studied the incidence of IHPS in two regions of the Netherlands over a period of 15 years, with detailed attention to various local climate factors.
Methods
Study population The Netherlands is a small, densely populated country (16,800,000 inhabitants; 404 inhabitants/km2). We studied children born in the province of North-Holland and the provinces Groningen, Friesland, Drenthe (Northern Netherlands) between 01.01.1995 and 31.12.2009 (Fig I). The province of North-Holland in the Northwestern part of the Netherlands is a densely populated province (2,600,000 inhabitants; 980 inhabitants/km2) with a high rate of
81 chapter 3
Figure I | Map of the Netherlands with the two study regions immigrants (mean immigration rate of 9.8/1,000 inhabitants between 1995 and 2009).21 Pediatric surgical care is centered exclusively in the two academic centers in the province (both in Amsterdam) in which care is provided by a joint, single team of pediatric surgeons, and the larger regional center (in Alkmaar). Patients presenting with IHPS at smaller regional hospitals are referred to any of these three hospitals. The Northern Netherlands consists of the three most northern located provinces of the country, and is the most rural area of the country with a low population density (1,700,00 inhabitants; 205 inhabitants/km2) and a relatively low rate of immigrants Dark grey colored area = North-Holland Light grey colored area = Northern Netherlands (mean immigration rate of 5.9/1,000 inhabitants between 1995 and 2009).21 Pediatric surgical care is provided in the single academic hospital of the Northern Netherlands but IHPS is also surgically corrected in various regional hospitals. We defined IHPS as an acquired hypertrophy of the pyloric muscle in infants occurring before 12 months of age and requiring pyloromyotomy. Newborns in whom pyloric stenosis was diagnosed prenatally or present at birth were excluded because of a presumed different cause. Redo pyloromyotomies were excluded. The control group consisted of all live births without IHPS in the two regions within the study period.
Data sources In North-Holland the hospital surgical databases of the two academic hospitals and of the single large regional hospital were systematically searched for patients born within the study period who underwent a pyloromyotomy for IHPS (either by laparoscopy or laparotomy). Detailed patient characteristics were obtained from the hospital information systems using a standardized form. Eurocat Northern Netherlands is a population-based birth defect registry covering the three Northern provinces since 1981.22 Children and fetuses with anomalies diagnosed before or after birth are eligible for registration at the Eurocat Northern Netherlands registry, if the mother lived in the region at the time of birth and the child has not reached the age of 16 at notification. There is no lower limit for gestational age, spontaneous and induced
82 Seasonal variations in IHPS incidence abortions are included. Notification of children and fetuses with congenital anomalies is voluntary. Registry personnel are actively involved in case ascertainment, using multiple sources such as obstetric records, hospital administration data, and pathology records. Parental informed consent is needed for registration. IHPS cases registered in one study region can not be registered as a case in the other region, and the regions are geographically separated by a large lake (Figure I). Information Chapter on the number of live births in the two regions within the various parts of the study period was obtained from Statistics Netherlands.21 Daily climatologic data throughout the whole study period were obtained from the regional weather observation stations (station numbers 240, 270, 278 and 280) of the 3 Royal Netherlands Meteorological Institute. 23
Data analysis Baseline characteristics of the two regions were described as percentages and means with standard deviations or medians with interquartile ranges. Prematurity was defined as a gestational age of less than 37 weeks. Ethnic origin was not registered in either region, remained unavailable for the Northern Netherlands and could only be assessed based on surname and given name of the infants. The incidence of IHPS per 1,000 live births was based on date of birth and was calculated by dividing the number of IHPS cases by the total number of live births within a region born within a certain year, half year, season or month, respectively. Mean overall incidence rates were calculated for each region and were reported with standard errors of the mean and 95% confidence intervals. The definition of seasons was based on a climate categorization of month of birth: winter (December, January and February), spring (March, April and May), summer (June, July and August) and autumn (September, October and November).23 Comparisons between and within the regions were performed by using independent t-tests for normally distributed continuous data and Mann-Whitney U tests for skewed continuous data. Chi square tests were applied for comparisons of proportions. The Walter and Elwood’s test for seasonality was performed to test for specific seasonal variations in IHPS incidence by month of birth within the two regions, adjusting for variation in the number of live births at risk. This seasonality test allows it to estimate a time at which a maximum (direction of maximum: θ max) occurs in a postulated simple harmonic fluctuation during a certain period while correcting for variations in the population at risk.24 To assess internal consistency of data, baseline characteristics and variations in incidence of IHPS were compared between patients recruited from the two different academic centers in North-Holland (n=332 and n=216, respectively). This was not done for the single regional hospital in North-Holland as numbers were too small. For the Northern-Netherlands, no data were available to test for internal consistency in a similar way.
83 chapter 3
Mean monthly values for four different climate indices were calculated from daily values of the regional weather observation stations. In the Northern Netherlands, the mean values of the three regional weather observation stations (station numbers 270, 280 and 289) were calculated into a mean value of the region. Climate indices comprised air pressure, absolute temperature, humidex and wind chill equivalent temperature. Air pressure was defined as mean sea level air pressure in 0.1 hPa. Absolute temperature was measured in degrees Celsius. Humidex is a measure for the temperature adjusted for humidity and was calculated according to the humidex formula by Masterton and Richardson.25 Thermal strain in the cold is a combination of ambient temperature and wind speed, expressed in the wind chill equivalent temperature (WCET). WCET was calculated according to the wind chill formula of the National Weather Service.26;27 After ruling out non-linear association by scatter plotting, Spearman’s rank correlation coefficient was used to assess linear correlation between the separate mean absolute climate indices and the incidence of IHPS in both regions according to month and season of birth. The statistical program R version 2.14.1 (R Foundation for Statistical Computing, Vienna, Austria) was used for Walter and Elwood’s test. All other statistics were performed using the Statistical Package for Social Sciences (SPSS) version 16.0 (SPSS Inc., Chicago, IL). A p-value of <0.05 was considered statistically significant.
Results Baseline characteristics Between 1995 and 2009, 475,941 children were born in North-Holland, of which 612 developed IHPS. In the Northern Netherlands, 287,207 children were born in this period, of which 355 infants were registered with IHPS. Baseline characteristics of the two studied populations are displayed in Table I. Male predominance in both regions was comparable to ratios previously published in literature. The proportion of prematurely born IHPS patients was significantly higher in North-Holland (15.0%) compared to the Northern Netherlands (7.1%), also showing in significant differences in overall birth weight and age at pyloromyotomy between the two populations if not corrected for the prematurity. In both cohorts, the median age at pyloromyotomy was higher in prematurely born infants than in term infants. Term infants were significantly older at surgery in North-Holland than in the Northern Netherlands. When age at pyloromyotomy of preterm infants was corrected for gestational age, no significant differences in median age at surgical procedure remained between the two study groups. Comparison of baseline characteristics between patients recruited from the two different academic centers in North-Holland did not result in any significant difference (data not shown).
84 Seasonal variations in IHPS incidence
Table I | Baseline characteristics of all IHPS patients born in the two study regions between 1995 and 2009 North-Holland Northern Netherlands p-value Total population 2,600,000 1,700,000 Total immigration rate 9.8/1,000 5.9/1,000 Total number of live births 475,941 287,207 Total percentage prematurely born live births 7.0% 7.7% (gestational age <37 wks) Chapter Number of IHPS cases 612 355 Incidence IHPS / 1,000 live births 1.29 1.24 ns % males 86.3% 85.6% ns Non-Western origin 13% n/a 3 Median gestational age (days) 280 (266-280) n=546 278 (268-285) n=312 ns Number preterms (gestational age <37 wks) (%) 82/546 (15.0 %) 22/312 (7.1%) .001 Mean weight at birth (grams) all 3321 (± 682) n=502 3448 (± 591) n=313 .005 preterms (<37 wks) 2310 (± 499) n=76 2506 (± 424) n=22 ns terms (≥ 37 wks; <42wks) 3492 (± 541) n=426 3530 (± 533) n=286 ns Median age at pyloromyotomy (days) all 32 (25-45) n=612 30 (21-40) n=183 .002 preterms (<37 wks) 40 (31-55) n=82 40 (25-68) n=8 ns terms (≥ 37 wks; <42wks) 33 (25-41)n=464 30 (21-39) n=159 .03 terms + preterms corrected for gestational age to term 29 (21-39) n=546 29 (19-39) n=167 ns IHPS = infantile hypertrophic pyloric stenosis; ns = non significant; n/a = not available. Median values include interquartile ranges in brackets; mean values include standard deviations in brackets
Overall incidence of IHPS The mean overall incidence of IHPS by year of birth was not significantly different between the two study regions: in North-Holland the mean incidence was 1.29 (SE .06, 95% CI 1.16 – 1.42) per 1,000 live births and in the Northern Netherlands it was 1.24 (SE .07, 95% CI 1.09 – 1.39) per 1,000 live births (p = .62). During the whole study period, fluctuation was seen in the yearly incidence of IHPS within the two regions without a significant difference in incidence between the years (North-Holland X2 19.5, p = .146; Northern Netherlands X213.9, p = .457). The highest yearly incidence was found in children born in the year 2000 (1.67/1,000 live births) in North-Holland and in children born in 2008 (1.57/1,000 live births) in the Northern Netherlands (Fig. II).
Monthly and seasonal variations The highest overall monthly incidence of IHPS was found in children born in December in North-Holland (Fig. III), and in the Northern Netherlands in children born in November.
85 chapter 3
2.0 Figure II | Yearly incidence of IHPS by year of birth per 1,000 live births between 1995 and 2009 in the two study regions 1.5
1.0
0.5 North-Holland Northern Netherlands Incidence IHPS per 1,000 livebirths 0.0
1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 Year of birth
2.0 North-Holland 2.0 Northern Netherlands
1.5 1.5
1.0 1.0
0.5 0.5
0.0 0.0 1 2 3 4 5 6 7 8 9 10 11 12 1 2 3 4 5 6 7 8 9 10 11 12 IHPS incidence per 1,000 livebirths Month of birth IHPS incidence per 1,000 livebirths Month of birth
Figure III | Incidence of IHPS per 1,000 live births by month of birth between 1995 and 2009 in the two study regions
2.0 North-Holland 2.0 Northern Netherlands
1.5 1.5
1.0 1.0
0.5 0.5
0.0 0.0 winter spring summer autumn winter spring summer autumn IHPS incidence per 1,000 livebirths Season of birth IHPS incidence per 1,000 livebirths Season of birth Figure IV | Incidence of IHPS per 1,000 live births by season of birth between 1995 and 2009 in the two study regions
The Walter and Elwood’s test showed a significant seasonal variation in IHPS occurrence by month of birth in North-Holland with a peak in December (test-value =10.5, θ max= 5.58, p=.005). No similar seasonality in IHPS incidence was present in the Northern Netherlands. Children born during the winter season in North-Holland showed the highest IHPS incidence rate (1.52/1,000 live births) and in the Northern Netherlands the highest incidence rates was in children born in autumn (1.42/1,000 live births) (Fig. IV). A statistically significant difference between the seasons was present in North-Holland (X2 6.29, p=.012): the IHPS
86 Seasonal variations in IHPS incidence incidence in winter was higher compared to summer and spring (X2 6.29, p=.012 and X2 7.11, p=.008, respectively). Redoing these analyses separately for the two academic centers in North-Holland yielded the same results (data not shown). In the Northern Netherlands, no significant differences between the seasons were observed.
Association with climate indices Chapter Correlation analysis with climate indices did yield a significant, but weak negative correlation between IHPS incidence by month of birth and mean values of absolute temperature (r = -.20, p=.006), humidex (r = -.20, p=.004) and wind chill equivalent temperature (r = -.21, p=.006) in North-Holland. No such correlations were significant in the Northern 3 Netherlands.
Discussion We report here on the results of an epidemiological study on the incidence of IHPS in two closely located regions in The Netherlands. Due to the location of North-Holland and Northern Netherlands within the Netherlands, separated by a lake (Fig. I), there is no overlap in care to IHPS children in the two regions, despite their close proximity. We found a significant seasonal influence on IHPS incidence in the region North-Holland but not in the region Northern Netherlands. In addition, the seasonal variation in IHPS incidence showed only a weakly negative correlation with several local climate factors such as absolute temperature, humidex and wind child equivalent temperature for North-Holland. It is unlikely that the observed difference in incidence of IHPS in the various parts of the year in one of the regions has been caused by the climate itself since the climatic differences between the study regions are small, and due to careful and continuous determinations of local climate these small differences could be further corrected for. The significant peak incidence of IHPS found in children born during the winter months in one of the regions is most in line with the results of a previous study from Belfast investigating seasonal variation in IHPS.7 Other studies described peak incidences in other parts of the year6;8 -11, or could not demonstrate seasonal variation in the incidence of IHPS at all.12-20 The results of previously conducted studies are summarized in Table II. The current study suggests a role for local environmental influences other than climate changes which are still season specific. These factors may have acted anywhere between the moment of conception and early postnatal life. It may be either completely environmentally determined factors, or environmentally determined factors that act mainly in the presence of a particular genetic constitution. The difference in percentages of immigrants between the two regions may be a factor of influence here, as this indicates a significant difference in genetic constitution between the two regions. In this study, at least 13% of all IHPS patients from North-Holland were children of immigrants. Furthermore,
87 chapter 3
Table II | Overview of Studies on Seasonal Variations in the Incidence of IHPS Study Region Population Definition seasons Incidence based on Seasonal Results variation Kwok et al. 19676 USA 248 months of the year, no definition seasons Date of admission + peak in Spring and Autumn Dougall 196912 Scotland 200 months of the year (no seasons) Date of surgery - - Campbell 196913 Hawaii 275 months of the year (no seasons) Date of birth - - Dodge 19757 Northern-Ireland 521 Winter: Nov-April Date of birth + peak in Winter Adelstein et al. 19768 United Kingdom 220 months and quarters of the year Date of birth + peak in July Kerr 198034 Scotland 31 months of the year (no seasons) Date of birth ? numbers too small to draw conclusions Walpole 198114 Canada 715 months, quarters, half years Date of birth - - Walsworth-Bell 19839 United Kingdom 687 months of the year (no seasons) Date of birth + peak in September and October Webb et al. 198310 Wales 115 months of the year (no seasons) Date of birth + peak in April, low in October Habbick et al. 198915 Canada 813 months of the year (no seasons) Date of discharge - - Rasmussen et al. 198916 Denmark 679 no definition seasons Date of onset symptoms - - Schechter et al. 199717 USA 1963 months of the year (no seasons) Date of birth - peak in July, low in November Sule et al. 200135 Scotland 230 months of the year (no seasons) Date of birth - - Safford et al. 200518 USA 11003 no definition seasons Date of admission - - Tiao et al. 201119 Taiwan 962 Winter: dec - feb; Date of birth - - Spring: mar - may; Summer: jun - aug; Autumn: sep - nov Leong et al. 2011 20 Taiwan 1077 Winter: nov- jan; Date of admission + - - Spring: feb - apr; Date of birth Summer: may - jul; Autumn: aug - oct Zamakhshary et al. 201111 Canada 1777 Winter: dec - feb; Date of surgery + peak in Summer, low in Winter Spring: mar - may; Summer: jun - aug; Autumn: sep - nov one may hypothesize that maternal nutrition patterns or medication use because of viral and subsequent bacterial infections varying along the seasons have been such an influence on the development and functioning of the pylorus of the child. This may act either directly or through a change in gene expression by an altered methylation status. Imprinting disturbances are increasingly recognized as having a vast influence on health, not only directly but also by passing the altered imprinting from generation to generation.28
The proportion of prematurely born children with IHPS in North-Holland was more than twice the proportion of prematurely born infants with IHPS in the Northern Netherlands. An explanation might have been the high percentage of immigrants living in North-Holland: studies conducted in the Netherlands have shown that children born to mothers of Non-Western origin are more likely to be born prematurely.29;30 However, between 2002 and 2009, the percentage of premature live births in general was found to be remarkably lower in the province of North-Holland (7.0%) than in the Northern Netherlands (7.7%)
88 Seasonal variations in IHPS incidence
Table II | Overview of Studies on Seasonal Variations in the Incidence of IHPS Study Region Population Definition seasons Incidence based on Seasonal Results variation Kwok et al. 19676 USA 248 months of the year, no definition seasons Date of admission + peak in Spring and Autumn Dougall 196912 Scotland 200 months of the year (no seasons) Date of surgery - - Campbell 196913 Hawaii 275 months of the year (no seasons) Date of birth - - Dodge 19757 Northern-Ireland 521 Winter: Nov-April Date of birth + peak in Winter Chapter Adelstein et al. 19768 United Kingdom 220 months and quarters of the year Date of birth + peak in July Kerr 198034 Scotland 31 months of the year (no seasons) Date of birth ? numbers too small to draw conclusions Walpole 198114 Canada 715 months, quarters, half years Date of birth - - Walsworth-Bell 19839 United Kingdom 687 months of the year (no seasons) Date of birth + peak in September and October 3 Webb et al. 198310 Wales 115 months of the year (no seasons) Date of birth + peak in April, low in October Habbick et al. 198915 Canada 813 months of the year (no seasons) Date of discharge - - Rasmussen et al. 198916 Denmark 679 no definition seasons Date of onset symptoms - - Schechter et al. 199717 USA 1963 months of the year (no seasons) Date of birth - peak in July, low in November Sule et al. 200135 Scotland 230 months of the year (no seasons) Date of birth - - Safford et al. 200518 USA 11003 no definition seasons Date of admission - - Tiao et al. 201119 Taiwan 962 Winter: dec - feb; Date of birth - - Spring: mar - may; Summer: jun - aug; Autumn: sep - nov Leong et al. 2011 20 Taiwan 1077 Winter: nov- jan; Date of admission + - - Spring: feb - apr; Date of birth Summer: may - jul; Autumn: aug - oct Zamakhshary et al. 201111 Canada 1777 Winter: dec - feb; Date of surgery + peak in Summer, low in Winter Spring: mar - may; Summer: jun - aug; Autumn: sep - nov
and the rest of the country (7.3%).31 Earlier studies from other countries reported normal to lower rates of prematurity in IHPS patients and therefore, the high percentage of preterm born IHPS children in the province of North-Holland remains remarkable and deserves further investigation. In neither of the two study regions we found a change in incidence of IHPS over time. In some Northern European countries, a decline in IHPS incidence over the last years has been reported. 32 Since parents are encouraged to put babies in a supine sleeping position, a comparable decline in the incidence of Sudden Infant Death Syndrome has been observed and it has therefore been suggested that IHPS is related to a prone sleeping position.32 This suggested decline in IHPS incidence could not be confirmed in the present study. The strength of the present study is the large sample sizes of the two studied populations, the relatively long study period, the correction for fluctuations in total number of live births, and the correlation with reliably ascertained local climate data. The ascertainment of IHPS patients in the regions has been very high, confirmed by incidence data in the
89 chapter 3 present study regions that are similar to those in earlier studies. For one of the regions (North-Holland) data were gathered separately from the two large academic hospitals and each set of data showed the same results confirming the reliability of the data. In the near future it will be possible to compare the genetic variation within the various parts of the Netherlands with the results of the Dutch project “Genome of the Netherlands”. In this project, the genome of large groups of trios (child and both parents) from all regions of the Netherlands has been sequenced and will be made available for research purposes.33 We have initiated molecular genetic studies which will also include the study of the methylation of the complete genome (“methylome”) as such methylation change might account for an environmental influence acting through a changed genetic information. These studies and results of studies similar to the study reported here, should shed further light on the etiology of IHPS. We conclude that there is a remarkable and significant difference in occurrence of IHPS in the various parts of the year in one of the studied populations, in contrast to another closely located independent study population. Climate changes seem unlikely to be the explanation, but there may be other season specific influences such as feeding habits or medication use that have a significant influence. These environmental influences may act independently of or in concert with the genetic make-up of the population, and may also act through changes in imprinting status of genes important for the development of IHPS.
Acknowledgements The authors would like to thank N. van Geloven, MsC of the Department of Epidemiology and Biostatistics of the Academic Medical Center of Amsterdam for statistical help, J. Salman, MD, medical student, for assisting in the data collection, and R. Sluijter of the Royal Netherlands Meteorological Institute (KNMI) for climate information.
90 Seasonal variations in IHPS incidence
Reference List
(1) Wyllie R. Pyloric stenosis and congenital anomalies of the stomach. In: Kliegman RM, Behrman RE, Jenson HB, Stanton BF, eds. Nelson Textbook of Pediatrics. 18th ed. Philadelphia: Saunders Elsevier; 2007. (2) Applegate MS, Druschel CM. The epidemiology of infantile hypertrophic pyloric stenosis in New York State, 1983 to 1990. Arch Pediatr Adolesc Med 1995;149:1123-1129.
(3) MacMahon B. The continuing enigma of pyloric stenosis of infancy: a review. Epidemiology 2006;17:195- Chapter 201. (4) Ranells JD, Carver JD, Kirby RS. Infantile hypertrophic pyloric stenosis: epidemiology, genetics, and clinical update. Adv Pediatr 2011;58:195-206. (5) Peeters B, Benninga MA, Hennekam RC. Infantile hypertrophic pyloric stenosis-genetics and syndromes. Nat Rev Gastroenterol Hepatol 2012. 3 (6) Kwok RH, Avery G. Seasonal variation of congenital hypertrophic pyloric stenosis. J Pediatr 1967;70:963- 965. (7) Dodge JA. Infantile hypertrophic pyloric stenosis in Belfast, 1957-1969. Arch Dis Child 1975;50:171-178. (8) Adelstein P, Fedrick J. Pyloric stenosis in the Oxford Record Linkage Study area. J Med Genet 1976;13:439- 448. (9) Walsworth-Bell JP. Infantile hypertrophic pyloric stenosis in Greater Manchester. J Epidemiol Community Health 1983;37:149-152. (10) Webb AR, Lari J, Dodge JA. Infantile hypertrophic pyloric stenosis in South Glamorgan 1970-9. Effects of changes in feeding practice. Arch Dis Child 1983;58:586-590. (11) Zamakhshary MF, Dutta S, To T, Stephens D, Langer JC, Wales PW. Seasonal variation of hypertrophic pyloric stenosis: a population-based study. Pediatr Surg Int 2011;27:689-693. (12) Dougall AJ. Infantile pyloric stenosis. A review of 200 cases. Scott Med J 1969;14:156-161. (13) Campbell MA. The question of seasonal variation of pyloric stenosis. J Pediatr 1969;74:1006-1007. (14) Walpole IR. Some epidemiological aspects of pyloric stenosis in British Columbia. Am J Med Genet 1981;10:237-244. (15) Habbick BF, To T. Incidence of infantile hypertrophic pyloric stenosis in Saskatchewan, 1970-85. CMAJ 1989;140:395-398. (16) Rasmussen L, Green A, Hansen LP. The epidemiology of infantile hypertrophic pyloric stenosis in a Danish population, 1950-84. Int J Epidemiol 1989;18:413-417. (17) Schechter R, Torfs CP, Bateson TF. The epidemiology of infantile hypertrophic pyloric stenosis. Paediatr Perinat Epidemiol 1997;11:407-427. (18) Safford SD, Pietrobon R, Safford KM, Martins H, Skinner MA, Rice HE. A study of 11,003 patients with hypertrophic pyloric stenosis and the association between surgeon and hospital volume and outcomes. J Pediatr Surg 2005;40:967-972. (19) Tiao MM, Tsai SS, Kuo HW, Yang CY. Epidemiological features of infantile hypertrophic pyloric stenosis in Taiwan: a national study 1996-2004. J Gastroenterol Hepatol 2011;26:78-81. (20) Leong MM, Chen SC, Hsieh CS et al. Epidemiological features of infantile hypertrophic pyloric stenosis in Taiwanese children: a Nation-Wide Analysis of Cases during 1997-2007. PLoS One 2011;6:e19404. (21) CBS Statline (database). http://statline.cbs.nl . 2012. Voorburg, The Netherlands, Statistics Netherlands. (22) Greenlees R, Neville A, Addor MC et al. Paper 6: EUROCAT member registries: organization and activities. Birth Defects Res A Clin Mol Teratol 2011;91 Suppl 1:S51-S100.
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(23) Royal Netherlands Meteorological Institute (KNMI). http://www.knmi.nl . 2012. De Bilt, The Netherlands, KNMI. (24) Walter SD, Elwood JM. A test for seasonality of events with a variable population at risk. Br J Prev Soc Med 1975;29:18-21. (25) Masterton JM, Richardson FA. Humidex: A Method of Quantifying Human Discomfort due to Excessive Heat and Humidity. Ontario, Canada: Environment Canada, Atmospheric Environment Service, 1979. (26) National Weather Service. http://www.weather.gov/om/windchill . 2001. Silver Spring, USA. (27) ISO-11079. Ergonomics of the thermal environment - Determination and interpretation of cold stress when using required clothing insulation (IREQ) and local cooling effects. Geneva, Switzerland: 2007. (28) Kaati G, Bygren LO, Edvinsson S. Cardiovascular and diabetes mortality determined by nutrition during parents’ and grandparents’ slow growth period. Eur J Hum Genet 2002;10:682-688. (29) Goedhart G, van EM, van der Wal MF, Bonsel GJ. Ethnic differences in preterm birth and its subtypes: the effect of a cumulative risk profile. BJOG 2008;115:710-719. (30) Ravelli AC, Tromp M, van HM et al. Decreasing perinatal mortality in The Netherlands, 2000-2006: a record linkage study. J Epidemiol Community Health 2009;63:761-765. (31) The Netherlands Perinatal Registry. 2012. (32) Nielsen JP, Haahr P, Haahr J. Infantile hypertrophic pyloric stenosis. Decreasing incidence. Dan Med Bull 2000;47:223-225. (33) Genome of the Netherlands (GoNL). http://www.nlgenome.com . 2012. (34) Kerr AM. Unprecedented rise in incidence of infantile hypertrophic pyloric stenosis. Br Med J 1980;281:714- 715. (35) Sule ST, Stone DH, Gilmour H. The epidemiology of infantile hypertrophic pyloric stenosis in Greater Glasgow area, 1980-96. Paediatr Perinat Epidemiol 2001;15:379-380.
92 Part III
Functional defecation disorders
Chapter 4
Childhood constipation; an overview of genetic studies and associated syndromes
Babette Peeters, Marc A. Benninga, Raoul C. Hennekam
Best Pract. Res. Clin. Gastroenterol. 2011; 25(1):73-88 chapter 4
Abstract Constipation is a common problem in children but little is known about its exact pathophysiology. Environmental, behavioural but also genetic factors are thought to play a role in the aetiology of childhood constipation. We provide an overview of genetic studies performed in constipation. Until now, linkage studies, association studies and direct gene sequencing have failed to identify mutations in specific genes associated with constipation. We show that along with functional constipation, there are numerous clinical syndromes associated with childhood constipation. These syndromic forms of constipation appear to be the result of mutations in genes affecting all aspects of the normal physiology of human defecation. We stress that syndromic causes of childhood constipation should be considered in the evaluation of a constipated child.
96 Genetics of childhood constipation
Introduction Constipation can be characterized by infrequent and/or difficult stool passage.1 It occurs frequently within the general population. In children, the reported prevalence of constipation ranges from 0.7% to 29.6% (median 8%), and most epidemiological studies show no differences in prevalence of constipation between boys and girls, in contrast to adult literature where a higher prevalence in women is suggested.2,3 However, evidence of gender differences is inconsistent. The wide variance in reported prevalence rates and inconsistent evidence of gender differences is at least in part the result of the variations in definitions of constipation used in the various studies. In a fraction of patients, constipation is secondary to a known pathology such as anorectal Chapter malformations, Hirschsprung disease, neurological abnormalities or a metabolic disorder.4 In the majority of patients however, the aetiology remains unknown and a diagnosis of functional constipation is made. The diagnostic criteria for functional constipation as worded in the ROME III criteria for paediatric functional gastrointestinal disorders are 4 the presence of at least two of the following for at least two months: 1) two or fewer defecations per week; 2) at least one episode of faecal incontinence per week; 3) retentive posturing or stool retention; 4) painful or hard bowel movements; 5) presence of a large faecal mass in the rectum; 6) large diameter stools which may obstruct the toilet in the absence of structural or metabolic aetiologies.5 In recent years, research in aetiology and pathogenesis of childhood constipation has focused on environmental factors, behavioural problems, and genetic factors. Environmental factors associated with a higher prevalence of childhood constipation are varied and include factors such as diet and mobility of the child, but also low maternal educational level, or social circumstances. 6 The relation with behavioural problems is similarly complex, in part because constipation can be both a cause and product of behavioural problems. 7 Furthermore, constipation has been reported more frequently in children with specific behavioural phenotypes such as autism spectrum disorder.8,9 The role of genetics in the aetiology of constipation is still largely unknown. A limited number of studies have been published on the occurrence of constipation among family members of patients with constipation.10-12 Constipation occurred more frequently in family members of patients with childhood constipation than in family members of controls (see below). Childhood constipation has been described frequently in patients with hereditary syndromes (Table I). This may indicate a substantial influence of genetic factors in the aetiology of childhood constipation, either as Mendelian disorder or in a polygenic or multifactorial way. Here, we review the literature on the genetics of childhood constipation and associated clinical syndromes, to offer insight into the clinical and molecular pathogenesis of constipation. We do not discuss in detail the syndromes and genes associated with Hirschsprung disease as this has been reviewed in detail recently.13
97 chapter 4
Familial aggregation studies In many common disorders identifying familial aggregation, or clustering is often a first step in genetic research and provides grounds for further genetic analyses.14 In constipation only limited studies have been performed. In 2007, Chan et al. published the results of a study conducted in a tertiary referral centre in China in which adult patients with and without chronic constipation according to the ROME II criteria were asked to recruit first-degree relatives and their spouses for a questionnaire study.11 From 132 index patients and 114 controls, they interviewed a total of 1268 family members, and found the prevalence of constipation among probands’ relatives to be 16.4%, vs. 9.1% in controls’ relatives. A family history of constipation was associated with an increased risk, with odds ratios of 2.02 when at least one relative was affected, and 3.99 when at least two relatives were affected. In a subsequent study, the authors found several clinical characteristics were associated with a positive family history, such as a younger age of onset, longer duration of complaints, and complications including haemorrhoids, anal fissures and rectal prolapse.15 Although these data suggest that a positive family history has an influence on the clinical course of constipation, a recent review by Pijpers et al. reported that in childhood constipation, a positive family history is not associated with eventual recovery rates.16 A comparable study in family members of children with functional constipation according to the ROME III criteria studied 310 first-degree family members in probands and controls by a questionnaire study.10 Siblings or parents of probands had a significantly higher rate of constipation compared to first-degree family members of the control group (30% vs. 7% for siblings and 42% vs. 9% for parents, respectively). It was not reported whether there were also family members with constipation in childhood. Another familial aggregation study investigated the prevalence of functional gastrointestinal disorders in parents and siblings of children affected by a functional gastrointestinal disorder.12 In 41% of mothers of constipated children, constipation was found too, and this percentage possibly differed from mothers of healthy controls (9.2%; no p-value reported). In fathers and siblings, no statistically significant difference was found between family members of children with functional gastrointestinal disorders and controls. The authors concluded that their study reaffirmed the hypothesis that functional gastrointestinal disorders have a strong genetic background and an affected mother indicates that her offspring is at higher risk for a functional gastrointestinal disorder.12 The aetiological factors of childhood and adult constipation may be different, however no large case-control studies have been conducted, looking at the incidence and prevalence in first-degree relatives (parents; sibs; offspring) of patients with childhood constipation specifically. If such a study would be compared to a similar study of adult-onset constipation, it would allow more firm conclusions to be drawn on any differences in their genetic aetiology. It would be important in such studies to exclude syndromic forms of constipation (see below).
98 Genetics of childhood constipation
Dermatoglyphics Fingerprint patterns or dermatoglyphics are specific line patterns on the palmar side of fingers and palms, which are considered unique (except in identical twins), and genetically determined.17,18 Several congenital conditions such as bèta-thalassemia major and PHOX2B-confirmed congenital central hypoventilation syndrome have been associated with specific fingerprint patterns.19,20 Some studies have suggested that the prevalence of simple arches on the tips of the fingers is increased in childhood constipation.21,22 Gottlieb et al. studied the fingerprints of 155 children with early onset constipation (before 10 years of age), children with later onset constipation and healthy controls attending a gastrointestinal clinic.21 In these individuals, they found prevalence rates of simple arches of 53%, 13% and 11%, respectively. The high percentages found might partly be a result of Chapter a selection bias, as the recruitment site of the total study population was a gastrointestinal clinic. Comparable results were reported by Staiano et al. who found small arches on the tops of the fingers in 38% of constipated children compared to 11% of healthy subjects.22 Study numbers were small. In 2003, Jackson et al. compared the fingerprints of 30 children 4 with refractory constipation needing surgery (mean age of onset 2.65 years) and their first-degree relatives to those in controls and their relatives.23 They found that the number of simple arch patterns occurred in a similar frequency in severely constipated children and control children (13% vs. 7%) and their families (16% vs. 13%). Unfortunately, further statistical analysis of the figures was not provided. The numbers in this study were small and did not allow firm conclusions. A case-control study in a much larger group and with adequate statistical analysis is needed to evaluate this properly.
Association studies We performed a literature search in PubMed using as search (MeSH) terms “Constipation” combined with either “Linkage (Genetics)”; “Genome wide association study”; “Genetic association studies”; and “Genes”. Reference lists of papers retrieved in this way were hand searched for other relevant publications. Only one study investigated a series of candidate genes in families of patients with childhood constipation.24 In 2007, Garcia-Barceló et al. studied 35 families with children (67% male; age 5.5 – 19.7 years [mean 11.5]) with constipation as defined by the ROME II criteria. All probands had slow colonic transit times on scintigraphy. Thirteen probands had one or more affected family members. Unfortunately, more detailed information about the families and their members was not provided. In the probands and their parents, genes encoding for gut neurotransmitters (TAC1, TAC3, VIP), genes encoding for their receptors (TACR1, TACR2, TACR3), and the KIT and NOS1 genes were evaluated by investigating 117 single nucleotide polymorphisms (SNPs) distributed among these genes. Results were compared with HapMap data based on the analysis of 30 trios (parents and child) of European descent. Five SNPs showed an association with slow transit constipation
99 chapter 4 in children, located in TACR1, TACR3 (twice), KIT and NOS1 genes. No replication study has been performed. The study population was rather small and the number of genes studied limited. It is not clear whether within their study group there were one or more larger families, which would have allowed separate linkage analysis. It can be expected that linkage studies in single large, well-studied families in which constipation segregates will yield more information on genes possibly involved in constipation. Studies of small and homogeneous groups of patients with distinct constipation phenotypes using next generation sequencing techniques such as total exome sequencing, may identify novel genes associated with such extreme or specific phenotypes. Understanding the function of such genes will yield important information with respect to both the aetiology and pathogenesis of constipation. Direct sequencing of candidate genes in adults with functional constipation has been performed in several studies. Knowles et al. studied 16 patients with confirmed idiopathic slow transit constipation with and without a family history of Hirschsprung disease.25 Patients were screened for germline mutations in the RET proto-oncogene and GDNF (encoding for one of RET’s ligands), two genes known to be associated with Hirschsprung disease.13 In this small group of patients with idiopathic slow transit constipation, no germline mutations or rare polymorphisms in GDNF or RET were found. In 2002 Chen et al. performed a study in 26 adults with slow transit constipation in which they screened for mutations in NRTN (neurturin), a gene encoding for a ligand which like GDNF signals through the RET tyrosine-kinase complex.26 NRTN was considered a candidate gene due to a previous study reporting NRTN-deficient mice to show a reduced enteric plexus innervation density, reduced gastrointestinal motility and autonomic defects.27 Fifteen of the 26 study patients had a positive family history of constipation and two patients had a family member with Hirschsprung disease. They could not demonstrate germline mutations or rare polymorphisms of NRTN in any patient studied. In 23 adults with slow transit constipation, analysis of the proto-oncogene C-kit, suggested to play a crucial role in the development of interstitial cells of Cajal and intestinal pacemaker activity, yielded no evidence for an association between mutations in C-kit and slow transit constipation.28 Eight of the included patients suffered from non-obstructive carcinoma or adenoma. In 2007, Rossi et al. searched for chromosomal abnormalities in colonic biopsies of 22 adults with intractable constipation requiring surgery. Fluorescence in situ hybridization (FISH) was used to study abnormalities in chromosomes 1, 18, 17, X, and Y in enteric neurons and glial cells. In 45% of patients, they found only numerical abnormalities of chromosome 1 (aneusomy >10%), mainly in the enteric neurons. They concluded that it is possible that in at least a subgroup of patients with slow transit constipation a genetic basis for their complaint is present.29
100 Genetics of childhood constipation
Animal models Mouse models are abundant for Hirschsprung disease, but limited for functional constipation. We have been unable to find recent molecular genetic studies in animal models for functional constipation.
Syndromes associated with childhood constipation The number of syndromes associated with an increased frequency of childhood constipation is large. We performed a literature search in PubMed, OMIM (Online Mendelian Inheritance in Man) and LMD (London Medical Databases) using the following MeSH terms and text words: Constipation AND (Syndrome OR Disease OR Disorder OR Genes OR Genetic). Only papers concerning constipation in childhood were considered Chapter eligible for this review. Reference lists of papers retrieved in this way were hand searched for other relevant publications. Syndromes identified in this way varied in prevalence from very rare to relatively common. 4 The prevalence of childhood-onset constipation in each syndrome was equally variable. As estimates of the prevalence of this feature in any syndrome may be affected by ascertainment bias, we have included all syndromes where childhood constipation has been reported. We categorized all syndromes according to the (presumed) pathogenesis of constipation (Table 1). If more than one pathogenesis might play a role in constipation we included the entity only once, under the category that was assumed to play the most significant role. In the text we only discuss a single syndrome of each subcategory in detail to illustrate the presumed pathogenesis of constipation. Normal defecation is complex, it involves the rapid semi-voluntary emptying of the rectum and a variable part of the colon and it requires a high degree of coordination to achieve evacuation. Smooth and striated muscle and the central, somatic, autonomic and enteric nervous systems are all involved. In constipation, one or more of the above mentioned factors is usually affected as can be seen in the disorders described below.30
Autonomic nervous system Hereditary sensory and autonomic neuropathy type 3 A balanced tuning between the muscular apparatus of the gut and a coordinated and programmed neural control is essential for normal gastrointestinal motility. The enteric nervous system (ENS) provides direct intrinsic neuronal control of intestinal motility and via activation by enteric sensory- and interneurons it gives rise to local reflex activity. The ENS in turn is modulated through the sympathetic, parasympathetic and extrinsic afferent pathways.30 Sympathetic pathways moderate blood flow in the gut through vasoconstriction, modulate secretory activity and temper enteric motor reflexes and the sacral parasympathetic pathways carry out an opposite effect.
101 chapter 4
In hereditary sensory and autonomic neuropathy type 3 (HSAN III, OMIM 22390), also referred to as Riley-Day syndrome or familial dysautonomia, the balance needed for normal gastrointestinal motility is disturbed by autonomic dysfunctioning. HSAN III is an autosomal recessive inherited disorder associated with a wide spread sensory and autonomic dysfunction. The congenital disorder has an incidence of one per 3600 live births and is almost exclusive to individuals of Eastern European Jewish extraction. Manifestations of dysautonomia are present in vasomotor regulation, temperature stability, pain perception, muscle tone regulation, lacrimation, and many other functions. Abnormal gastrointestinal motility manifesting as cyclic vomiting and childhood constipation is a frequent characteristic.31 HSAN III is caused by a mutation in IKBKAP, encoding for a protein involved in regulation of polarized exocytosis of neuronal cells. Exocytosis is a cellular process by which cells excrete waste products or chemical transmitters and disruption of this process is the likely pathogenic mechanism.32
Innervation Ochoa syndrome If the local gut innervation is disturbed, direct signals from the ENS and indirect signals from the sympathetic and parasympathetic nervous system are affected resulting in disturbed gut motility. Ochoa syndrome can serve as an example of a disorder due to such disturbed innervation. Ochoa syndrome, also known as urofacial syndrome, is an autosomal recessive congenital disorder mainly characterized by facial and urological manifestations. Patients show an odd grimacing facial expression when smiling. They have dysfunctional motility of the ureters, leading to extreme hydroureters and secondary voiding problems, infections and renal damage. In two-third of patients, constipation is found, ascribed to neurogenic alterations.33 Mutations in HPSE2 have been found to be associated with Ochoa syndrome. HPSE2 (heparanase) has been suggested to regulate peripheral innervation and coordination of muscles, but its exact biological function has not yet been characterized.34
Muscular Spinal Muscular Atrophy Smooth muscle cells and interstitial cells of Cajal play a major role in normal gastrointestinal motility.30 These cells propagate rhythmic contractions of the colonic wall and propulsion of content throughout the gut. Next to the intrinsic muscles of colon and rectum, muscles of the abdominal wall assist with defecation by increasing the intra-abdominal and intra-rectal pressure. In patients with Spinal Muscular Atrophy (SMA), proximal muscle weakness is a cardinal feature due to degeneration of motor neurons of the spinal cord and cranial motor nuclei. The disorder is caused by a mutation in SNM1 (survival motor neuron 1). SMN1, together
102 Genetics of childhood constipation with SMN2, encodes for the SMN protein, which has both neuronal- and muscle specific functions. Mutations in SMN1 may lead to motorneuron degeneration and associated denervation atrophy of skeletal muscles. In the spinal cords and muscles of SMA patients, low levels of SMN have been found, consistent with the clinical features of these patients.35 In most patients with SMA, constipation is a problem, commonly attributed to poor tone of abdominal muscles.36 However, a study investigating the myenteric plexus in the intestines of patients with SMA type 1 suggested not only poor abdominal muscle tone but also that disturbed intrinsic innervation of gut muscles may play a role in the pathophysiology of constipation in this disorder.37
Metabolic Chapter Fabry disease The exact pathogenetic mechanism behind the clinical manifestations of many metabolic disorders is not yet completely understood. In storage disorders such as Fabry (or Anderson-Fabry) disease the manifestations can be (in)directly explained by accumulation 4 of storage materials. Fabry disease is a congenital X-linked deficiency of the lysosomal enzyme α-galactosidase, caused by mutation in GLA and resulting in accumulation of glycosphingolipids.38 Glycosphingolipids mediate and modulate intercellular coordination and adhesion. Major features of Fabry disease are angiokeratomas of the skin, limb pain, progressive renal failure, cardiac defects and cerebrovascular accidents. Accumulation of glycosphingolipids occurs also in autonomic ganglia leading to autonomic dysfunction. This may cause constipation. Furthermore, there is evidence that accumulated glycosphingolipids in small mesenteric vessels may lead to microvascular ischemia of the gut. Hoffmann et al. studied gastrointestinal symptoms in Fabry disease patients and found a prevalence of constipation of 13.3% in children with the disease.39
Connective tissue Ehlers-Danlos syndrome type IV The wall of the gut needs a degree of firmness to allow stool propulsion. Furthermore, effective peristalsis is aided by attachment of the gut to other abdominal structures. Both aspects depend on the quality of the connective tissue. In addition, a weak abdominal wall can cause colonic protuberances which may lead to stasis of stools.40 Ehlers-Danlos syndrome (EDS) type IV, also described as the vascular type of EDS, is an inherited disorder of connective tissue. It is caused by heterozygous mutations in the COL3A1 gene, which codes for the protein Collagen type III that contributes to the organization of the extracellular matrix. The manifestations of the disorder are predominated by vascular problems, which include life-threatening rupture of great arteries. Joint hypermobility and skin manifestations are also present, and gastrointestinal complications are frequent.41 The main gastrointestinal manifestation is the development of a megacolon, perforations and
103 chapter 4 spontaneous rupture of the gut. About 25% of patients with EDS type IV have constipation. The symptoms of constipation usually begin in late childhood or adolescence.42
Coordination Posterior column ataxia with retinitis pigmentosa Normal defecation is complex and requires a high degree of coordination involving amongst other body positioning, respiration, and contractions and relaxations of various muscles groups including diaphragm, abdominal wall and the anal sphincter. Constipation is common in patients exhibiting impaired cognition, indicating that central nervous system function also plays an important role. In many mental retardation syndromes, additional factors such as impaired mobility and diet also contribute. In 1997, Higgins described an autosomal recessive form of ataxia starting in childhood which he named Posterior Column Ataxia with Retinitis Pigmentosa, after the main characteristics.43 The MRI of the spinal cord demonstrated hyper-intense signals in the posterior columns. The posterior column is responsible for transmitting sensory information from the body back to the cerebral cortex and therefore paramount in processing proprioception and coordination. Constipation was one of the resulting presentations.44
Water-electrolyte balance Gitelman syndrome In principle, constipation can arise in disorders affecting water-electrolyte balance for two reasons. Firstly, a reduction of the water content of the stools, either due to a disturbed water balance in the total body, or specifically in the stool due to abnormal electrolyte flow over the gut mucosa. Secondly as a result of muscle weakness of the abdominal wall and gut, due to electrolyte imbalance. Nephrogenic diabetes insipidus can serve as an example for disturbed water content of stools due to a total body water imbalance. Gitelman syndrome is a salt-losing tubulopathy characterized by hypokalemic alkalosis, hypomagnesaemia and hypocalciuria.45 The disease is caused by a mutation in SLC12A3 coding for the thiazide-sensitive NaCl co-transporter in tubular cells. Due to the ensuing electrolyte imbalances, clinical symptoms in Gitelman syndrome include muscle weakness, fatigue, polyuria, decreased physical growth and constipation, also in children. The NaCl co-transporter defect in Gitelman syndrome indicates a role of chloride in constipation but the exact pathogenesis is still largely unknown. A recent study (Bekkali et al., unpublished) showed that in gut biopsies also in children with severe functional constipation, disturbances in chloride secretion could be found. We have been unable to find studies investigating chloride channels in gut biopsies of Gitelman patients.
104 Genetics of childhood constipation
Malformation Currarino syndrome A physical obstruction caused by a congenital malformation can hinder adequate passage of stools and cause constipation. In addition, malformations affecting the sacral neural tissue often lead to constipation. Currarino syndrome may serve as an example. It is an autosomal dominant disorder characterized by a partial agenesis of the sacrum, anorectal malformations and presacral masses as the most prominent features. Lynch et al. reported a prevalence of 41% of constipation in 205 patients with Currarino syndrome.46 The bowel obstruction may be the result of the primary anorectal malformation, can be secondary to the presacral mass, or by spinal cord tethering due to the partial sacral agenesis. HLXB9 has been identified as the major causative gene in this disorder.47 HLBX9 is expressed Chapter in the sacral region during embryogenesis and is suggested to be involved in cellular migration and mesoderm formation in the caudal embryo.48
Chromosomal 4 Constipation is reported in patients with several chromosomal abnormalities (see Table 1). One explanation might be that some patients harbour a chromosomal deletion that includes deletion of genes that are required for normal defecation. Contiguous gene syndromes are characterized by multiple, apparently unrelated, clinical features caused by interstitial or terminal deletions of multiple adjacent genes within a chromosome.49 To our knowledge, no studies have investigated the regions of these known chromosomal anomalies to identify genes specifically associated with constipation. In order to visualize the information about chromosomal anomalies associated with constipation, an ideogram is provided in Figure 1.
Unknown The pathogenesis of constipation is unknown in several clinical syndromes (see Table 1). In many of these syndromes, associated genes are localized but their function in normal defecation is still unclear. As our knowledge of gene defects and gene functioning increases, our understanding of the pathophysiology of childhood constipation will improve.
Summary Constipation is common in children and can have a vast influence on physical and mental well-being. Many studies have been published on aetiology showing constipation to be extremely heterogeneous and although many mechanisms have been identified, still more are unclear. Genetic factors are known to play a role but linkage studies, association studies
105 chapter 4 and direct gene sequencing have yet to find mutations in genes specifically associated with constipation. This review stresses that along with functional constipation, syndromic forms of childhood constipation exist that should be considered when evaluating a constipated child. Mutations in genes affecting every body system required for normal defecation physiology are known, highlighting the complex pathogenesis of constipation. We are not aware of any studies that have investigated the prevalence of syndromic forms of constipation in children. In 1993, Loening-Baucke speculated that in over 90% of children with childhood constipation no etiological cause can be identified and the diagnosis of functional constipation should be made.50 According to the ROME III criteria, functional constipation can be diagnosed once all other causes are ruled out. In clinical practice however, only a limited number of organic causes are ruled out by further investigations and syndromic forms are likely to be frequently overlooked. We recommend that clinicians evaluating children with constipation examine for features suggestive of a hereditary syndrome. Recognition of such a syndrome can be of major importance for the patient, both with respect to the constipation, its treatment, and to the other manifestations of the syndrome. A detailed clinical history, with attention to the family history, physical and mental development, and co-occurrence of other physical illnesses is mandatory. A physical examination should not only include abdominal and rectal exams but should also include a complete examination from head to toe, paying attention to unusual morphological features and congenital malformations. Study of such features in larger groups of children, would allow the true prevalence of syndromic causes of childhood constipation to be known. We suggest this might be (much) higher than anticipated due to our experience in similar studies of children with other disorders such as childhood cancer 51,52 and congenital hypothyroidism.53
106 Genetics of childhood constipation
Chapter 4
Figure 1 | Ideogram showing all chromosomal regions involved in childhood constipation. OMIM numbers provided in this figure can be found in Table 1. Inheritance: ---- = autosomal recessive and autosomal dominant; underlined = autosomal dominant; not underlined = autosomal recessive
107 chapter 4
Table 1 | Syndromes associated with childhood constipation Syndrome OMIM* Major other manifestations Inheritance ** Gene/ regions of Reference chromosome Autonomic nervous system Alexander disease 203450 seizures, neurodegeneration, spasticity AD GFAP/17q21 54 Cavitating leukodystrophy - 169500 cerebellar and pyramidal failure, orthostatic hypotension, bowel AD LMNB1/ 5q23 55 autonomic failure and bladder control problems Congenital central hypoventilation 209880 hypoventilation, ocular abnormalities, Hirschsprung disease*** AD PHOX2B/4p12, 56 syndrome and many others Hereditary sensory and autonomic 201300 autonomic dysfunction, defective lacrimation, incoordination AR HSN2/12p13 31 neuropathy type II and III 223900 IKBKAP/9q31 57 MECP2 duplication 300005 MR, hypotonia, seizures, autonomic dysfunctioning, spasticity XL MECP2/ Xq28 58 Multiple sclerosis - anaemia - bilateral optic neuropathy, diplopia, spastic tetraparesis, sensory multifactorial - 59 loss, ataxia, neurogenic bladder Paroxysmal extreme pain disorder 167400 rectal pain and sphincter hypertrophy AD SCN9A/2q24 60 Pitt-Hopkins syndrome 610954 MR, overbreathing, clubbing fingers, unusual face, Hirschsprung AR TCF4/ 18q21 61 disease*** NRXN1/2p16.3 Innervation Alpha-thalassemia mental 301040 MR, alpha-thalassemia, short stature, microcephaly, unusual face, XL ATRX/Xq13 62 retardation syndrome Hirschsprung disease MEN2B 162300 multiple endocrine adenomatosis, dysmorphic features, AD RET/ 10q11 63 Hirschsprung disease, gastrointestinal ganglioneuromatosis Mowat-Wilson syndrome 235730 MR, microcephaly, unusual face, short stature, Hirschsprung AD ZEB2/ 2q22 64 disease Ochoa syndrome 236730 unusual facial expression, hydroureters,hydronephrosis AR HPSE2/10q24 33 Muscular Abdominal wall hypoplasia 612198 diastasis recti, thin abdominal wall AD - 65 Adrenomyodystrophy 300270 Primary adrenal insufficiency, dystrophic myopathy, pituitary ? - 66 microadenomas, fatty liver, megalocornea, terminal bladder ectasia Alport syndrome with diffuse 308940 hematuria, leiomyomatosis, cataracts, deafness XL COL4A5/Xq22 67 leiomyomatosis COL4A6/Xq22 Congenital generalized 613327 lipodystrophy, insulin resistance, pyloric stenosis, cardiac AR PTRF-CAVIN/ 17q21 68 lipodystrophy, type 4 arrhythmia Desmin-related myopathy 601419 Skeletal muscle weakness and cardiac problems AR DES/2q35 69 AD Hyperkalemic periodic paralysis 170500 episodic flaccid generalized muscle weakness AD SCN4A/17q23 70 (HYPP) Myotonic dystrophy 160900 myotonia, muscular dystrophy, cataract, hypogonadism, frontal AD ZNF9/ 3q21 71 602668 balding DMPK/19q13 Puerto Rican infant hypotonia 600096 MR, hypotonia, seizures, delayed bone age ? - 72 syndrome Sondheimer syndrome - MR, hypotonia,, hypertelorism, midface hypoplasia, short stature ? - 73 Spinal muscular atrophy 253300 acute spinal muscular atrophy, severe hyptonia AR SMN1/5q12 36
108 Genetics of childhood constipation
Table 1 | Syndromes associated with childhood constipation Syndrome OMIM* Major other manifestations Inheritance ** Gene/ regions of Reference chromosome Autonomic nervous system Alexander disease 203450 seizures, neurodegeneration, spasticity AD GFAP/17q21 54 Cavitating leukodystrophy - 169500 cerebellar and pyramidal failure, orthostatic hypotension, bowel AD LMNB1/ 5q23 55 autonomic failure and bladder control problems Congenital central hypoventilation 209880 hypoventilation, ocular abnormalities, Hirschsprung disease*** AD PHOX2B/4p12, 56 syndrome and many others Hereditary sensory and autonomic 201300 autonomic dysfunction, defective lacrimation, incoordination AR HSN2/12p13 31 neuropathy type II and III 223900 IKBKAP/9q31 57 MECP2 duplication 300005 MR, hypotonia, seizures, autonomic dysfunctioning, spasticity XL MECP2/ Xq28 58 Multiple sclerosis - anaemia - bilateral optic neuropathy, diplopia, spastic tetraparesis, sensory multifactorial - 59 Chapter loss, ataxia, neurogenic bladder Paroxysmal extreme pain disorder 167400 rectal pain and sphincter hypertrophy AD SCN9A/2q24 60 Pitt-Hopkins syndrome 610954 MR, overbreathing, clubbing fingers, unusual face, Hirschsprung AR TCF4/ 18q21 61 disease*** NRXN1/2p16.3 Innervation 4 Alpha-thalassemia mental 301040 MR, alpha-thalassemia, short stature, microcephaly, unusual face, XL ATRX/Xq13 62 retardation syndrome Hirschsprung disease MEN2B 162300 multiple endocrine adenomatosis, dysmorphic features, AD RET/ 10q11 63 Hirschsprung disease, gastrointestinal ganglioneuromatosis Mowat-Wilson syndrome 235730 MR, microcephaly, unusual face, short stature, Hirschsprung AD ZEB2/ 2q22 64 disease Ochoa syndrome 236730 unusual facial expression, hydroureters,hydronephrosis AR HPSE2/10q24 33 Muscular Abdominal wall hypoplasia 612198 diastasis recti, thin abdominal wall AD - 65 Adrenomyodystrophy 300270 Primary adrenal insufficiency, dystrophic myopathy, pituitary ? - 66 microadenomas, fatty liver, megalocornea, terminal bladder ectasia Alport syndrome with diffuse 308940 hematuria, leiomyomatosis, cataracts, deafness XL COL4A5/Xq22 67 leiomyomatosis COL4A6/Xq22 Congenital generalized 613327 lipodystrophy, insulin resistance, pyloric stenosis, cardiac AR PTRF-CAVIN/ 17q21 68 lipodystrophy, type 4 arrhythmia Desmin-related myopathy 601419 Skeletal muscle weakness and cardiac problems AR DES/2q35 69 AD Hyperkalemic periodic paralysis 170500 episodic flaccid generalized muscle weakness AD SCN4A/17q23 70 (HYPP) Myotonic dystrophy 160900 myotonia, muscular dystrophy, cataract, hypogonadism, frontal AD ZNF9/ 3q21 71 602668 balding DMPK/19q13 Puerto Rican infant hypotonia 600096 MR, hypotonia, seizures, delayed bone age ? - 72 syndrome Sondheimer syndrome - MR, hypotonia,, hypertelorism, midface hypoplasia, short stature ? - 73 Spinal muscular atrophy 253300 acute spinal muscular atrophy, severe hyptonia AR SMN1/5q12 36
109 chapter 4
Table 1 | Syndromes associated with childhood constipation (cont.) Syndrome OMIM* Major other manifestations Inheritance ** Gene/ regions of Reference chromosome Metabolic Aromatic L-amino acid decarboxylase 608643 MR, hypotonia, oculogyric crises, choreoathetosis AR A ADC/7p11 74 deficiency MEHMO syndrome 300148 MR, microcephaly, hypogonadism, obesity mitochondrial CYBB, DXS365/Xp21 75 XL Fabry disease 301500 angiokeratomas of the skin, limb pain, progressive renal failure, AR GLA/Xq22 39 cardiac defects, cerebrovascular accidents Familial amyloid polyneuropathy 176300 polyneuropathy, cardiomyopathy, carpal tunnel syndrome, renal AR T TR/18q11 76 insufficiency, hypotension AD MELAS 540000 myopathy, encephalopathy, raised lactic acid concentrations, mitochondrial mtDNA mutations 77 stroke Malonyl-CoA decarboxylase 248360 MR, seizures, hypotonia, vomiting, hypertrophic cardiomyopathy, AR MLYCD/16q24 78 deficiency metabolic acidosis Niemann-Pick type C 257220 progressive dementia, ophthalmoplegia, spasticity, ataxia, AR NPC1/18q11 79 seizures NPC2/14q24 Porphyria, acute intermittent / 176000 intermittent and recurrent abdominal pain, behavioural AD HMBS/ 11q23 80 variegate 176200 problems, nausea, vomiting, motor neuropathy, enlarged liver PPOX/ 1q21 and spleen Sandhoff disease - juvenile 268800 cerebellar ataxia, progressive motor neuropathy, autonomic AR HEXB/5q13 81 dysfunction, achalasia Smith-Lemli-Opitz syndrome 270400 MR, growth retardation, unusual face, hypospadia, organ AR DHCR7/ 11q12 82 malformations, cutaneous syndactyly toes Connective tissue Ehlers-Danlos syndrome type IV 130050 stretchable skin, joint hypermobility, vascular and gastrointestinal AD COL3A1/2q31 83 ruptures Ehlers-Danlos syndrome type VI-B 229200 stretchable skin, blue sclerae, keratoconus, joint hypermobility, AR ZNF469/16q24 84 corneal rupture Coordination Aicardi syndrome 304050 MR, infantile spasms, chorioretinopathy, agenesis corpus XL Xp22 85 callosum Angelman syndrome 105830 MR, microcephaly, absent speech, ataxia, seizures, outbursts of microdeletion UBE3A/ 15q11 86 laughter UPD CFC syndrome 115150 MR, unusual face, pulmonary stenosis, dry skin, sparse hair, short AR BRAF/7q34 87 stature KRAS/12p12 MEK1/19p13 SOS1/ 2p22 Floating-Harbor syndrome 136140 MR, short stature, delayed bone age, delayed speech, unusual ? - 88 face Kapur-Toriello syndrome 244300 MR, cleft lip/palate, retina and iris coloboma, ASD, VSD, unusual AR - 89 face, intestinal malrotation KBG syndrome 148050 MR, short stature, unusual face, macrodontia, block vertebrae, ? - 90 broad halluces Kaufman syndrome 244450 MR, microcephaly, unusual face, microcornea, myopia, AR - 91 hypotonia, cerebral Lindstrom syndrome - MR, short stature, unusual face, camptodactyly, cerebral atrophy ? - 92
110 Genetics of childhood constipation
Table 1 | Syndromes associated with childhood constipation (cont.) Syndrome OMIM* Major other manifestations Inheritance ** Gene/ regions of Reference chromosome Metabolic Aromatic L-amino acid decarboxylase 608643 MR, hypotonia, oculogyric crises, choreoathetosis AR A ADC/7p11 74 deficiency MEHMO syndrome 300148 MR, microcephaly, hypogonadism, obesity mitochondrial CYBB, DXS365/Xp21 75 XL Fabry disease 301500 angiokeratomas of the skin, limb pain, progressive renal failure, AR GLA/Xq22 39 cardiac defects, cerebrovascular accidents Familial amyloid polyneuropathy 176300 polyneuropathy, cardiomyopathy, carpal tunnel syndrome, renal AR T TR/18q11 76 insufficiency, hypotension AD MELAS 540000 myopathy, encephalopathy, raised lactic acid concentrations, mitochondrial mtDNA mutations 77 stroke Chapter Malonyl-CoA decarboxylase 248360 MR, seizures, hypotonia, vomiting, hypertrophic cardiomyopathy, AR MLYCD/16q24 78 deficiency metabolic acidosis Niemann-Pick type C 257220 progressive dementia, ophthalmoplegia, spasticity, ataxia, AR NPC1/18q11 79 seizures NPC2/14q24 4 Porphyria, acute intermittent / 176000 intermittent and recurrent abdominal pain, behavioural AD HMBS/ 11q23 80 variegate 176200 problems, nausea, vomiting, motor neuropathy, enlarged liver PPOX/ 1q21 and spleen Sandhoff disease - juvenile 268800 cerebellar ataxia, progressive motor neuropathy, autonomic AR HEXB/5q13 81 dysfunction, achalasia Smith-Lemli-Opitz syndrome 270400 MR, growth retardation, unusual face, hypospadia, organ AR DHCR7/ 11q12 82 malformations, cutaneous syndactyly toes Connective tissue Ehlers-Danlos syndrome type IV 130050 stretchable skin, joint hypermobility, vascular and gastrointestinal AD COL3A1/2q31 83 ruptures Ehlers-Danlos syndrome type VI-B 229200 stretchable skin, blue sclerae, keratoconus, joint hypermobility, AR ZNF469/16q24 84 corneal rupture Coordination Aicardi syndrome 304050 MR, infantile spasms, chorioretinopathy, agenesis corpus XL Xp22 85 callosum Angelman syndrome 105830 MR, microcephaly, absent speech, ataxia, seizures, outbursts of microdeletion UBE3A/ 15q11 86 laughter UPD CFC syndrome 115150 MR, unusual face, pulmonary stenosis, dry skin, sparse hair, short AR BRAF/7q34 87 stature KRAS/12p12 MEK1/19p13 SOS1/ 2p22 Floating-Harbor syndrome 136140 MR, short stature, delayed bone age, delayed speech, unusual ? - 88 face Kapur-Toriello syndrome 244300 MR, cleft lip/palate, retina and iris coloboma, ASD, VSD, unusual AR - 89 face, intestinal malrotation KBG syndrome 148050 MR, short stature, unusual face, macrodontia, block vertebrae, ? - 90 broad halluces Kaufman syndrome 244450 MR, microcephaly, unusual face, microcornea, myopia, AR - 91 hypotonia, cerebral Lindstrom syndrome - MR, short stature, unusual face, camptodactyly, cerebral atrophy ? - 92
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Table 1 | Syndromes associated with childhood constipation (cont.) Syndrome OMIM* Major other manifestations Inheritance ** Gene/ regions of Reference chromosome Posterior column ataxia with retinitis 609033 posterior column ataxia, retinitis pigmentosa, oesophageal AR AXPC1/1q31 43 pigmentosa achalasia Rubinstein-Taybi syndrome 180849 MR, broad thumbs, broad halluces, unusual face, growth AD CBP/ 16p13 93 retardation microdeletion EP300/22q13 Stevenson-Carey syndrome 611961 MR, unusual face, Pierre-Robin sequence, cerebellar hypoplasia, ? - 94 camptodactyly Turner mental retardation syndrome 300706 MR, macrocephaly, contractures, holoprosencephaly XL HUWE1/ Xp11 95 X-linked syndromic mental 300676 MR, hypotonia, slender body build, long face XL UPF3B/ Xq25 96 retardation -14 Water-electrolyte balance Gitelman syndrome 263800 hypokalemic metabolic alkalosis, salt wasting AR SLC12A3/ 16q13 45 Creatinine transporter defect 300036 MR, hypotonia, seizures, behavioural problems XL SLC6A8/ Xq28 97 Hyperparathyroidism - neonatal 239200 hypotonia, respiratory distress, irritability, polyuria AD CASR/ 3q21 98 familial Nephrogenic diabetes insipidus 304800 vomiting, anorexia, failure to thrive, fever XL AVPR2/Xq28 99 Netherton syndrome 256500 ichthyosis, eczema, brittle hair, alopecia AR SPINK5/ 5q32 100 Malformation Currarino syndrome 176450 anal atresia, sacral anomalies, presacral mass AD HLXB9/7q36 46 Emphysema-genital anomalies; 602564 MR, emphysema, penoscrotal web, deafness, obesity ? - 101 deafness; MR FG syndrome 305450 MR, macrocephaly, anal malformation, pyloric stenosis, XL MED12/ Xq13 102 hypotonia FLNA/Xq28 Holoprosencephaly 157170 MR, microcephaly, cleft lip, cleft palate, hypotelorism, sacral AD SIX3/2p21 103 agenesis, holoprosencephaly Proteus syndrome 176920 MR, postnatal overgrowth, skin lesions, vascular malformations, ? - 104 lipoma, lipodystrophy Sacral defect with anterior 600145 caudal dysgenesis AD VANGL1/ 1p13 105 meningocele Chromosome Translocation (1;22)(p36;q13) - MR, short stature, unusual face, seizures, cerebral atrophy, C - 106 feeding difficulties, sleep disturbances, hypotonia Triplication 4q32.1 - MR, macrocephaly, unusual face, hypoplastic zygoma, C - 107 Hirschsprung disease Deletion 5p15 123450 MR, cat-like cry, unusual face, microcephaly C - 108 (Cri-du-chat syndrome) Duplication 7q11.2 - MR, unusual face, behavioural problems C - 109 Deletion 7q11.2 194050 MR, unusual face, aortic stenosis, neonatal hypercalcemia C - 110 (Williams syndrome) Deletion 11q23 147791 MR, growth retardation, trigonocephaly, camptodactyly, C - 111 (Jacobsen syndrome) hammertoes, thrombocytopenia, unusual face Duplication 12q24 - MR, unusual face, speech disturbance, ptosis, Marcus-Gunn C - 112 phenomenon Paternal uniparental disomy 20 - MR, microtia, microcephaly, neuronal subependymal C - 113 heterotopias, Hirschsprung disease
112 Genetics of childhood constipation
Table 1 | Syndromes associated with childhood constipation (cont.) Syndrome OMIM* Major other manifestations Inheritance ** Gene/ regions of Reference chromosome Posterior column ataxia with retinitis 609033 posterior column ataxia, retinitis pigmentosa, oesophageal AR AXPC1/1q31 43 pigmentosa achalasia Rubinstein-Taybi syndrome 180849 MR, broad thumbs, broad halluces, unusual face, growth AD CBP/ 16p13 93 retardation microdeletion EP300/22q13 Stevenson-Carey syndrome 611961 MR, unusual face, Pierre-Robin sequence, cerebellar hypoplasia, ? - 94 camptodactyly Turner mental retardation syndrome 300706 MR, macrocephaly, contractures, holoprosencephaly XL HUWE1/ Xp11 95 X-linked syndromic mental 300676 MR, hypotonia, slender body build, long face XL UPF3B/ Xq25 96 retardation -14 Water-electrolyte balance Chapter Gitelman syndrome 263800 hypokalemic metabolic alkalosis, salt wasting AR SLC12A3/ 16q13 45 Creatinine transporter defect 300036 MR, hypotonia, seizures, behavioural problems XL SLC6A8/ Xq28 97 Hyperparathyroidism - neonatal 239200 hypotonia, respiratory distress, irritability, polyuria AD CASR/ 3q21 98 familial Nephrogenic diabetes insipidus 304800 vomiting, anorexia, failure to thrive, fever XL AVPR2/Xq28 99 4 Netherton syndrome 256500 ichthyosis, eczema, brittle hair, alopecia AR SPINK5/ 5q32 100 Malformation Currarino syndrome 176450 anal atresia, sacral anomalies, presacral mass AD HLXB9/7q36 46 Emphysema-genital anomalies; 602564 MR, emphysema, penoscrotal web, deafness, obesity ? - 101 deafness; MR FG syndrome 305450 MR, macrocephaly, anal malformation, pyloric stenosis, XL MED12/ Xq13 102 hypotonia FLNA/Xq28 Holoprosencephaly 157170 MR, microcephaly, cleft lip, cleft palate, hypotelorism, sacral AD SIX3/2p21 103 agenesis, holoprosencephaly Proteus syndrome 176920 MR, postnatal overgrowth, skin lesions, vascular malformations, ? - 104 lipoma, lipodystrophy Sacral defect with anterior 600145 caudal dysgenesis AD VANGL1/ 1p13 105 meningocele Chromosome Translocation (1;22)(p36;q13) - MR, short stature, unusual face, seizures, cerebral atrophy, C - 106 feeding difficulties, sleep disturbances, hypotonia Triplication 4q32.1 - MR, macrocephaly, unusual face, hypoplastic zygoma, C - 107 Hirschsprung disease Deletion 5p15 123450 MR, cat-like cry, unusual face, microcephaly C - 108 (Cri-du-chat syndrome) Duplication 7q11.2 - MR, unusual face, behavioural problems C - 109 Deletion 7q11.2 194050 MR, unusual face, aortic stenosis, neonatal hypercalcemia C - 110 (Williams syndrome) Deletion 11q23 147791 MR, growth retardation, trigonocephaly, camptodactyly, C - 111 (Jacobsen syndrome) hammertoes, thrombocytopenia, unusual face Duplication 12q24 - MR, unusual face, speech disturbance, ptosis, Marcus-Gunn C - 112 phenomenon Paternal uniparental disomy 20 - MR, microtia, microcephaly, neuronal subependymal C - 113 heterotopias, Hirschsprung disease
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Table 1 | Syndromes associated with childhood constipation (cont.) Syndrome OMIM* Major other manifestations Inheritance ** Gene/ regions of Reference chromosome Trisomy 21 190685 MR, unusual face, broad chest, hypotonia, broad hands and C - 114 (Down Syndrome) feet, achalasia, GERD, pyloric stenosis, Hirschsprung disease Deletion 22q11 188400 MR, unusual face, congenital heart defects, impaired C - 115 (velocardiofacial syndrome) immunological functioning Deletion 22q13 606232 MR, hypotonia, behavioural abnormalities, unusual face C - 116 Duplication Xp22.3 - MR, unusual face, microcephaly, foetal finger pads C - 117 Duplication Xq28 300815 MR, hypotonia, unusual face, increased infection rate C - 118 Unknown ADPHSP 182601 Pure hereditary spastic paraplegia AD SPG4/ 2p21 119 AEC syndrome 106260 ectodermal dysplasia, ankyloblepharon, cleft lip, cleft palate AD TP63/ 3q27 120 Celiac disease 212750 intestinal malabsorption, failure to thrive, malnutrition multifactorial CELIAC1/6p21 and 121 many others Dystrophic epidermolysis bullosa 131750/ severe blistering, strictures of gastrointestinal tract AD, AR COL7A1, MMP1/3p21, 122 226600 11q22-11q23 Gardner (1983) syndrome - MR, thrombocytopenia, VSD, hypotonia AR - 123 Ichthyosiform erythroderma – aortic - MR, bullous ichthyosiform erythroderma, aortic and pulmonary ? FRA12A?/ 12q13? 124 and pulmonary stenosis stenosis, PDA Noonan syndrome 163950 short stature, unusual face, webbed neck, pulmonary stenosis, AD PTPN11/12q24 125 pectus excavatum, motor delay, bleeding diathesis KRAS/12p12 SOS1/ 2p22 RAF1/3p25 NRAS/1p13.2 * OMIM: Online Mendelian Inheritance in Man: www.ncbi.nlm.nih.gov/omim; ** Inheritance: XL; X-linked; AR; autosomal recessive; AD; autosomal dominant; C; chromosomal; *** in most patients no Hirschsprung disease is present while they still have constipation; a disturbed innervation is present in them
114 Genetics of childhood constipation
Table 1 | Syndromes associated with childhood constipation (cont.) Syndrome OMIM* Major other manifestations Inheritance ** Gene/ regions of Reference chromosome Trisomy 21 190685 MR, unusual face, broad chest, hypotonia, broad hands and C - 114 (Down Syndrome) feet, achalasia, GERD, pyloric stenosis, Hirschsprung disease Deletion 22q11 188400 MR, unusual face, congenital heart defects, impaired C - 115 (velocardiofacial syndrome) immunological functioning Deletion 22q13 606232 MR, hypotonia, behavioural abnormalities, unusual face C - 116 Duplication Xp22.3 - MR, unusual face, microcephaly, foetal finger pads C - 117 Duplication Xq28 300815 MR, hypotonia, unusual face, increased infection rate C - 118 Unknown ADPHSP 182601 Pure hereditary spastic paraplegia AD SPG4/ 2p21 119 AEC syndrome 106260 ectodermal dysplasia, ankyloblepharon, cleft lip, cleft palate AD TP63/ 3q27 120 Chapter Celiac disease 212750 intestinal malabsorption, failure to thrive, malnutrition multifactorial CELIAC1/6p21 and 121 many others Dystrophic epidermolysis bullosa 131750/ severe blistering, strictures of gastrointestinal tract AD, AR COL7A1, MMP1/3p21, 122 226600 11q22-11q23 syndrome 4 Gardner (1983) - MR, thrombocytopenia, VSD, hypotonia AR - 123 Ichthyosiform erythroderma – aortic - MR, bullous ichthyosiform erythroderma, aortic and pulmonary ? FRA12A?/ 12q13? 124 and pulmonary stenosis stenosis, PDA Noonan syndrome 163950 short stature, unusual face, webbed neck, pulmonary stenosis, AD PTPN11/12q24 125 pectus excavatum, motor delay, bleeding diathesis KRAS/12p12 SOS1/ 2p22 RAF1/3p25 NRAS/1p13.2 * OMIM: Online Mendelian Inheritance in Man: www.ncbi.nlm.nih.gov/omim; ** Inheritance: XL; X-linked; AR; autosomal recessive; AD; autosomal dominant; C; chromosomal; *** in most patients no Hirschsprung disease is present while they still have constipation; a disturbed innervation is present in them
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87. Herman TE, McAlister WH. Gastrointestinal and renal abnormalities in cardio-facio-cutaneous syndrome. Pediatr Radiol. 2005;35:202-205. 88. Karaer K, Karaoguz MY, Ergun MA, Yesilkaya E, Bideci A, Percin EF. Floating-Harbor syndrome: a first female Turkish patient? Genet Couns. 2006;17:465-468. 89. Zelante L, Candela MA, Savoia A, Gasparini P. Confirmation of Kapur-Toriello syndrome in an Italian patient. Clin Dysmorphol. 1999;8:151-153. 90. Devriendt K, Holvoet M, Fryns JP. Further delineation of the KBG syndrome. Genet Couns. 1998;9:191-194. 91. Kaufman RL, Rimoin DL, Prensky AL, Sly WS. An oculocerebrofacial syndrome. Birth Defects Orig Artic Ser. 1971;7:135-138. 92. Lindstrom JA. Oligophrenic, low birthweight dwarfism in sibs. Birth Defects Orig Artic Ser. 1975;11:443- 449. 93. Hennekam RC, Van Den Boogaard MJ, Sibbles BJ, Van Spijker HG. Rubinstein-Taybi syndrome in The Netherlands. Am J Med Genet Suppl. 1990;6:17-29. 94. Stevenson DA, Carey JC. A novel multiple congenital anomaly-mental retardation syndrome with Pierre Robin sequence and cerebellar hypoplasia in two sisters. Am J Med Genet A. 2007;143A:2221-2226. 95. Froyen G, Corbett M, Vandewalle J, Jarvela I, Lawrence O, Meldrum C, et al. Submicroscopic duplications of the hydroxysteroid dehydrogenase HSD17B10 and the E3 ubiquitin ligase HUWE1 are associated with mental retardation. Am J Hum Genet. 2008;82:432-443. 96. Tarpey PS, Raymond FL, Nguyen LS, Rodriguez J, Hackett A, Vandeleur L, et al. Mutations in UPF3B, a member of the nonsense-mediated mRNA decay complex, cause syndromic and nonsyndromic mental retardation. Nat Genet. 2007;39:1127-1133. 97. van de Kamp JM, Mancini GM, Pouwels PJ, Betsalel OT, van Dooren SJ, de K, I, et al. Clinical features and X-inactivation in females heterozygous for creatine transporter defect. Clin Genet. 2010. 98. Lillquist K, Illum N, Jacobsen BB, Lockwood K. Primary hyperparathyroidism in infancy associated with familial hypocalciuric hypercalcemia. Acta Paediatr Scand. 1983;72:625-629. 99. van Lieburg AF, Knoers NV, Monnens LA. Clinical presentation and follow-up of 30 patients with congenital nephrogenic diabetes insipidus. J Am Soc Nephrol. 1999;10:1958-1964. 100. Andre E, Till M, Descargues P, Cordier MP, Fouilhoux A, Haftek M, et al. [Netherton syndrome: a type of infantile erythroderma with failure to thrive, immune deficiency, rickets. Report of 3 cases]. Arch Pediatr. 2005;12:1364-1367. 101. Lynch SA, Bushby KM. Congenital emphysema, cryptorchidism, penoscrotal web, deafness, and mental retardation--a new syndrome? Clin Dysmorphol. 1997;6:35-37. 102. Romano C, Baraitser M, Thompson E. A clinical follow-up of British patients with FG syndrome. Clin Dysmorphol. 1994;3:104-114. 103. Martin AO, Perrin JC, Muir WA, Ruch E, Schafer IA. An autosomal dominant midline cleft syndrome resembling familial holoprosencephaly. Clin Genet. 1977;12:65-72. 104. Mackay G, Spitz L, McHugh K. Lipomatosis of the colon complicating Proteus syndrome. Arch Dis Child. 2002;86:265. 105. Gardner PA, Albright AL. “Like mother, like son:” hereditary anterior sacral meningocele. Case report and review of the literature. J Neurosurg. 2006;104:138-142. 106. Gajecka M, Saadeh R, Mackay KL, Glotzbach CD, Spodar K, Chitayat D, et al. Clinical and molecular cytogenetic characterization of four patients with unbalanced translocation der(1)t(1;22)(p36;q13). Am J Med Genet A. 2008;146A:2777-2784. 107. Wang JC, Fisker T, Dang L, Teshima I, Nowaczyk MJ. 4.3-Mb triplication of 4q32.1-q32.2: report of a family through two generations. Am J Med Genet A. 2009;149A:2274-2279.
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108. Wilkins LE, Brown JA, Nance WE, Wolf B. Clinical heterogeneity in 80 home-reared children with cri du chat syndrome. J Pediatr. 1983;102:528-533. 109. Berg JS, Brunetti-Pierri N, Peters SU, Kang SH, Fong CT, Salamone J, et al. Speech delay and autism spectrum behaviors are frequently associated with duplication of the 7q11.23 Williams-Beuren syndrome region. Genet Med. 2007;9:427-441. 110. Morris CA, Leonard CO, Dilts C, Demsey SA. Adults with Williams syndrome. Am J Med Genet Suppl. 1990;6:102-107. 111. Bernaciak J, Szczaluba K, Derwinska K, Wisniowiecka-Kowalnik B, Bocian E, Sasiadek MM, et al. Clinical and molecular-cytogenetic evaluation of a family with partial Jacobsen syndrome without thrombocytopenia caused by an approximately 5 Mb deletion del(11)(q24.3). Am J Med Genet A. 2008;146A:2449-2454. 112. Doco-Fenzy M, Mauran P, Lebrun JM, Bock S, Bednarek N, Struski S, et al. Pure direct duplication (12) (q24.1-->q24.2) in a child with Marcus Gunn phenomenon and multiple congenital anomalies. Am J Med Genet A. 2006;140:212-221. Chapter 113. Venditti CP, Hunt P, Donnenfeld A, Zackai E, Spinner NB. Mosaic paternal uniparental (iso)disomy for chromosome 20 associated with multiple anomalies. Am J Med Genet A. 2004;124A:274-279. 114. Moore SW. Down syndrome and the enteric nervous system. Pediatr Surg Int. 2008;24:873-883. 115. Eicher PS, McDonald-Mcginn DM, Fox CA, Driscoll DA, Emanuel BS, Zackai EH. Dysphagia in children with a 22q11.2 deletion: unusual pattern found on modified barium swallow. J Pediatr. 2000;137:158-164. 4 116. de Vries BB, Bitner-Glindzicz M, Knight SJ, Tyson J, MacDermont KD, Flint J, et al. A boy with a submicroscopic 22qter deletion, general overgrowth and features suggestive of FG syndrome. Clin Genet. 2000;58:483-487. 117. Tyson C, Harvard C, Locker R, Friedman JM, Langlois S, Lewis ME, et al. Submicroscopic deletions and duplications in individuals with intellectual disability detected by array-CGH. Am J Med Genet A. 2005;139:173-185. 118. Prescott TE, Rodningen OK, Bjornstad A, Stray-Pedersen A. Two brothers with a microduplication including the MECP2 gene: rapid head growth in infancy and resolution of susceptibility to infection. Clin Dysmorphol. 2009;18:78-82. 119. Namekawa M, Takiyama Y, Sakoe K, Shimazaki H, Amaike M, Niijima K, et al. A large Japanese SPG4 family with a novel insertion mutation of the SPG4 gene: a clinical and genetic study. J Neurol Sci. 2001;185:63- 68. 120. Motil KJ, Fete TJ. Growth, nutritional, and gastrointestinal aspects of ankyloblepharon-ectodermal defect- cleft lip and/or palate (AEC) syndrome. Am J Med Genet A. 2009;149A:1922-1925. 121. Rashid M, Cranney A, Zarkadas M, Graham ID, Switzer C, Case S, et al. Celiac disease: evaluation of the diagnosis and dietary compliance in Canadian children. Pediatrics. 2005;116:e754-e759. 122. Freeman EB, Koglmeier J, Martinez AE, Mellerio JE, Haynes L, Sebire NJ, et al. Gastrointestinal complications of epidermolysis bullosa in children. Br J Dermatol. 2008;158:1308-1314. 123. Gardner RJ, Morrison PS, Abbott GD. A syndrome of congenital thrombocytopenia with multiple malformations and neurologic dysfunction. J Pediatr. 1983;102:600-602. 124. Berg J, Grace E, Teik KW, Hammond H, Tidman M, FitzPatrick D. Bullous ichthyosiform erythroderma, developmental delay, aortic and pulmonary stenosis in association with a FRA12A. Clin Dysmorphol. 2000;9:213-219. 125. Shah N, Rodriguez M, Louis DS, Lindley K, Milla PJ. Feeding difficulties and foregut dysmotility in Noonan’s syndrome. Arch Dis Child. 1999;81:28-31.
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Chapter 5
Symptoms of Autism Spectrum Disorders in Children with Functional Defecation Disorders
Babette Peeters, Ilse Noens, Elise M. Philips, Sofie Kuppens, Marc A. Benninga
Submitted chapter 5
Abstract Objective In children with autism spectrum disorders (ASD), a remarkably high prevalence of functional defecation disorders (FDD) has been found. This study prospectively assesses the prevalence of ASD symptoms in children presenting with FDD.
Study design Children (4 -12 yrs) with functional constipation (FC) or functional non-retentive fecal incontinence (FNRFI) according to the ROME III criteria referred to a specialized outpatient clinic were included. Parents completed two validated ASD screening questionnaires about their child; the Social Responsiveness Scale (SRS) and the Social Communication Questionnaire Lifetime (SCQ-L). A total SRS score of ≥51 is a strong indicator for the presence of ASD. On the SCQ-L, a score of ≥15 is suggestive for ASD.
Results In total, 242 patients (130 males, median age 7.9) were included. Of these, 91% were diagnosed with FC and 9% with FNRFI. Thirteen children (5.4%) had previously been diagnosed with ASD. Twenty-six children (11%) had both SRS and SCQ-L scores at or above cutoff points, strongly suggestive for the presence of ASD. Solely high SRS were present in 42 children (17%), whereas two children (1%) only had high SCQ-L scores. Altogether, 29% had ASD symptoms, indicated by SRS and/or SCQ-L scores at or above the cut off values. These children were older than children without ASD symptoms and presented with a longer duration of symptoms.
Conclusions A substantial amount of children (29%) presenting with FDD at a tertiary hospital has concomitant ASD symptoms. Clinicians should be aware of ASD symptoms in children with FDD.
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Introduction Functional defecation disorders (FDD), functional constipation (FC) and functional non-retentive fecal incontinence (FNRFI), are common problems in children. The world-wide prevalence of functional constipation (FC) in children ranges from 0.7 to 29.6 %. 1 Fecal impaction may lead to fecal incontinence which can be a source of considerable distress and embarrassment for the child and the family. In some children, fecal incontinence may occur without signs of fecal retention better known as ‘functional non-retentive fecal incontinence’ (FNRFI).2 FNRFI has a reported prevalence of 1.5 to 9.8% in children.3 The internationally accepted ROME III diagnostic criteria for FC and FNRFI are tabulated in Table I.2 Despite maximal appliance of current conservative treatment modalities, long term follow- up data show that FDD symptoms persist into adulthood in 25-30% of children, negatively affecting quality of life.4 The pathophysiology of FDD is multifactorial and largely unknown. Genetic factors are thought to play a role, but also environmental factors, behavior problems and child-parent Chapter interactions may contribute to the etiology and persistence of symptoms.5,6 Interestingly, a high prevalence of gastrointestinal disorders, most frequently being constipation, has been reported in children with autism spectrum disorders (ASD).7-11 ASD represent three of the pervasive developmental disorders defined in the Diagnostic and Statistical Manual 5 of Mental disorders (DSM-IV-TR): autistic disorder, Asperger syndrome and pervasive developmental disorder – not otherwise specified (PDD-NOS).12 Individuals affected by ASD may share a common triad of impairment in social interactions, impaired and atypical verbal and non-verbal communication, and repetitive and unusual behavior and play.13 The prevalence of ASD in children in the general population is estimated to range from
Table I | Diagnostic ROME III criteria for functional constipation and functional non-retentive fecal incontinence Functional constipation (FC)2 Functional non-retentive fecal incontinence (FNRFI)2 Must include 2 or more of the following in a child with Must include all of the following in a child with a a developmental age of at least 4 years with insufficient developmental age at least 4 years: criteria for diagnosis of IBS: 1. Two or fewer defecations per week 1. Defecation into places inappropriate to the social context at least once per month 2. At least 1 episode of fecal incontinence per week 2. No evidence of an inflammatory, anatomic, metabolic, or neoplastic process that explains the subject’s symptoms 3. History of retentive posturing or excessive volitional 3. No evidence of fecal retention stool retention 4. History of painful or hard bowel movements 5. Presence of a large fecal mass in the rectum 6. History of large diameter stools that may obstruct the toilet
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0.6 to 0.7%.14 Recent data from the United States however provide evidence for a current prevalence over 1% (11.3 per 1.000).15 Reliable data on the prevalence of ASD symptoms in children presenting with FDD, diagnosed according to internationally accepted criteria, are sparse. Recently, a retrospective study was published investigating the prevalence of a history of diagnosed ASD in children with FC according to the former ROME II criteria.16 Nearly 8.5% of the children were reported to have an ASD history. An Australian study investigated self-reported ASD traits in young adults who had been referred for gastrointestinal symptoms in early life. Constipation was not defined by validated criteria and a broad spectrum of symptoms was considered to be the result of constipation. No relation between gastrointestinal symptoms in early life and ASD traits in young adulthood could be demonstrated.17 A validated assessment of the prevalence of ASD symptoms in children presenting with FDD is needed to further clarify the possible association between the two disorders and to obtain better insight in the complex pathophysiology of both FDD and ASD. Moreover, confirming a high prevalence of ASD symptoms in children with FDD may give rise to an adaptation of the current standard diagnostic work-up and therapeutic strategies for FDD in children. In this study, we prospectively and systematically assessed the prevalence of ASD symptoms in children presenting with FDD.
Study design
Study population A prospective cohort study was carried out between September 2009 and October 2011 in a specialized tertiary referral center for children with FDD at the Emma Children’s Hospital, Academic Medical Centre in Amsterdam, The Netherlands. A total of 302 consecutive children, aged 4-12 years, presenting at the outpatient clinic with a diagnosis of FC or FNRFI according to the internationally accepted ROME III criteria were asked to participate in this study. Patients were excluded from participation if they suffered from known pathology causing constipation and/or fecal incontinence, such as chronic inflammatory bowel disease, celiac disease, or when they had a history of large bowel surgery, congenital anorectal malformations, neurological disease (complete spinal cord transection, multiple sclerosis or spina bifida) or a genetic syndrome. Furthermore, patients with a known intellectual disability and/or an intelligence quotient of less than 70 were excluded. After giving informed consent, parents filled out two specific ASD screening questionnaires about their child. With a known prevalence of ASD in the normal population of 0.6%, a sample size of 223 children would be required to achieve a power of 80% with an alpha
126 Symptoms of autism spectrum disorders of 5% to detect a difference in prevalence that is at least 5 times higher than in the normal population. This study was approved by the Medical Ethics Committee of the Academic Medical Center in Amsterdam.
Instruments Standardized defecation questionnaire During the first visit at the outpatient clinic, as part of our routine procedure, a standardized defecation questionnaire was filled out by the medical doctor. This defecation questionnaire consists of questions about the medical history of the child, social environment, presence of a prior ASD diagnosis, medication use and specific questions about the defecation pattern based on the ROME III criteria. A prior ASD diagnosis was defined as a diagnosis according to the DSM-IV-TR criteria made by a multidisciplinary team.
Social Responsiveness Scale The Social Responsiveness Scale (SRS) is a validated 65-item quantitative ASD screening Chapter questionnaire developed in 2005 to assess a wide range of interpersonal behavior, communication and repetitive/stereotypic behavior characteristics of ASD.18 Items are scored on a 4-point scale, ranging from ‘not true’ to ‘always true’. The raw total score ranges from 0 to 195, with higher scores indicating more ASD symptoms. In 2011, the cut 5 off value for raw scores in the Dutch population with normal intelligence was set at 51, with a score of ≥51 being suggestive for a diagnosis of ASD with a sensitivity of .90 and a specificity of .88 for both males and females.19 The manual also provides T-scores for clinical use, with T=60 being the proposed cut off for clinically significant ASD traits. The SRS has proven to be a reliable and valid instrument, with good psychometric properties and discriminant validity and good agreement with the Autism Diagnostic Interview – Revised.20
Social Communication Questionnaire-Lifetime The Social Communication Questionnaire (SCQ) is a validated quantitative screening questionnaire for ASD in children of 4 years and older developed in 2003.21 The SCQ consists of 40 yes or no items to be completed by the parent resulting in a total score between 0 and 40. The agreement between SCQ scores and scores on the more extensive Autism Diagnostic Interview is high. The SCQ-Lifetime (SCQ-L) version of the SCQ aims at traits of ASD in the entire developmental history of children. A total score of ≥15 on the SCQ-L is suggestive for the presence of ASD with a sensitivity of .90 and a specificity of .80.21 The reliability and validity of the Dutch version of the SCQ-L have been approved.22
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Outcome The primary outcome is the prevalence of ASD symptoms in children with FDD. The presence of ASD symptoms was defined as a score at or above the cut off value on one or two ASD screening questionnaires (total raw SRS score of ≥51 and/or total SCQ-L score of ≥15). Scoring at or above the cut off value on one of the two questionnaires was considered to be suggestive for the presence of an ASD. Scoring at or above the cut off values of both questionnaires was considered to be very suggestive for the presence of an ASD. The secondary outcome is the difference in clinical characteristics between patients with and without ASD symptoms.
Statistical Analysis For all statistical analyses SPSS version 16.0 (SPSS Inc, Chicago Ill) was used. Missing SRS values were imputed by the median value of the standardization sample; missing SCQ values by the normative (derived) score (0). A maximum of 10 percent missing values was considered acceptable. Total raw scores on the SRS and total raw scores on the SCQ-L were analyzed as continuous variables. For the comparison of proportions, Chi square analyses were performed. Fisher exact tests were performed to compare proportions with an observed or expected frequency of less than 5. Continuous data were compared by independent t-tests when normally distributed. For the comparison of skewed continuous data, Mann-Whitney U tests were performed. The significance level was set at <.05.
Results
Demographics Out of 302 patients, parents of three patients refused to participate. The response rate was 83%; parents of a total of 250 patients returned both ASD screening questionnaires. Three patients were excluded because of a known IQ <70 and one because of a chromosomal abnormality (22q11 deletion) known to be associated with both constipation and ASD.5,23 Because four patients had to be excluded due to too many missing values, data of 242 patients were used in the analyses. Thirty-five percent of the patients were referred to the outpatient clinic by a general practitioner (GP) and had never been treated by a pediatrician or pediatric gastroenterologist for their FDD. Baseline characteristics of the 242 patients included in the analyses are depicted in Table II. Of all 242 participating children, 133 (55%) were male. Median age of participants was 7.9 years (IQR 5.7-9.5). Only 9% of the patients were diagnosed with FNRFI, all other patients fulfilled the criteria of FC. The majority of FC patients (76%) suffered from fecal incontinence.
128 Symptoms of autism spectrum disorders
Table II | Demographics Patients N 242 Male 133 (55%) Median age in years 7.9 (IQR 5.7 - 9.5) Diagnosis functional constipation without fecal incontinence 53 (22%) Diagnosis functional constipation with fecal incontinence 167 (69%) Diagnosis functional non-retentive fecal incontinence 22 (9%) Median age start symptoms in years 3.0 (IQR 0.5 - 4.0) Duration of symptoms in years 4.7 (IQR 2.9 - 6.9) Treated by general practitioner only 84 (35%) Known with autism spectrum disorder 13 (5.4%) Autism spectrum disorder previously suspected 4 (2%) Use of psychopharmaca 5 (2%) IQR = Inter Quartile Range
Chapter FDD symptoms had started at a median age of 3.0 years (IQR 0.5-4.0) and the median duration of symptoms was 4.7 years (IQR 2.9-6.9). In thirteen patients (5.4%), a diagnosis of ASD had previously been made. Of these, one child was diagnosed with classical autism, two with Asperger Syndrome and ten with PDD-NOS. Ten out of these thirteen patients 5 suffered from FC and the remaining three patients fulfilled the criteria of FNRFI. In another four participants, the presence of ASD had been suspected previously but no definite diagnosis had yet been made. In five children, the use of psychopharmaca registered for treatment of ADHD symptoms was reported.
ASD symptoms SRS and SCQ-L scores were calculated for all 242 children and are summarized in Table III. Sixty-eight patients (28%) scored at or above the SRS cut off value, whereas 28 patients (12%) scored at or above the SCQ-L cut off value. Of all participants, 26 (11%) scored above the critical values of both questionnaires. Critical scores on the SRS only were found in 42 patients (17%), two patients (1%) only exceeded the SCQ-L cut off value. The percentage of children with ASD symptoms on one or two of the screening questionnaires in the group of constipated children did not differ significantly from the percentage found in FNRFI patients (28% vs. 41% resp., X2=1.69, p=.19). Altogether, 29% (n = 70) of the participating children with FDD had ASD symptoms as indicated by SRS and/or SCQ-L scores above the cut off value. All 13 children (5.4%) with a prior diagnosis of ASD had critical scores on one (n = 3) or two ASD (n = 10) screening questionnaires in this study. Of the four participants for whom the presence of ASD had
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Table III | Presence of symptoms of autism spectrum disorders Patients (n=242) Median SRS score 30 (IQR 18 - 56) Median SRS t -score 48 (IQR 43 - 60) Cases with SRS score ≥ cut off value 68 (28%) Median SCQ-L score 5 (IQR 3 - 9) Cases with SCQ-L score ≥ cut off value 28 (12%) Cases with SRS or SCQ-L ≥ cut off value 44 (18 %) Cases with both SRS and SCQ-L ≥ cut off value 26 (11 %) ASD symptoms 70 (29%) SRS = Social Responsiveness Scale; SCQ-L = Social Communication Questionnaire-Lifetime; IQR = Inter Quartile Range; ASD = Autism Spectrum Disorder been suspected previously, three scored above the cut off values of both questionnaires and one only had critical SRS scores.
Clinical characteristics of patients with and without ASD symptoms Clinical characteristics of children with ASD symptoms were compared with those of children without ASD symptoms according to the two screening questionnaires (see Table IV). The 70 children with ASD symptoms were significantly older at time of presentation than their peers with normal scores on both questionnaires (8.4 vs. 7.7 years, U=4962; z=-2.14; p=0.032). Sex distribution and type of functional defecation disorder did not differ significantly between the groups. Children with ASD symptoms had a significantly longer
Table IV | Clinical characteristics of patients with and without symptoms of autism spectrum disorders according to SRS and/or SCQ-L No ASD symptoms ASD symptoms + p-value N 172 (71%) 70 (29%) - Male 90 (52%) 43 (61%) 0.197 Median age in years 7.7 (IQR 5.5 - 9.4) 8.4 (IQR 6.6 - 10.3) 0.032* Diagnosis FC without FI 43 (25%) 10 (14%) 0.068 Diagnosis FC with FI 116 (67%) 51 (73%) 0.409 Diagnosis FNRFI 13 (8%) 9 (13%) 0.194 Median age start symptoms in years 3.0 (IQR 0.5 - 4.0) 3.0 (IQR 0 - 4.0) 0.962 Median duration of symptoms in years 4.5 (IQR 2.6 - 6.5) 5.5 (IQR 3.6 - 7.7) 0.025* Treated by general practitioner only 58 (34%) 26 (37%) 0.295 Use of psychopharmaca 0 (0%) 5 (7%) <0.001* Previously diagnosed with ASD 0 (0%) 13 (19%) <0.001* ASD = Autism Spectrum Disorder; SRS = Social Responsiveness Scale; SCQ-L = Social Communication Questionnaire- Lifetime; IQR = Inter Quartile Range; FC = Functional Constipation; FI = Fecal Incontinence; FNRFI = Functional Non-Retentive Fecal Incontinence; * = statistically significant
130 Symptoms of autism spectrum disorders duration of symptoms than children without ASD symptoms (5.5 vs. 4.5 yrs, U=4423; z=-2.25; p=0.025). The median age at onset of symptoms of a FDD was 3.0 years in both children with and without ASD symptoms.
Discussion This is the first prospective study assessing the prevalence of ASD symptoms in children presenting with either functional constipation or functional non-retentive fecal incontinence. In these children referred to a specialized outpatient clinic, a strikingly high prevalence of 29% of concomitant ASD symptoms was found. Of all 242 patients, 5.4% had already been diagnosed with ASD, which is remarkably higher than the prevalence of ASD in the general population. Children with ASD symptoms were older at presentation at our outpatient clinic and had experienced FDD symptoms for a longer time. There were no other clinical characteristics that significantly differed between children with and without ASD symptoms. Chapter Our results are in line with the retrospective study by Pang et al. describing a high prevalence (8.5%) of ASD diagnoses in children with FC.16 Furthermore, the current study underlines the presence of a co-occurrence of FDD and ASD as previously described in children with ASD. The prevalence of constipation in children with ASD has been reported 5 to range from 20% to 33.9% according to recent studies using parent reports or medical charts.8,9,11,24 Afzal et al. showed that fecal loading and a megarectum upon an abdominal X-ray were more common among children with ASD compared to controls (54 vs. 24%, resp.).7 Furthermore, a recent study reported that of all gastrointestinal disorders present in ASD children, constipation is the most commonly found entity (85%).10 There are several factors that could contribute to the co-occurrence of FDD and ASD (symptoms) in children. FDD and ASD are both heterogeneous disorders in which genetic factors likely play a role.5,25 The association of FDD and ASD (symptoms) could therefore be explained by the presence of contiguous gene syndromes resulting from mutations in multiple adjacent genes yet to be discovered that are associated with both disorders.26 Furthermore, FDD could be associated with atypical sensory processing, difficulties in making sense of sensory stimuli, or motor problems frequently observed in ASD and thereby disturbed gastrointestinal motility and defecation physiology.27-29 Also, it can be hypothesized that children with ASD (symptoms) ignore their urge to defecate as they can be extremely focused on other matters in their environment. FDD might as well be secondary to behavioral problems in children with (symptoms of) ASD, their resistance to change and difficulties in acquiring new skills, complicating the toilet training period which is known to be a possibly critical phase in the development of FDD.30 It has been hypothesized that a period of an inflammatory gastrointestinal process, enterocolitis, is associated with the onset of ASD. However, in a study by Sandhu
131 chapter 5 et al., there were no symptoms of enterocolitis in the early stool patterns of ASD children to support this hypothesis.31 Children with ASD often suffer from food selectivity and abnormal feeding habits have commonly been proposed to be associated with FDD in children with ASD.32 However, dietary habits could not be related to the presence of gastrointestinal problems including constipation in a recent study in ASD children.10 Lastly, FDD could be a side-effect of drugs used for the treatment of ADHD-like symptoms in ASD patients, such as Methylphenidate, Atomoxetine or Dexamphetamine. However, in this study, only five patients were recorded to use ADHD medication and in all of these patients FDD symptoms had commenced years before starting psychopharmaca. This study has several strengths. The diagnosis of FC or FNRFI in children was made according to the internationally accepted ROME III criteria by physicians highly experienced in diagnosing and treating FDD in children. Two separate validated ASD screening instruments with high sensitivity and specificity were used to prospectively assess the prevalence of ASD symptoms. In this way, a careful assessment yielded a strikingly high prevalence of ASD symptoms in children presenting with FDD. Nevertheless, there are some important points that should be taken in mind when interpreting our results and extrapolating them to other patient cohorts. Firstly, there might have been a selection bias towards more severe cases of FDD as the recruitment site was a tertiary referral center for children with FDD. This could have resulted in a higher overall prevalence of ASD symptoms as children presenting at our clinic are often difficult to treat. However, more than a third of patients had been referred directly by their GP and had never been treated before by a pediatrician or pediatric gastroenterologist. Moreover, the prevalence of ASD symptoms according to validated ASD screening instruments was similar in children only treated by a GP and children referred by a pediatrician or pediatric gastroenterologist (data not shown). Secondly, patients were not subjected to an extensive standardized assessment including direct observation and a detailed developmental history, which are mandatory to make an ASD diagnosis. However, the cut off values for the two screening instruments have been validated in the general population and have shown a good correlation with standardized instruments. Our findings may have large implications for clinical practice as well as research concerning FDD in children. In our study, ASD symptoms according to the validated screening instruments were frequently found to have been overlooked by health care professionals referring the children with FDD. We stress that professionals should be alert for ASD symptoms in children presenting with FDD as the presence of ASD symptoms may give rise to a different therapeutic approach. Apart from age at presentation and a longer duration of symptoms, we found no other clinical characteristics clearly differentiating between children with FDD with and without ASD symptoms. Standard screening of children presenting with FDD for ASD symptoms using standardized instruments which can be followed by referral for further clinical assessment in case abnormal scores are found might therefore be feasible. Future research by means of randomized controlled trials
132 Symptoms of autism spectrum disorders should further clarify whether children with FDD and co-occurring ASD symptoms would benefit from an adaptation of the current therapeutic strategy for FDD, for instance by adding specialized psycho-educational, psycho-therapeutic or psychiatric care to standard protocols. Clinical research programs on FDD should include ASD screening questionnaires in their protocols as a standard procedure as the presence of ASD symptoms might possibly influence outcomes regarding pathophysiology and treatment response. Future research should focus on unraveling the pathophysiology behind the co-occurrence of FDD and ASD symptoms. Gastrointestinal motility testing in children with FDD with and without ASD symptoms combined with functional MRI studies might lead to more insight in the possibly joint pathophysiology of FDD and ASD.
Conclusions In this study, a remarkably high prevalence of ASD symptoms was found in children presenting with FDD at a specialized outpatient clinic. Only a small subset of these children Chapter had already been diagnosed with ASD. These findings further strengthen the hypothesis of a possible association between FDD and ASD (symptoms) in children. Clinicians and researchers should be aware of ASD symptoms in children with FDD. 5 Acknowledgements The authors would like to thank the following clinicians for their help with the inclusion of patients at the outpatient clinic: R.J. van der Pol, MD, S.M. Mugie, MD, J.M.T.M. Rutten, MD, D.R. Hoekman, MD, R.E. Burgers, MD PhD, C.M. Loots, MD, B. Koot, MD, T.Z. Hummel, MD, and M.M. Tabbers, MD PhD.
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Reference list
1. Mugie SM, Benninga MA, Di LC. Epidemiology of constipation in children and adults: a systematic review. Best Pract Res Clin Gastroenterol. 2011;25:3-18. 2. Rasquin A, Di LC, Forbes D, Guiraldes E, Hyams JS, Staiano A, et al. Childhood functional gastrointestinal disorders: child/adolescent. Gastroenterology. 2006;130:1527-1537. 3. Burgers R, Benninga MA. Functional nonretentive fecal incontinence in children: a frustrating and long- lasting clinical entity. J Pediatr Gastroenterol Nutr. 2009;48 Suppl 2:S98-S100. 4. Bongers ME, van Wijk MP, Reitsma JB, Benninga MA. Long-term prognosis for childhood constipation: clinical outcomes in adulthood. Pediatrics. 2010;126:e156-e162. 5. Peeters B, Benninga MA, Hennekam RC. Childhood constipation; an overview of genetic studies and associated syndromes. Best Pract Res Clin Gastroenterol. 2011;25:73-88. 6. Van Dijk M, Benninga MA, Grootenhuis MA, Last BF. Prevalence and associated clinical characteristics of behavior problems in constipated children. Pediatrics. 2010;125:e309-e317. 7. Afzal N, Murch S, Thirrupathy K, Berger L, Fagbemi A, Heuschkel R. Constipation with acquired megarectum in children with autism. Pediatrics. 2003;112:939-942. 8. Ibrahim SH, Voigt RG, Katusic SK, Weaver AL, Barbaresi WJ. Incidence of gastrointestinal symptoms in children with autism: a population-based study. Pediatrics. 2009;124:680-686. 9. Nikolov RN, Bearss KE, Lettinga J, Erickson C, Rodowski M, Aman MG, et al. Gastrointestinal symptoms in a sample of children with pervasive developmental disorders. J Autism Dev Disord. 2009;39:405-413. 10. Gorrindo P, Williams KC, Lee EB, Walker LS, McGrew SG, Levitt P. Gastrointestinal dysfunction in autism: parental report, clinical evaluation, and associated factors. Autism Res. 2012;5:101-108. 11. Wang LW, Tancredi DJ, Thomas DW. The prevalence of gastrointestinal problems in children across the United States with autism spectrum disorders from families with multiple affected members. J Dev Behav Pediatr. 2011;32:351-360. 12. American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision. Washington, DC: American Psychiatric Publishing Inc.; 2000. 13. World Health Organization. The ICD-10 Classification of Mental and Behavioral Disorders: Diagnostic Criteria for Research. Geneva: WHO; 1993. 14. Fombonne E. Epidemiology of pervasive developmental disorders. Pediatr Res. 2009;65:591-598. 15. Autism and Developmental Disabilities Monitoring Network Surveillance Year 2008 Principal Investigators, Centers for Disease Control and Prevention. Prevalence of autism spectrum disorders--Autism and Developmental Disabilities Monitoring Network, 14 sites, United States, 2008. MMWR Surveill Summ. 2012;61:1-19. 16. Pang KH, Croaker GD. Constipation in children with autism and autistic spectrum disorder. Pediatr Surg Int. 2011;27:353-358. 17. Whitehouse AJ, Maybery M, Wray JA, Hickey M. No association between early gastrointestinal problems and autistic-like traits in the general population. Dev Med Child Neurol. 2011;53:457-462. 18. Constantino JN, Gruber CP. Social Responsiveness Scale (SRS). 2005. Western Psychological Services. 19. Roeyers H, Thys M, Druart C, De Schryver M, Schittekatte M. SRS screeningslijst voor autisme spectrum stoornissen (Social Responsiveness Scale - Screening list for ASD, manual). 2011. Amsterdam, Hogrefe Uitgevers. 20. Lord C, Rutter M, Le CA. Autism Diagnostic Interview-Revised: a revised version of a diagnostic interview for caregivers of individuals with possible pervasive developmental disorders. J Autism Dev Disord. 1994;24:659-685.
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21. Rutter M, Bailey A, Lord C. SCQ: Social Communication Questionnaire. 2003. Los Angeles, CA, Western Psychological Services. 22. Warreyn P, Raymaekers R, Roeyers H. SCQ - Vragenlijst Sociale Communicatie (Social Communication Questionnaire). 2004. Destelbergen, Belgium, SIG. 23. Vorstman JA, Morcus ME, Duijff SN, Klaassen PW, Heineman-de Boer JA, Beemer FA, et al. The 22q11.2 deletion in children: high rate of autistic disorders and early onset of psychotic symptoms. J Am Acad Child Adolesc Psychiatry. 2006;45:1104-1113. 24. Smith RA, Farnworth H, Wright B, Allgar V. Are there more bowel symptoms in children with autism compared to normal children and children with other developmental and neurological disorders?: A case control study. Autism. 2009;13:343-355. 25. Eapen V. Genetic basis of autism: is there a way forward? Curr Opin Psychiatry. 2011;24:226-236. 26. Schmickel RD. Contiguous gene syndromes: a component of recognizable syndromes. J Pediatr. 1986;109:231-241. 27. De la Marche W, Steyaert J, Noens I. Atypical sensory processing in adolescents with an autism spectrum disorder and their non-affected siblings. Research in Autism Spectrum Disorders. 2012;639-645. 28. Noens I, van Berckelaer-Onnes I. Making sense in a fragmentary world: communication in people with autism and learning disability. Autism. 2004;8:197-218. 29. Downey R, Rapport MJ. Motor activity in children with autism: a review of current literature. Pediatr Phys Ther. 2012;24:2-20. Chapter 30. Borowitz SM, Cox DJ, Tam A, Ritterband LM, Sutphen JL, Penberthy JK. Precipitants of constipation during early childhood. J Am Board Fam Pract. 2003;16:213-218. 31. Sandhu B, Steer C, Golding J, Emond A. The early stool patterns of young children with autistic spectrum disorder. Arch Dis Child. 2009;94:497-500. 5 32. Volkert VM, Vaz PC. Recent studies on feeding problems in children with autism. J Appl Behav Anal. 2010;43:155-159.
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Chapter 6
Completion of toilet training in children with defecation disorders and concomitant symptoms of autism spectrum disorders
Babette Peeters, Ilse L. Noens, Sofie Kuppens, Marc A. Benninga
Submitted chapter 6
Abstract Objective The presence of a functional defecation disorder (FDD) may delay the moment of completion of toilet training. However, the association between the presence of symptoms of autism spectrum disorders (ASD) and the moment of completion of toilet training in patients with FDD is unknown. In this study we assess the moment of completion of toilet training in children with FDD with and without concomitant symptoms of ASD and controls.
Methods Consecutive children (4 -12 yrs) presenting with FDD according to the ROME III criteria were screened for symptoms of ASD by two validated questionnaires; the Social Responsiveness Scale (SRS) and the Social Communication Questionnaire-Lifetime (SCQ-L). Children were defined as having symptoms of ASD when they scored at or above the cut-off value on one or two questionnaires (SRS≥51; SCQ≥15). Controls (4-12 yrs) were recruited from primary schools. Toilet training characteristics were compared.
Results In total, 242 children with FDD were included, of which 70 showed symptoms of ASD. The control group consisted of 96 children. Significantly less children with FDD and ASD symptoms were toilet trained for stools and urine during daytime before the age of 4 yrs (45% and 62%) than children with FDD only (60% and 76%), whereas almost all controls had completed toilet training for stools and urine during daytime before this age (95% and 98%).
Conclusion Children with FDD and ASD symptoms completed toilet training both for stools and urine during daytime at a significantly later age than children with FDD only and controls.
138 Toilet training characteristics
Introduction Functional defecation disorders (FDD), such as functional constipation and functional non-retentive fecal incontinence, are common problems in childhood that may negatively affect quality of life.(1-3) The pathophysiology of FDD is classically considered to be complex and multifactorial. Environmental, genetic, behavioral factors, and child-parent interactions have all been subject of research and seem to play a role in the etiology or persistence of symptoms.(2;4) However, the exact pathophysiology of FDD is incompletely understood. In a large proportion of children, symptoms of FDD arise in the period of toilet training.(5) Indeed, the presence of an FDD has been associated with a delayed completion of toilet training for stools and urine.(6-8) Furthermore, atypical toileting behavior, for instance stool toileting refusal and hiding away while defecating, has been associated with late completion of toilet training and the presence of constipation.(9;10) For many parents of children with FDD, difficulties in getting their child toilet trained is a major concern, as being toilet trained is one of the prerequisites for admission to most primary schools. In the literature, FDD have frequently been associated with autism spectrum disorders (ASD).(11-16) In the general population, a prevalence rate of ASD of 0.6% - 0.7% has been reported.(17) The term ‘ASD’ represents three pervasive developmental disorders as defined in the Diagnostic and Statistical Manual of Mental disorders (DSM-IV-TR): autistic disorder, Asperger syndrome and pervasive developmental disorder – not otherwise specified (PDD-NOS).(18) ASD are characterized by impairments in social interaction, Chapter in verbal and non-verbal communication, and the presence of restricted, repetitive and stereotyped patterns of behavior, interests and activities.(19) In children with ASD, toilet training problems are commonly present. For these children, toilet training has been reported to be completed at a later moment compared to controls and after being toilet 6 trained, regression in training skills often occurs due to a change in routines.(20;21) The association between the presence of concomitant symptoms of ASD and the moment of completion of toilet training in children with FDD is, however, unknown. It could be hypothesized that the presence of concomitant ASD symptoms further delays the moment of completion of toilet training in children with FDD. Identifying children with FDD and concomitant symptoms of ASD is important as these children might benefit from an early adaptation of the regular treatment strategies, for instance by adding psycho-educational, psycho-therapeutic or psychiatric care to the standard therapy for FDD. As such, the aim of this study was to compare the moment of completion of toilet training between children with FDD without ASD symptoms, children with FDD with concomitant symptoms of ASD and controls.
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Materials and Methods
Participants Between September 2009 and October 2011, consecutive patients, aged 4-12 years, referred to the outpatient clinic of a tertiary hospital in Amsterdam, The Netherlands, with a diagnosis of functional constipation (FC) or functional non-retentive fecal incontinence (FNRFI) according to the internationally accepted ROME III criteria, were included after informed consent was obtained from the parents. Patients were excluded from participation if they suffered from a known pathology causing constipation and/or fecal incontinence, such as chronic inflammatory bowel disease (Crohn’s disease or ulcerative colitis), celiac disease, or when they had a history of large bowel surgery, congenital anorectal malformations, neurological disease (complete spinal cord transection, multiple sclerosis or spina bifida) or a genetic syndrome. Furthermore, patients with a known intellectual disability and/or an intelligence quotient below 70 were excluded. Parents or caregivers filled out two validated ASD screening questionnaires about their child (Social Responsiveness Scale (SRS) and Social Communication Questionnaire – Lifetime (SCQ-L).(22;23) Children were considered to have symptoms of an ASD when they scored on or above the validated cut-off values of one or both questionnaires. For the SRS a cut-off value of ≥ 51 was used and for the SCQ-L a cut-off value of ≥ 15 was applied. (24;25) Children with FDD were divided in to two groups; one group with FDD without symptoms of ASD and another group with FDD with concomitant symptoms of ASD. This division was based on the results of the two ASD screening questionnaires. Controls, aged 4 to 12 years, were recruited from primary schools in the province of Limburg, Flanders, Belgium. Children with an FDD according to the ROME III criteria and/or an ASD diagnosis were excluded from participation. Children with a history of a diagnosis of FDD made by a medical doctor or prior or current treatment with laxatives were also excluded. The local Medical Ethics Committee waived the need for informed consent.
Children with FDD with and without symptoms of ASD During the first visit at the outpatient clinic, as part of our routine procedure, a standardized defecation questionnaire was filled out by the medical doctor. This defecation questionnaire consists of questions about the medical history of the child, social environment, medication use, moment of completion of toilet training (stools, urine during daytime and urine during nighttime) and specific questions about bowel habits and defecation pattern based on the internationally accepted ROME III criteria for functional defecation disorders.
140 Toilet training characteristics
Controls Parents of controls were informed about the study by written and verbal information. Parents of participating children were asked to fill out a bowel habit diary together with their child for a period of one week. After this week, a structured interview that included the standardized defecation questionnaire as described above was performed by telephone by a trained investigator. The presence of an FDD or ASD was ruled out by the structured interview with the parents and the interpretation of the bowel habit diary.
Outcomes The primary outcomes of this study were the moment of completion of toilet training for stools, urine during daytime, and urine during nighttime in children with FDD without symptoms of ASD, children with FDD with concomitant symptoms of ASD and controls. A child was considered toilet trained for stools, or urine during daytime when the child defecated or urinated in the toilet or potty in the majority of time for at least one month. Children, however, who had been completely toilet trained for stools but currently suffered from fecal incontinence due to FC or FNFRI were considered to be toilet trained. A child was considered to be toilet trained at night when the child had experienced nighttime bladder control for the majority of time for at least one month. The percentage of children who had completed toilet training before the age of 4 years and at the time of the study was compared between the three study groups. Furthermore, Chapter the age of completion of toilet training in children who had completed toilet training at the time of the study was compared between the three groups. Statistical Analysis 6 The statistical program SPSS version 16.0 (SPSS Inc, Chicago Ill) was used for statistical analyses. Skewed continuous data were compared between the three study groups by Kruskall-Wallis tests. To compare the proportions of children that completed toilet training between the three study groups, Fisher exact tests were performed. Effect sizes for the comparisons between the three study groups were reported as eta square (η2) in case of continuous variables and as Cramer’s V in case of dichotomous variables. Follow-up comparisons between the subgroups included Mann-Whitney U tests and Chi-square analyses. The significance level was set at <.05. P-values resulting from follow- up comparisons between the subgroups were corrected for multiple testing by Holms’ sequential Bonferroni correction.
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Results
Demographics During September 2009 and October 2011, 242 children with FDD participated in this prospective study. The majority of children with FDD suffered from FC (91%). Seventy children (29%) had symptoms of ASD according to the scores on the ASD screening questionnaires. In thirteen patients (5.4%), a diagnosis of an ASD had previously been made. Of these, one child was diagnosed with classical autism, two with Asperger Syndrome and ten with PDD-NOS. The remaining 172 patients fulfilled the criteria of FDD without having ASD symptoms. In the province of Limburg in Flanders, Belgium, parents of 909 children from primary schools were asked to participate in this study. Disappointingly, parents of only 124 children gave informed consent to participate in this study. Of these, 21 fulfilled the criteria of FC (17%) and these children were excluded. There were no children fulfilling the criteria of FNRFI. For seven of the remaining 103 children, too many data were missing to exclude a diagnosis of FDD with certainty. Those seven children were also excluded from the analyses. There were no children with a known or presumed diagnosis of an ASD as reported by the parents. This resulted in a total number of ninety-six controls that were included in the analyses. The baseline characteristics of the FDD patients without ASD symptoms, the FDD patients with concomitant ASD symptoms and general population controls are depicted in Table 1. Children with FDD and concomitant symptoms of ASD were significantly older at the time of study than children with an FDD only and general population controls;
Table 1 | Baseline characteristics of the three study groups FDD only1 FDD with ASD Controls1 Comparison of 3 symptoms1 study groups N 172 70 96 - Male 88 (51%) 43 (61%) 42 (44%) ns Median age in years 7.7 (IQR 5.5; 9.4)† 8.4 (IQR 6.6; 10.3) †* 7.2 (IQR 5.6; 9.5)* H (2, N = 338) = 5.73; p =.06; η2 = .02 Diagnosis FC without FI 43 (25%) 10 (14%) n/a n/a Diagnosis FC with FI 116 (67%) 51 (73%) n/a n/a Diagnosis FNRFI 13 (8%) 9 (13%) n/a n/a Median age start symptoms 3.0 (IQR 0.5; 4.0) 3.0 (IQR 0; 4.0) n/a n/a in years Duration of symptoms in 4.5 (IQR 2.6; 6.5) * 5.5 (IQR 3.6; 7.7) * n/a n/a years FDD = Functional Defecation Disorder ; ASD = Autism Spectrum Disorder ; IQR = Inter Quartile Range; FC = Functional Constipation ; FI = Fecal Incontinence; FNRFI = Functional Non-Retentive Fecal Incontinence ; ns = non significant ; n/a = not applicable. 1Same superscripts represent the presence of a significant difference between the subgroups based on follow-up comparisons using Holms’ sequential Bonferroni correction for multiple testing when applicable (adjusted p-values: .017; .025; .05).
142 Toilet training characteristics the median duration of FDD symptoms was significantly longer in the study group with ASD symptoms compared to the group with FDD without ASD symptoms. There were no significant differences in gender distributions between the three groups. There were also no significant differences in type of FDD diagnosis between the two groups with FDD.
Toilet trained for stools As shown in Table 2, the percentage of children that had completed toilet training for stools at the time of study was significantly higher in the control group compared to the two study groups with an FDD diagnosis. The median age at which toilet training for stools had been completed, was significantly lower in the FDD group with concomitant symptoms of ASD than in children with FDD only and controls. The percentage of children
Table 2 | Toilet training characteristics of the study groups for stools and urine FDD only1 FDD +ASD symptoms1 Controls1 Comparison of 3 (n = 172) (n = 70) (n = 96) study groups STOOLS Toilet training completed 97 (56%)* 29 (41%)* 91 (95%)* X2 (2, N = 323) before age of 4 years = 52.13; p <.001; Cramer’s V = .40 Toilet training completed at 133 (78%)* 49 (70%)† 95 (99%)*† X2 (2, N = 336) time of study = 26.26; p < .001; Cramer’s V = .28 Age at completion of toilet 3.0 (IQR 2.5; 3.5)* 3.5 (IQR 3.0; 4.0)* 3.0 (IQR 2.0; 3.0)* H (2, N = 257) = Chapter training (median) n=116 n=46 n=95 37.4; p <.001; η2 = .15 URINE DAYTIME Toilet training completed 124 (72%)* 41 (58%)* 94 (98%)* X2 (2, N = 326) before age of 4 years = 33.7; p <.001; 6 Cramer’s V = .32 Toilet training completed at 155 (90%)* 60 (86%)† 95 (99%)*† X2 (2, N = 338) time of study = 10.53; p =.005; Cramer’s V = .18 Age at completion of toilet 3.0 (IQR 2.5; 3.5)* 3.0 (IQR 3.0; 4.0)† 2.0 (IQR 2.0;3.0)*† H (2, N = 294) = training (median) n=143 n=56 n=95 40.3; p <.001; η2 = .14 URINE NIGHTTIME Toilet training completed 86 (50%)* 28 (40%)† 71 (74%)*† X2 (2, N = 327) before age of 4 years = 18.9; p <.001; Cramer’s V = .24 Toilet training completed at 127 (74%)* 50 (70%)† 89 (93%)*† X2 (2, N = 338) time of study = 15.9; p <.001; Cramer’s V = .22 Age at completion of toilet 3.4 (IQR 2.5; 4.0) 3.5 (IQR 3.0; 4.5)* 3.0 (IQR 2.0; 3.0)* H (2, N = 248) = training (median) n=112 n=47 n=89 11.3; p =.004; η2 = .05 FDD = Functional Defecation Disorder ; ASD = Autism Spectrum Disorder ; IQR = Inter Quartile Range. 1Same superscripts represent the presence of a significant difference between the subgroups based on follow-up comparisons using Holms’ sequential Bonferroni correction for multiple testing (adjusted p-values: .017; .025; .05)
143 chapter 6 who had completed toilet training for stools before the age of 4 years was the lowest in the FDD group with concomitant symptoms of ASD.
Toilet trained for urine during daytime Nearly all controls had completed toilet training for urine during the daytime at the moment of study (Table 2), which was in contrast with children with FDD with or without ASD symptoms. The median age at which toilet training for urine during daytime was achieved was not statistically different between the two FDD groups. However, a significantly higher proportion of children with FDD only had completed toilet training for urine during daytime before the age of 4 compared to children with FDD with concomitant ASD symptoms.
Toilet trained for urine during nighttime Significantly more children in the control group had completed toilet training for urine during the nighttime at the moment of study compared to the group with FDD only and the group with FDD and ASD symptoms (Table 2). No significant differences in moment of completion of toilet training for urine during nighttime existed between the FDD groups with and without symptoms of ASD (Table 2).
Discussion This is the first study comparing the moment of completion of toilet training for stools and urine between children with FDD with concomitant ASD symptoms, children with FDD only and controls. As hypothesized, a significantly lower percentage of children with FDD and concomitant ASD symptoms completed toilet training for stools and urine during daytime before the age of 4 years compared to children with FDD without ASD symptoms and controls. Becoming toilet trained is an important milestone in a child’s life and a step forward in achieving more independence. The moment of initiation and completion of toilet training depends on an individual child’s level of physical and psychological maturation, e.g. their ability to sit, walk, express their needs and to understand and respond to both their own sensations and parental instructions.(26) In the general population, the mean age at which completion of daytime toilet training for stools and urine is achieved has been reported to be 32 to 39 months.(10;27-30) Largo et al. studied completion of toilet training in a sample of almost 500 children and found that at the age of four, about 90% of both girls and boys was found to be completely toilet trained during daytime for stools and urine. In 2004, Blum et al. reported 84% of children to be completely daytime toilet trained at the age of 3.5 years and described children not being toilet trained at this age as ‘late toilet trainers’.(30) These late toilet trainers were more likely to show stool toileting refusal, to
144 Toilet training characteristics hide when defecating, to be frequently constipated and to have lower language scores at 18 months of age. In contrast with the general population and the controls in this study, we found that only 56% and 72% of the children with an FDD were toilet trained for stools and urine during daytime before the age of 4 years. An association between late completion of toilet training and the presence of FDD has been described before, although a clear explanation for this phenomenon is lacking.(6-8) Toilet refusal, which is the result of fear for the toilet in some children or can be one of the characteristics of a stubbornness in toddlers, often precedes FDD.(31) This may lead to withholding behavior with painful evacuation of hard and large stools and eventually in disturbed sensation of urge due to fecal impaction. Another hypothesis is that shame or parental punishment and pressure might be involved in problematic toilet training of children with FDD.(32) Moreover, behavioral problems might hamper typical toilet training in children with FDD.(33;34) In the group of children with FDD and concomitant symptoms of ASD, we found even lower percentages of children that had completed toilet training before the age of 4 years. In these patients, who were significantly older than the children with FDD only and controls with a median age of 8.4 years, the percentage that had completed toilet training at the time of study was only 70% for stools and 86% for urine during daytime. Children with ASD often experience difficulties in coping with changes in routines and may have specific and limited interests and behaviors. This can make it a challenge to learn children with ASD or ASD symptoms to use the potty or toilet as a new routine. A study Chapter by Dalrymple et al., describing parental views on toilet training children with ASD, showed that next to toilet training refusal, there are many problems that ASD children present with during the toilet training period.(21) Among the most commonly found were stuffing up toilets, continually flushing, playing in the toilet, refusal to use other toilets or smearing 6 feces. These behavioral factors, but also sensory, motor and cognitive factors may hinder the toilet training process. In the study by Dalrymple et al., lower cognition and lower verbal levels were significantly related to a higher age at completion of toilet training. (21) In our study, however, children with a known intellectual disability were excluded from participation. This might indicate that delayed completion of toilet training found in children with FDD and concomitant ASD symptoms in this study is not likely to be the result of their general level of cognitive functioning. Still, problems in making sense and executive dysfunction may play an important role in toilet training problems seen in children with ASD symptoms. It is known that in people with ASD, executive dysfunction, in particular a deficit in cognitive flexibility, is strongly associated with resistance to changes and the presence of restricted interests and activities.(35) One may also hypothesize that parents of children with ASD or ASD symptoms are more likely to postpone the initiation of toilet training due to the presence of other behavioral problems the parents have to cope with. Unfortunately, in this study no data were available to assess the moment of initiation of toilet training in the study groups.
145 chapter 6
Recently, the existence of a Broader Autism Phenotype was shown in fathers of children with ASD.(36) ASD symptoms were more commonly found in these fathers compared to fathers of children without ASD. The presence of ASD symptoms in one of the parents might also play a role in the success of guiding their child with ASD or ASD symptoms and FDD towards a typical toilet training status. This study has some limitations. As the site of recruitment for patients with FDD was a specialized referral center for motility disorders, there might have been a bias in the selection of patients. However, more than a third of patients have been referred directly by their GP and have never been treated before by a pediatrician or pediatric gastroenterologist for their FDD. A second limitation is that patients with FDD were screened for ASD symptoms using two validated screening instruments but were not subjected to an extensive standardized assessment including direct observation and a detailed developmental history taking, which are mandatory to make a definite diagnosis of an ASD. However, the cut-off values for the screening instruments used in this study have been validated in the general population and have shown a good correlation with standardized observation and developmental history instruments. The control group was not screened for ASD symptoms in a similar way, but it may be expected that the results from recent validation studies are a good representative for the general population. The response rate of the general control group was very low. Nevertheless, the toilet training results of this group are very similar to the results of the general population as previously published in literature. The diagnosis of FDD in the control group was based on the ROME III criteria. One of the five criteria for functional constipation in childhood is the presence of a large fecal mass in the rectum. Due to ethical objections, the presence of this criterion could not be assessed in the control group. Therefore, we might have missed some children with FDD in the control group. Lastly, it was found that a substantial amount of parents of children that had completed toilet training at the time of the study, did not remember the exact moment of completion of toilet training of their child. Therefore, the assessment of the median age at which toilet training was achieved in the subgroups is based on a small group of children. As a result, less profound differences are observed in the comparison analyses of the median ages between the groups. However, we found large differences in the comparison of the proportions of children being toilet trained before the age of 4, which is a clinically relevant and more reliable item of information as all included children were 4 years or older. Nevertheless, this study underlines that clinicians should be alert for ASD symptoms in children presenting with FDD and toilet training problems. The effect of adding specialized care to the regular treatment protocols for FDD in children with concomitant ASD symptoms should be assessed by means of randomized controlled trials. Future studies should shed more light on the sensory, motor, behavioral, and cognitive aspects of delayed toilet training in FDD children with concomitant ASD symptoms.
146 Toilet training characteristics
Conclusion Children with FDD and ASD symptoms completed toilet training for stools at a significantly later age than children with FDD only and controls. The percentage of children being toilet trained for stools or urine during daytime before the age of four was significantly lower in the FDD group with concomitant symptoms of an ASD compared to children with an FDD only or controls. Further investigations are needed to unravel the motor, sensory, behavioral, and cognitive factors that may be involved.
Chapter 6
147 chapter 6
Reference List
(1) Mugie SM, Benninga MA, Di Lorenzo C. Epidemiology of constipation in children and adults: a systematic review. Best Pract Res Clin Gastroenterol 2011;25(1):3-18. (2) Burgers R, Benninga MA. Functional nonretentive fecal incontinence in children: a frustrating and long- lasting clinical entity. J Pediatr Gastroenterol Nutr 2009;48 Suppl 2:S98-S100. (3) Bongers ME, van Wijk MP, Reitsma JB et al. Long-term prognosis for childhood constipation: clinical outcomes in adulthood. Pediatrics 2010;126(1):e156-e162. (4) Peeters B, Benninga MA, Hennekam RC. Childhood constipation; an overview of genetic studies and associated syndromes. Best Pract Res Clin Gastroenterol 2011;25(1):73-88. (5) Loening-Baucke V. Chronic constipation in children. Gastroenterology 1993;105(5):1557-64. (6) Schonwald A, Sherritt L, Stadtler A et al. Factors associated with difficult toilet training. Pediatrics 2004;113(6):1753-7. (7) Blum NJ, Taubman B, Nemeth N. Relationship between age at initiation of toilet training and duration of training: a prospective study. Pediatrics 2003;111(4 Pt 1):810-4. (8) Inan M, Aydiner CY, Tokuc B et al. Factors associated with childhood constipation. J Paediatr Child Health 2007;43(10):700-6. (9) Taubman B, Blum NJ, Nemeth N. Children who hide while defecating before they have completed toilet training: a prospective study. Arch Pediatr Adolesc Med 2003;157(12):1190-2. (10) Taubman B. Toilet training and toileting refusal for stool only: a prospective study. Pediatrics 1997;99(1):54- 8. (11) Pang KH, Croaker GD. Constipation in children with autism and autistic spectrum disorder. Pediatr Surg Int 2011;27(4):353-8. (12) Wang LW, Tancredi DJ, Thomas DW. The prevalence of gastrointestinal problems in children across the United States with autism spectrum disorders from families with multiple affected members. J Dev Behav Pediatr 2011;32(5):351-60. (13) Gorrindo P, Williams KC, Lee EB et al. Gastrointestinal dysfunction in autism: parental report, clinical evaluation, and associated factors. Autism Res 2012;5(2):101-8. (14) Nikolov RN, Bearss KE, Lettinga J et al. Gastrointestinal symptoms in a sample of children with pervasive developmental disorders. J Autism Dev Disord 2009;39(3):405-13. (15) Ibrahim SH, Voigt RG, Katusic SK et al. Incidence of gastrointestinal symptoms in children with autism: a population-based study. Pediatrics 2009;124(2):680-6. (16) Afzal N, Murch S, Thirrupathy K et al. Constipation with acquired megarectum in children with autism. Pediatrics 2003;112(4):939-42. (17) Fombonne E. Epidemiology of pervasive developmental disorders. Pediatr Res 2009;65(6):591-8. (18) World Health Organization. The ICD-10 Classification of Mental and Behavioral Disorders: Diagnostic Criteria for Research. Geneva: WHO, 1993. (19) Johnson CP, Myers SM. Identification and evaluation of children with autism spectrum disorders. Pediatrics 2007;120(5):1183-215. (20) Sandhu B, Steer C, Golding J et al. The early stool patterns of young children with autistic spectrum disorder. Arch Dis Child 2009;94(7):497-500. (21) Dalrymple NJ, Ruble LA. Toilet training and behaviors of people with autism: parent views. J Autism Dev Disord 1992;22(2):265-75. (22) Constantino, J. N. and Gruber, C. P. Social Responsiveness Scale (SRS). 2005. Western Psychological Services.
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(23) Rutter, M., Bailey, A., and Lord, C. SCQ: Social Communication Questionnaire. 2003. Los Angeles, CA, Western Psychological Services. (24) Roeyers, H., Thys, M., Druart, C., De Schryver, M., and Schittekatte, M. SRS screeningslijst voor autisme spectrum stoornissen (Social Responsiveness Scale - Screening list for ASD, manual). 2011. Amsterdam, Hogrefe Uitgevers. (25) Warreyn, P., Raymaekers, R., and Roeyers, H. SCQ - Vragenlijst Sociale Communicatie (Social Communication Questionnaire). 2004. Destelbergen, Belgium, SIG. (26) American Academy of Pediatrics. Guide to Toilet Training. Elk Grove Village, IL: 2003. (27) Wald ER, Di Lorenzo C, Cipriani L et al. Bowel habits and toilet training in a diverse population of children. J Pediatr Gastroenterol Nutr 2009;48(3):294-8. (28) Schum TR, Kolb TM, McAuliffe TL et al. Sequential acquisition of toilet-training skills: a descriptive study of gender and age differences in normal children. Pediatrics 2002;109(3):E48. (29) Schum TR, McAuliffe TL, Simms MD et al. Factors associated with toilet training in the 1990s. Ambul Pediatr 2001;1(2):79-86. (30) Blum NJ, Taubman B, Nemeth N. Why is toilet training occurring at older ages? A study of factors associated with later training. J Pediatr 2004;145(1):107-11. (31) Blum NJ, Taubman B, Nemeth N. During toilet training, constipation occurs before stool toileting refusal. Pediatrics 2004;113(6):e520-e522. (32) Fishman L, Rappaport L, Cousineau D et al. Early constipation and toilet training in children with encopresis. J Pediatr Gastroenterol Nutr 2002;34(4):385-8. (33) Van Dijk M, Benninga MA, Grootenhuis MA et al. Prevalence and associated clinical characteristics of behavior problems in constipated children. Pediatrics 2010;125(2):e309-e317. (34) Burket RC, Cox DJ, Tam AP et al. Does “stubbornness” have a role in pediatric constipation? J Dev Behav Pediatr 2006;27(2):106-11. Chapter (35) Lopez BR, Lincoln AJ, Ozonoff S et al. Examining the relationship between executive functions and restricted, repetitive symptoms of Autistic Disorder. J Autism Dev Disord 2005;35(4):445-60. (36) De la Marche W, Noens I, Luts J et al. Quantitative Autism Traits in First Degree Relatives: Evidence for the Broader Autism Phenotype in Fathers, but not in Mothers and Siblings. Autism 2011. 6
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Chapter 7
Personality, psychological distress, physical health and child rearing practices of parents of children with functional constipation
Babette Peeters, Martha A. Grootenhuis, Marieke van Dijk, Marc A. Benninga
Submitted
Parental characteristics in childhood constipation
Introduction Constipation is a common disorder in childhood with a worldwide prevalence rate up to 29.6%.1 Over 90 % of children with symptoms of constipation are considered to have a functional defecation disorder (FDD) and only in a minority an organic cause is found.2 According to the Rome III criteria for constipation, children present with infrequent painful hard stools and stool withholding behavior.3 Fecal incontinence resulting from fecal impaction is the major source of distress and embarrassment for the child and the family.4 In a large proportion of children, symptoms of FDD arise in the period of toilet training.2 Constipated children are traditionally treated by combining laxative treatment with behavioral approaches, like toilet training and education. Despite maximal appliance of current conservative treatment modalities, long term follow-up data have shown that symptoms of functional constipation persist into adulthood in 25-30% of children, negatively affecting quality of life.5,6 The pathophysiology of functional constipation is still poorly understood. Multiple factors that are thought to play a role in its etiology have been investigated in recent years, such as genetic and environmental factors and the presence of behavioral problems in constipated children.7,8 In these studies, constipated children have usually been the subject of investigation and little to no attention has been paid to the background of parents, such as their psychological and physical health, their personality and child rearing practices. In 2005, Ozokutan et al. found no significant differences in psychological characteristics between parents of 32 children with constipation and parents of 30 controls.9 However, study numbers were small and parents of children with fecal incontinence were excluded from the study, while it is known that the presence of fecal incontinence is associated with a certain level of parental distress.4 In 2009, an Iranian study showed that personality dimensions of mothers of 150 children with functional constipation differed from mothers Chapter of 150 controls.10 Mothers of constipated children were found to have higher scores on personality dimensions as extraversion, conscientiousness and agreeableness. Up till now, no studies have systematically investigated physical health and child rearing practices of mothers of constipated children and most data are lacking with respect to 7 fathers of constipated children. Identification of certain personality patterns, levels of psychological distress, specific health problems and child rearing practices in mothers and fathers of constipated children might lead to an adaptation of the current treatment strategy for children with refractory functional constipation towards a more systemic approach including the parents. Furthermore, it may provide more insight in the complex pathophysiology of functional constipation and/or its consequences. Therefore, in the present study, we compared the abovementioned characteristics between parents of children with functional constipation and parents of controls.
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Methods
Study design This was an explorative cross-sectional cohort study carried out in the Netherlands.
Study population Between January 2010 and August 2012, parents of consecutive patients, aged 4-16 years, presenting at the outpatient clinic of a tertiary hospital in Amsterdam, The Netherlands, with a diagnosis of functional constipation (FC) according to the internationally accepted ROME III criteria, were included in this study. Participating parents were asked to recruit parents of another child from their own environment, age comparable to the age of their own child, without functional constipation and without other chronic disorders to serve as their own controls. Parents were excluded from participation if their knowledge of the Dutch language was insufficient to fill out the questionnaires. In total, 170 mothers and 170 fathers of 170 children with functional constipation gave informed consent to participate of which a total of 116 mothers and 115 fathers of 127 children with functional constipation completed the study (response rate 68%). In the control group, 104 mothers and 104 fathers of 104 children gave informed consent to participate of which a total of 84 mothers and 72 fathers of 91 children completed the study (response rate 75%). No parents were excluded based on the exclusion criteria. The local Medical Ethics Committee waived the need for informed consent.
Procedures Control parents were asked for signs of constipation and the presence of other chronic disorders in their child by one of the investigators before participation. After considered eligible for participation and after informed consent, both mothers and fathers from the two study groups were requested to fill out several questionnaires at home in an online secured testing-environment on the internet. Personal codes and passwords were provided by email.
Questionnaires Demographics This questionnaire was composed by the investigators and consisted of several questions regarding general information about sex and age, ethnicity, marital status, and educational level.
Personality dimensions - NEO-Five Factor Inventory (NEO-FFI) Personality dimensions were evaluated by the Dutch version of the NEO-FFI which is a validated and shortened questionnaire based on the NEO-Personality Inventory. The
154 Parental characteristics in childhood constipation
NEO-FFI has demonstrated to have a good internal consistency and test-retest reliability.11 It provides a concise measure of the five basic personality factors; Neuroticism, Extraversion, Openness to experience, Agreeableness and Conscientiousness by 60 items that are scored on a 5-point Likert scale.11,12 Next to raw domain scores, sex- and age-dependent norm scores for the general population can also be calculated. In this study, the NEO-FFI had an acceptable internal consistency (Cronbach’s alpha 0.7). Subscale consistencies varied from 0.7 to 0.9.
Psychological distress and symptoms - Brief Symptom Inventory (BSI) The BSI is a short self-report questionnaire, adapted from the longer Symptom Check List – 90 (SCL-90), and provides an overview of current (past seven days) psychological distress and symptoms on several subscales: Somatization, Obsessive-compulsive, Interpersonal sensitivity, Depression, Anxiety, Hostility, Phobic anxiety, Paranoid ideation and Psychoticism.13 Psychometric properties of the BSI have been demonstrated to be good. Symptoms are scored on a 5-point Likert scale ranging from ‘0 = not at all’ to ‘4 = extremely’. Higher scores indicate more severe complaints. A total score, which is an average rating of all 53 items, can be calculated as an overall indication of psychological functioning. Sex-specific norm scores derived from the general Dutch population are available.14 The internal consistency of the BSI in this study was found to be excellent (Cronbach’s alpha > 0.9). Subscale consistencies varied from 0.6 to 0.8.
- Physical health – Physical Symptom Checklist (PSC) The PSC quantifies the number of reported physical symptoms in the preceding week.15 The checklist consists of 51 non-gender specific physical symptoms mentioned in the DSM-III classification and includes a broad array of symptoms covering most organ systems.16 Symptoms are rated on a severity scale of 0 to 3, and symptoms are considered to be Chapter present when scored 2 or 3 (bothersome often or most of the time during the previous week). Gender specific average scores are available for the Dutch general population with and without anxiety or depression. Items can also be divided in to different organ system categories: general/neurological (11 items), autonomic (10 items), musculoskeletal/pain 7 (8 items), gastrointestinal (13 items), urological/genital (5 items) and feeling hot/cold (4 items). In this study, the internal consistency of the PSC was excellent (Cronbach’s alpha > 0.9). Subscale consistencies varied from 0.6 to 0.8.
- Child Rearing Practices – Ghent Parental Behavior Scale (GPBS) The GPBS was developed to provide insight in concrete parental behavior rather than child rearing attributions.17 A total of 58 items are scored on a 5-point Likert scale and examine nine parenting subscales: Discipline, Ignoring of Unwanted Behavior, Harsh Punishment, Positive Parental Behavior, Teaching Rules, Autonomy, Monitoring, Material Rewarding,
155 chapter 7 and Inconsistent Discipline. In this study, the self-report form for parents rating their own parenting behavior was used. Sex specific norm scores for the general population are available.18 Psychometric properties of the GPBS have reported to be sufficient to good. In this study, the internal consistency of the GPBS was good (Cronbach’s alpha 0.8). Subscale consistencies varied from 0.6 to 0.9.
Outcome measures The main outcome measures of this study are the differences in baseline characteristics, personality dimensions, psychological distress, physical health and parenting behavior between parents of children with childhood constipation and parents of controls.
Statistical analysis The statistical program SPSS version 16.0 (SPSS Inc, Chicago Ill) was used for statistical analyses. Normally distributed data are reported as mean with standard deviations and compared between groups by independent t-tests. Skewed continuous data are reported as medians with inter quartile ranges and compared between groups by Mann-Whitney U analyses. To compare proportions of parents with scores above certain cut-off points between groups, Chi-square analyses or Fisher Exact tests were performed. The significance level was set at p<0.01 to correct for multiple testing between the study groups. However, due to the explorative character of the study, differences with p-values<0.05 were reported as trends.
Results
Baseline characteristics and demographics of the participants Baseline characteristics of participating parents and their children are depicted in Table 1. In total, 116 mothers and 115 fathers of 127 children with functional constipation and 84 mothers and 73 fathers of 91 controls participated in this study. Parents of children with functional constipation were more frequently found to be divorced or separated from the other parent compared to parents of controls (20% vs. 7% resp, X2 7.61, p=0.006). There was a significant difference in parental educational level between the two study groups. Controls more often had at least one parent with an academic degree compared to children with functional constipation (36% vs. 18% resp, X2 9.15, p=0.002).
Parents of constipated children and parents of controls For both parents of children with functional constipation and parents of controls, raw scores and norm scores on the questionnaires can be found in Table 2. The most salient findings are discussed below.
156 Parental characteristics in childhood constipation
Table 1 | Baseline characteristics of children and their participating parents Children with functional Control children constipation N 127 91 Boys 70 (55%) 54 (56%) Mean age child in years (sd) 9.4 (±3.6) 9.1 (±3.3) Number of participating parents 231 157 - both mother and father 104/127 (82%) 66/91 (73%) - only mother 12/127 (9%)* 18/91 (20%) - only father 11/127 (9%) 7/91 (8%) Children with divorced/separated parents 25/127 (20%)† 6/91 (7%) Highest education parents - primary school 0/127 (0%) 1/91 (1%) - secondary school 17/127 (13%) 11/91 (12%) - vocational education 81/127 (64%) 46/91 (51%) - university 23/127 (18%)† 33/91 (36%) - other 6/127 (5%) 1/91 (1%) Having an unemployed parent 23/127 (18%) 12/91 (13%) Male parents 115/231 (50%) 73/157 (47%) Caucasian 220/231 (95%) 150/157 (96%) Mean age parents 41.6 (±6.3) 40.7 (±6.0) * = difference p<0.05 between the constipation and control group † = difference p<0.01 between the constipation and control group
- Personality Parents of children with functional constipation had significantly higher raw scores on the subscale Neuroticism of the NEO-FFI compared to parents of controls. Sex dependent and Chapter age dependent norm scores were also significantly higher for Neuroticism in parents of constipated children.
- Psychological distress 7 Higher median raw scores were found in parents of constipated children compared to parents of controls on the dimensions Somatization, Depression, Anxiety, Phobic Anxiety and Overall score of the BSI. When correcting for gender while applying the norm scores from the general population, median norm scores on Somatization, Interpersonal sensitivity, Depression, Anxiety, Phobic Anxiety and Overall scores were found to be significantly higher in parents of children with functional constipation.
- Physical symptoms A significantly lower median number of physical complaints on the PSC was demonstrated in parents of controls compared to parents of children with functional constipation. There
157 chapter 7 was a large difference in the proportion of parents scoring above the 75th percentile of norm scores derived from the general population between the groups. Parents of constipated children had higher total scores on each organ system subscale except from musculoskeletal symptoms. However, they did not report constipation significantly more frequently than did parents of controls (2.6% vs. 0.6%, p=0.249, data not shown).
- Child rearing practices On the GPBS, significantly higher raw mean scores were found on the domain of Discipline for parents of constipated children compared to parents of controls. After applying sex specific norm scores, the domains of Positive parenting behavior and Material Rewarding were found to be significantly stronger expressed in parents in the functional constipation group.
Mothers of constipated children and mothers of controls Characteristics of mothers of children with functional constipation and mothers of controls can be found in Table 2.
Table 2 | Differences between parents of constipated children and parents of controls PARENTS CONSTIPATED CHILDREN PARENTS CONTROLS Total Mothers Fathers Total Mothers Fathers n=231 n=116 n=115 n=157 n=84 n=73 Male 115/231 (50%) - - 73/157 (47%) - - Mean age 41.6 (±6.3) 40.2 (±5.8) 43.1 (±6.1) 40.7 (±6.0) 40.0 (±5.8) 41.5 (±6.1) Caucasian 220/231 (95%) 111 (95.7%) 109 (94.8%) 150/157 (96%) 77 (91.7%) 73 (100%) Unemployed 25/231 (11%) 19 (16.3%) 6 (5.2%) 12/157 (8%) 8 (9.5%) 4 (5.5%) NEO-FFI Raw scores (mean (sd)) Neuroticism 29.6 (8.2) † 31.1 (8.1) * 28.8 (8.1) 27.9 (6.1) 28.2 (6.3) 27.6 (5.9) Extraversion 42.6 (6.2) 42.7 (5.8) 42.4 (6.5) 42.9 (5.1) 43.1 (5.4) 42.7 (4.8) Openness to 35.6 (5.9) 36.0 (5.6) 35.2 (6.2) 36.6 (6.5) 37.0 (6.0) 36.3 (7.0) experience Agreeableness 45.5 (5.2) 47.0 (4.6) 44.0 (5.3) 45.2 (5.2) 47.3 (3.9) 42.9 (5.5) Conscientiousness 46.8 (5.6) 47.1 (5.1) 46.9 (6.2) 46.5 (4.9) 46.5 (4.6) 46.5 (5.2) Sex dependent norm scores (mean (sd)) Neuroticism 4.7 (2.0) † 4.8 (2.0) † 4.6 (2.0) 4.3 (1.6) 4.1 (1.6) 4.6 (1.5) Extraversion 5.7 (1.9) 5.7 (1.8) 5.8 (2.1) 5.8 (1.6) 5.8 (1.7) 5.9 (1.5) Openness to 5.0 (1.8) 4.9 (1.8) 5.0 (1.9) 5.2 (1.9) 5.1 (1.8) 5.3 (2.1) experience Agreeableness 5.7 (1.9) 5.8 (1.8) 5.6 (1.9) 5.6 (1.8) 5.9 (1.5) 5.2 (2.1) Conscientiousness 5.5 (2.0) 5.6 (1.9) 5.4 (2.1) 5.4 (1.8) 5.5 (1.8) 5.3 (1.8)
158 Parental characteristics in childhood constipation
Table 2 | Differences between parents of constipated children and parents of controls (cont.) PARENTS CONSTIPATED CHILDREN PARENTS CONTROLS Total Mothers Fathers Total Mothers Fathers n=231 n=116 n=115 n=157 n=84 n=73 Age dependent norm scores (mean (sd)) Neuroticism 4.6 (1.9) † 5.0 (1.9) * 4.3 (2.0) 4.3 (1.6) 4.3 (1.6) 4.2 (1.5) Extraversion 5.5 (1.9) 5.5 (1.8) 5.5 (2.0) 5.5 (1.6) 5.5 (1.6) 5.5 (1.5) Openness to 4.7 (1.9) 4.8 (1.8) 4.6 (2.0) 4.9 (2.0) 5.0 (1.7) 4.8 (2.2) experience Agreeableness 5.3 (1.9) 5.9 (1.8) 4.8 (1.9) 5.2 (1.8) 5.9 (1.5) 4.4 (1.9) Conscientiousness 5.5 (2.0) 5.5 (1.9) 5.4 (2.2) 5.3 (1.8) 5.3 (1.8) 5.3 (1.9) BRIEF SYMPTOM INVENTORY (BSI) Raw scores (median (IQR)) Somatization 0.14 (0-0.3) * 0.14 (0-0.43) 0.0 (0-0.2) * 0.0 (0-0.14) 0.0 (0-0.3) 0.0 (0-0.1) Obsessive- 0.17 (0-0.5) 0.21 (0-0.5) 0.17 (0-0.5) 0.17 (0-0.5) 0.17 (0-0.5) 0.17 (0-0.5) compulsive Interpersonal 0.25 (0-0.5) 0.25 (0-0.75) 0.25 (0-0.5) 0.25 (0-0.5) 0.25 (0-0.5) 0.25 (0-0.5) sensitivity Depression 0.0 (0-0.5) * 0.17 (0-0.5) * 0 (0-0.5) 0.0 (0-0.33) 0.0 (0-0.3) 0 (0-0.3) Anxiety 0.17 (0-0.3) † 0.17 (0-0.5) * 0 (0-0.3) 0.17 (0-0.33) 0.17 (0-0.3) 0.17 (0-0.3) Hostility 0.2 (0-0.4) 0.2 (0.2-0.4) * 0.2 (0-0.4) 0.2 (0-0.4) 0.2 (0.2-0.4) 0.2 (0-0.4) Phobic Anxiety 0.0 (0-0.2) † 0.0 (0-0.2) 0.0 (0-0.2) 0.0 (0-0.2) 0.0 (0-0.2) 0.0 (0-0.0) Paranoid ideation 0.2 (0-0.4) 0.2 (0.2-0.6) 0.2 (0-0.4) 0.2 (0-0.4) 0.2 (0-0.4) 0.2 (0-0.6) Psychoticism 0.0 (0-0.2) 0.0 (0-0.4) 0.0 (0-0.2) 0.0 (0-0.2) 0.0 (0-0.4) 0.0 (0-0.2) Overall score 0.17 (0.1-0.4) * 0.19 (0.1-0.4) * 0.17 (0.1-0.3) 0.15 (0-0.29) 0.15 (0.1-0.3) 0.15 (0.1-0.3) Sex specific norm scores (median (IQR)) Somatization 4 (4-5) † 4 (3-5) * 4 (4-6) * 4 (3-4) 3 (3-4) 4 (4-5) Obsessive- 3 (3-4) 4 (3-4) 3 (3-5) 3 (3-4) 3 (3-4) 3 (3-5) Chapter compulsive Interpersonal 4 (3-5) * 4 (3-5) 4 (3-5) 4 (3-4) 4(3-4) 3 (3-4) sensitivity Depression 4 (3-5) † 3 (3-5)† 4 (4-5) 4 (3-4.5) 3 (3-4) 4 (4-5) Anxiety 3 (3-5) † 3 (3-5) 3 (3-5) 3 (3-4) 3 (3-4) 3 (3-3) 7 Hostility 4 (4-5) * 4 (4-5) 4 (3-5) 4 (4-5) 4 (4-5) 4 (4-5) Phobic Anxiety 4 (4-5) 4 (4-5) 4 (4-5) * 4 (4-5) 4 (4-5) 4 (4-4) Paranoid ideation 4 (3-5) 4 (3-5) 4 (3-5) 4 (3-4) 4 (3-4) 4 (3-5) Psychoticism 4 (4-5) 4 (4-5) 4 (4-4) 4 (4-5) 4 (4-5) 4 (4-4) Overall score 3 (2-5) * 3 (2-5) * 3 (2-5) 3 (2-4) 3 (2-4) 3 (2-5) PHYSICAL SYMPTOM CHECKLIST (PSC) Raw scores (median (IQR)) PSC score* 1 (0-3) † 1 (0-4) † 0.9 (0-2) † 0 (0-1) 0 (0-1) 0 (0-1) % > sex specific cut- 65 (28%) † 34 (29%) * 31 (27%) 24 (15%) 12 (14%) 12 (16%) off score for general population (>p75)*
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Table 2 | Differences between parents of constipated children and parents of controls (cont.) PARENTS CONSTIPATED CHILDREN PARENTS CONTROLS Total Mothers Fathers Total Mothers Fathers n=231 n=116 n=115 n=157 n=84 n=73 Number of symptoms on subscale (median (IQR)) Autonomic 0 (0-0) † 0 (0-0) † 0 (0-0) * 0 (0-0) 0 (0-0) 0 (0-0) Neurological 0 (0-1) † 0 (0-1.8) † 0 (0-0) 0 (0-0) 0 (0-0) 0 (0-0) Musculoskeletal 0 (0-1) 0 (0-1) * 0 (0-0) 0 (0-0) 0 (0-0) 0 (0-0) Gastrointestinal 0 (0-1) † 0 (0-1) † 0 (0-0) * 0 (0-0) 0 (0-0) 0 (0-0) Warm/cold/ 0 (0-0) † 0 (0-0) * 0 (0-0) 0 (0-0) 0 (0-0) 0 (0-0) urogenital GHENT PARENTAL BEHAVIOR SCALE (GPBS) Raw scores (mean (sd)) Autonomy 11.3 (2.0) 11.4 (2.0) 11.2 (2.1) 11.5 (1.7) 11.6 (1.7) 11.5 (1.6) Discipline 18.0 (5.0)* 18.4 (5.3)* 17.7 (4.5) 16.9 (3.8) 16.9 (3.5) 16.9 (4.2) Positive parental 45.2 (7.6) 47.2 (7.5) 43.2 (7.1) 45.1 (5.6) 46.1 (5.5) 44.0 (5.4) behavior Harsh punishment 4.6 (1.8) 4.5 (1.9) 4.7 (1.7) 4.6 (1.5) 4.7 (1.8) 4.5 (0.9) Monitoring 15.0 (5.1) 16.8 (5.2) 13.4 (4.4) 15.1 (4.6) 15.9 (4.7) 14.2 (4.3) Teaching rules 25.4 (4.1) 26.0 (4.2) 24.9 (3.9) 25.2 (3.5) 25.8 (3.3) 24.6 (3.7) Ignoring of 6.8 (2.5) 6.5 (2.2) 7.1 (2.7) 6.9 (2.6) 6.6 (2.5) 7.2 (2.6) unwanted behavior Material rewarding 7.9 (1.9) 7.6 (1.9) 8.1 (1.9) 7.5 (2.3) 7.4 (2.0) 7.5 (2.1) Inconsistent 8.0 (2.5) 7.7 (2.4) 8.2 (2.5) 8.0 (2.3) 7.9 (2.4) 8.2 (2.2) discipline Sex specific norm scores (mean (sd)) Autonomy 3.0 (0.9) 3.1 (0.9) 3.0 (0.9) 3.2 (0.8) 3.2 (0.8) 3.2 (0.7) Discipline 3.2 (0.7) 3.2 (0.7) 3.3 (0.7) 3.1 (0.7) 3.0 (0.7) 3.2 (0.8) Positive parental 3.4 (0.9)* 3.4 (0.8) † 3.3 (0.8) 3.2 (0.8) 3.1 (0.8) 3.3 (0.8) behavior Harsh punishment 2.3 (0.7) 2.2 (0.6) 2.4 (0.8) 2.3 (0.7) 2.4 (0.8) 2.3 (0.5) Monitoring 2.8 (1.0) 2.8 (1.1) 2.7 (0.8) 2.8 (0.9) 2.8 (1.0) 2.8 (0.8) Teaching rules 2.7 (1.2) 2.6 (1.3) 2.7 (1.1) 2.5 (1.1) 2.3 (1.2) 2.6 (1.0) Ignoring of 2.7 (0.8) 2.8 (0.5) 2.6 (1.0) 2.8 (0.7) 2.9 (0.6) 2.7 (0.9) unwanted behavior Material rewarding 3.1 (0.7)* 3.0 (0.7) 3.2 (0.7) 3.0 (0.8) 2.9 (0.8) 3.0 (0.8) Inconsistent 2.8 (1.0) 2.7 (0.9) 2.8 (1.0) 2.8 (0.9) 2.8 (0.8) 2.8 (0.9) discipline * = difference p<0.05 between the constipation and control group † = difference p<0.01 between the constipation and control group IQR = Inter Quartile Range
160 Parental characteristics in childhood constipation
- Baseline characteristics There were no statistically significant differences between the two groups of mothers with regard to baseline characteristics. Mothers of constipated children were more frequently unemployed than were mothers of controls, but this difference was not statistically significant.
- Personality On the NEO-FFI, mothers of constipated children showed higher raw scores as well as higher sex- and age specific norm scores for Neuroticism compared to mothers of controls. For other personality domains, differences were not statistically significant between the groups.
- Psychological distress Raw scores on the BSI-subscales Depression, Anxiety, Hostility and the BSI Overall score were found to be higher in mothers of constipated children. Lower sex specific norm scores were found on the subscales Somatization, Depression and Overall score in mothers of controls.
- Physical symptoms More bothersome physical complaints were present according to the PSC questionnaire in mothers of constipated children compared to mothers of controls. On all subscales of complaints, median scores of mothers having a child with functional constipation exceeded the scores of mothers of controls.
- Child rearing practices Concerning parenting behavior, mothers of children with functional constipation scored Chapter remarkably higher on the domain of Discipline on the GPBS compared to mothers of controls. However, sex specific norm scores were only significantly different between the two groups of mothers on the domain of Positive parental behavior, with mothers of constipated children having higher mean norm scores. 7
Fathers of constipated children and fathers of controls In Table 2, characteristics of fathers of children with functional constipation and fathers of controls are provided. There were no statistically significant differences between the two groups of fathers in baseline characteristics and personality according to the NEO-FFI.
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- Psychological distress The median raw score on the BSI-subscale Somatization was different between the two groups of fathers. Lower sex specific norm scores were found in fathers of controls on the subscales Somatization and Fobic Anxiety.
- Physical symptoms The median number of bothersome physical symptoms according to the PSC questionnaire was higher in fathers of constipated children compared to fathers of controls. Fathers having constipated children scored higher on the subscale of Autonomic symptoms and Gastrointestinal symptoms.
- Child rearing practices No significant differences were found between the study groups concerning parenting behavior according to the GPBS.
Discussion In this study, we systematically explored personality characteristics, psychological distress, physical complaints and parenting behavior of parents of children with functional constipation and parents of controls. Parents of children with functional constipation tended to score higher on neuroticism with regard to personality, experienced more psychological distress (mainly somatization, anxiety and depression) and reported more bothersome physical complaints. Differences in parenting behavior were found to be small. Parents of children with constipation were more frequently found to be divorced or to be living separately from the other parent, than were parents of controls. When characteristics of mothers and fathers were separately compared between the groups, it was found that most differences found between the parents could be attributed to differences between the mothers. Previous studies conducted in parents of constipated children have shown different results. In contrast to our study, Ozukutan et al. found no differences in psychological distress levels in parents of constipated children compared to parents of controls.9 This study excluded however parents of children with fecal incontinence, which is known to be an important stressor in families of constipated children.4 Farnam et al. indeed found differences in personality characteristics of Iranian mothers of children with constipation compared to mothers of controls, but in contrary to our results, mothers of constipated children scored lower on Neuroticism compared to mothers of controls.10 Instead, they demonstrated higher scores on the personality domains Extraversion, Conscientiousness and Agreeableness. We were not able to find an explanation for this difference.
162 Parental characteristics in childhood constipation
More similarities, however, can be found with data from mothers of children with functional abdominal pain. Campo et al. described mothers of children with functional abdominal pain reporting more somatic complaints than mothers of controls.19 Furthermore, anxiety and depression were more common among these mothers, in line with our results in parents (namely mothers) of constipated children. Unfortunately, data on this subject concerning fathers of children with functional abdominal pain are lacking. It remains uncertain how to explain the differences that were found in our study with respect to etiology. One could hypothesize that the identified differences in parental characteristics may be a consequence of having a child with functional constipation. In psychiatry, family accommodation is a well-known phenomenon which is described as the ways in which family members, especially parents, change their behavior so as to help a relative to diminish or avoid distress caused by a disorder.20 Next to this, the burden of having a child with functional constipation, which frequently goes along with the presence of fecal incontinence, abdominal pain and frequent school absenteeism, might have led to psychological distress and somatization. Children with constipation use more health services, which could have made parents more alert for physical complaints themselves.21 Furthermore, children with functional constipation frequently display behavioral problems which may have an influence on parental wellbeing.8,22 On the other hand, next to genetic and other environmental influences, the presence or persistence of functional constipation in children could be a consequence of specific parenting behavior, health and/or personality or the experience of stressful life events. It has been shown that children of parents with somatic complaints report greater health and somatic complaints than children of healthy or organically ill parents.23-25 Next to this, psychological distress in parents can have a vast influence on their children. For example, it has been found that the presence of depressive symptoms in parents is related to school absenteeism and increased health care use in their children.26 Furthermore, the Chapter increased levels of anxiety found in parents of constipated children in this study may have contributed to the development and persistence of complaints. Up to 60% of anxious parents have children with an anxiety disorder.27 Anxiety is believed to contribute to the development and course of constipation due the reinforcement of withholding behavior 7 leading to increased pelvic floor tension.3,28 Studies on neuroticism in nonclinical samples have generally demonstrated that higher levels of maternal neuroticism are related to higher levels of irritability and criticism which may affect child-parent interaction.29 It is remarkable that most differences found in our study could be attributed to mothers. In 1993, it was demonstrated in a community sample of preschool children, that fathers were significantly less involved in childrearing than mothers, but viewed themselves as more involved than their wives viewed them.30 Although this phenomenon currently takes a change, mothers in general still tend to spend more time with their children as fathers are commonly the wage-earners. Especially mothers of chronically ill children tend to work less hours a week than mothers of healthy children.31 Hereby, mothers are primarily facing
163 chapter 7 the daily hassles going along with constipation in their child and this might explain the fact that most differences were demonstrated between the mothers of the study groups. We have found less profound differences in parenting behavior between the two study groups than expected. However, a recent study showed that parental beliefs about fecal incontinence due to constipation change with consultation of a medical professional.32 Before consultation of a professional, feelings of blame and punishment were frequently found in parents towards their constipated children, whereas after education these levels decreased. Parents of children with constipation participating in our study already consulted a medical professional, which could have resulted in adapted parenting behavior. Several limitations should be taken in mind when interpreting the results of our study and extrapolating them to other patient groups. There might have been a bias in our study population towards more severe cases as parents of constipated children were included in a tertiary referral center for functional defecation disorders. However, nearly a third of all patients were directly referred by a general practitioner without consultation of a general pediatrician. The proportion of parents having an academic degree was higher in the control group despite the fact that parents of patients recruited their own controls. Still, the control group appeared to be a reasonable representative for the general population as their scores were largely comparable to the norm scores of the questionnaires. Our study can not answer the question of cause and effect. Still, the demonstrated differences between parents, and especially mothers, of constipated children and controls are important to keep in mind when evaluating and treating children with functional constipation. As the cornerstones of the treatment of childhood functional constipation are based on providing structure in toileting by regular toilet sits, neglecting fecal incontinence and praising positive defecation behavior, the presence of certain parental characteristics might hamper a successful treatment. Therefore, in case of children with functional constipation refractory to intensive medical treatment, parental factors possibly affecting the treatment should be evaluated and a more family-based multidisciplinary treatment strategy should be considered. Future research should focus on longitudinal prospective studies in order to answer the most important question of cause and effect in this light.
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Reference List
1. Mugie SM, Benninga MA, Di LC. Epidemiology of constipation in children and adults: a systematic review. Best Pract Res Clin Gastroenterol. 2011;25:3-18. 2. Loening-Baucke V. Chronic constipation in children. Gastroenterology. 1993;105:1557-1564. 3. Rasquin A, Di LC, Forbes D, Guiraldes E, Hyams JS, Staiano A, et al. Childhood functional gastrointestinal disorders: child/adolescent. Gastroenterology. 2006;130:1527-1537. 4. Kaugars AS, Silverman A, Kinservik M, Heinze S, Reinemann L, Sander M, et al. Families’ perspectives on the effect of constipation and fecal incontinence on quality of life. J Pediatr Gastroenterol Nutr. 2010;51:747- 752. 5. Bongers ME, van Wijk MP, Reitsma JB, Benninga MA. Long-term prognosis for childhood constipation: clinical outcomes in adulthood. Pediatrics. 2010;126:e156-e162. 6. Bongers ME, Benninga MA, Maurice-Stam H, Grootenhuis MA. Health-related quality of life in young adults with symptoms of constipation continuing from childhood into adulthood. Health Qual Life Outcomes. 2009;7:20. 7. Peeters B, Benninga MA, Hennekam RC. Childhood constipation; an overview of genetic studies and associated syndromes. Best Pract Res Clin Gastroenterol. 2011;25:73-88. 8. Van Dijk M, Benninga MA, Grootenhuis MA, Last BF. Prevalence and associated clinical characteristics of behavior problems in constipated children. Pediatrics. 2010;125:e309-e317. 9. Ozokutan BH, Zoroglu S, Ceylan H, Ozkan KU. Psychological evaluation of children with idiopathic constipation and their parents. Pediatr Int. 2005;47:311-315. 10. Farnam A, Rafeey M, Farhang S, Khodjastejafari S. Functional constipation in children: does maternal personality matter? Ital J Pediatr. 2009;35:25. 11. Costa PT, McCrae RR. Revised NEO Personality Inventory (NEO-PR-I) and the Five Factor Inventory (NEO-FFI): professional manual. Odessa, FL: Psychological Assessment Resources; 1992. 12. Hoekstra HA, Ormel J, De Fruyt F. Manual of the Dutch version of the NEO-PI-R/NEO-FFI. Lisse, The Netherlands: Swets and Zeitlinger; 1996. 13. Derogatis LR, Melisaratos N. The Brief Symptom Inventory: an introductory report. Psychol Med. 1983;13:595-605. Chapter 14. De Beurs E. Brief Symptom Inventory, Manual, Addendum. Leiden, The Netherlands: Pits BV; 2009. 15. Van Hemert AM. Physical Symptom Checklist. Leiden, The Netherlands: Leiden University Medical Center; 2003. 16. American Psychiatric Association. Diagnostic and statistical manual of mental disorders, third edn. Washington, DC: APA; 1980. 7 17. Van Leeuwen KG, Vermulst AA. Some psychometric properties of the Ghent Parental Behavior Scale. Eur J Psychol Assess. 2004;20:283-298. 18. Van Leeuwen KG. The Ghent Parental Behavior Scale, Manual. Belgium: University of Ghent; 2002. 19. Campo JV, Bridge J, Lucas A, Savorelli S, Walker L, Di LC, et al. Physical and emotional health of mothers of youth with functional abdominal pain. Arch Pediatr Adolesc Med. 2007;161:131-137. 20. Calvocoressi L, Lewis B, Harris M, Trufan SJ, Goodman WK, McDougle CJ, et al. Family accommodation in obsessive-compulsive disorder. Am J Psychiatry. 1995;152:441-443. 21. Liem O, Harman J, Benninga M, Kelleher K, Mousa H, Di LC. Health utilization and cost impact of childhood constipation in the United States. J Pediatr. 2009;154:258-262. 22. Burket RC, Cox DJ, Tam AP, Ritterband L, Borowitz S, Sutphen J, et al. Does “stubbornness” have a role in pediatric constipation? J Dev Behav Pediatr. 2006;27:106-111.
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23. Craig TK, Cox AD, Klein K. Intergenerational transmission of somatization behaviour: a study of chronic somatizers and their children. Psychol Med. 2002;32:805-816. 24. Walker LS, Greene JW. Children with recurrent abdominal pain and their parents: more somatic complaints, anxiety, and depression than other patient families? J Pediatr Psychol. 1989;14:231-243. 25. Walker LS, Garber J, Greene JW. Somatic complaints in pediatric patients: a prospective study of the role of negative life events, child social and academic competence, and parental somatic symptoms. J Consult Clin Psychol. 1994;62:1213-1221. 26. Guevara JP, Mandell D, Danagoulian S, Reyner J, Pati S. Parental Depressive Symptoms and Children’s School Attendance and Emergency Department Use: A Nationally Representative Study. Matern Child Health J. 2012. 27. Ginsburg GS, Schlossberg MC. Family-based treatment of childhood anxiety disorders. Int Rev Psychiat. 2002;14:143-154. 28. Whitehead WE. Psychosocial aspects of functional gastrointestinal disorders. Gastroenterol Clin North Am. 1996;25:21-34. 29. Bornstein MH, Hahn CS, Haynes OM. Maternal personality, parenting cognitions, and parenting practices. Dev Psychol. 2011;47:658-675. 30. McBride BA, Mills G. A comparison of mother and father involvement with their preschool age children. Early Child Res Quart. 1993;8:547-477. 31. Hatzmann J. Consequences of care: Parents of children with a chronic disease. Amsterdam, The Netherlands: University of Amsterdam; 2009. 32. van Tilburg MA, Squires M, Blois-Martin N, Williams C, Benninga MA, Peeters B, et al. Parental knowledge of fecal incontinence in children. J Pediatr Gastroenterol Nutr. 2012;55:283-287.
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Sacral neuromodulation therapy: a promising treatment for adolescents with refractory functional constipation
Bart P. van Wunnik, Babette Peeters, Bas Govaert, Fred H. Nieman, Marc A. Benninga, Cor G Baeten
Dis Colon Rectum 2012; 55(3):278-85 chapter 8
Abstract Background: Sacral neuromodulation therapy has been successfully applied in adult patients with urinary and fecal incontinence and in adults with constipation not responding to intensive conservative treatment. No data, however, are available on sacral neuromodulation therapy as a treatment option in adolescents with refractory functional constipation. Objectives: This study aimed to describe the short-term results of sacral neuromodulation in adolescents with chronic functional constipation refractory to intensive conservative treatment. Design: This is a retrospective review. Setting: This study took place at the Department of Surgery, Maastricht University Medical Centre, The Netherlands. Patients: Thirteen patients (all girls, age 10 - 18 years) with functional constipation according to the ROME III criteria not responding to intensive oral and rectal laxative treatment were assigned for sacral neuromodulation. Main outcome measures: When improvement of symptoms was observed during the testing phase, a permanent stimulator was implanted. Patients were prospectively followed up to at least six months after implantation of the permanent stimulator by interviews, bowel diaries, and Cleveland Clinic constipation score. Improvement was defined as spontaneous defecation ≥ 2 times a week. Results: At presentation, none of the patients had spontaneous defecation or felt urge to defecate. All patients had severe abdominal pain. Regular school absenteeism was present in 10 patients. After the testing phase, all but 2 patients had spontaneous defecation ≥ 2 times a week with a reduction in abdominal pain. After implantation, 11 (of 12) had a normal spontaneous defecation pattern of ≥ 2 times a week without medication, felt urge to defecate, and perceived less abdominal pain without relapse of symptoms until 6 months after implantation. The average Cleveland Clinic constipation score decreased from 20.9 to 8.4. One lead revision and 2 pacemaker relocations were necessary. Limitations: This study is limited by its small sample size, single-institution bias and retrospective nature. Conclusion: Sacral neuromodulation appears to be a promising new treatment option in adolescents with refractory functional constipation not responding to intensive conservative therapy. Larger randomized studies with long-term follow-up are required.
168 Sacral neuromodulation in childhood constipation
Introduction In children, the reported prevalence of constipation varies between 0.7% and 29.6%.1 Functional constipation occurs in all pediatric age groups, from newborns to young adults, and its severity may vary from mild and short-lived to severe and chronic with fecal impaction. Children are considered to have functional constipation once organic causes such as anatomical or neurological abnormalities and endocrine or metabolic disorders are ruled out, and when they meet the ROME III criteria.2 These children are traditionally treated by a combination of laxative treatment and behavioral approaches, such as toilet training and education. Long-term follow-up studies have shown, however, that, despite intensive medical treatment, functional constipation persists into adulthood in 25 to 30% of children.3 In those children with functional constipation not responding to maximal conservative treatment, more invasive surgical treatment options are often considered, such as colonic irrigation via a Malone antegrade continence enema or via a percutaneous endoscopic cecostomy. Unfortunately, these procedures are attended with substantial complication rates and, therefore, with relatively poor long-term success in children and adolescents.4 An alternative approach to bowel surgery in this group of young patients may be modulation of the extrinsic neural control of the large bowel or modulation of reflexes inhibiting large-bowel function. Electrical stimulation of sacral nerve roots has been shown to have a positive effect on peristalsis in the large bowel in patients with spinal cord injury.5 This stimulation can be achieved by the use of sacral neuromodulation (SNM) therapy. This minimally invasive surgical treatment has been successfully applied in adult patients with urinary and fecal incontinence and urinary retention.6, 7 Recently, SNM therapy showed promising results in adults with functional constipation not responding to intensive conservative treatment.8, 9 A large prospective multicentre study concluded that SNM therapy is an effective treatment of idiopathic slow- and normal-transit constipation in adults.10 No data, however, are available on SNM therapy in adolescents with refractory functional constipation. Therefore, the aim of this manuscript is to describe results of SNM therapy in adolescents Chapter with chronic functional constipation refractory to intensive conservative treatment.
Methods 8 After Institutional Review Board approval, a retrospective study was performed investigating adolescents who underwent SNM therapy for constipation at the Maastricht University Medical Centre, The Netherlands. All patients were referred by the Emma
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Children’s Hospital/Academic Medical Centre in Amsterdam, The Netherlands, a tertiary referral center for children with severe organic and functional defecation disorders. Constipation was defined according to the internationally accepted ROME III criteria for pediatric functional gastrointestinal disorders; the presence of at least 2 of the following criteria for at least 2 months prior to diagnosis; 1) 2 or fewer defecations per week, 2) at least 1 episode of fecal incontinence per week, 3) retentive posturing or stool retention, 4) painful or hard bowel movements, 5) presence of a large fecal mass in the rectum, 6) large diameter stools that may obstruct the toilet.2 To be eligible for percutaneous nerve evaluation (PNE) to assess feasibility of SNM therapy, patients had to fulfill Rome III criteria for functional constipation, not responding to intensive conservative treatment (oral laxatives, enemas or colonic lavage, and behavioral approaches). Patients were not eligible if they had organic pathology causing constipation, such as chronic IBD (Crohn’s disease or ulcerative colitis), or when they had a history of large-bowel surgery, congenital anorectal malformations, or neurological disease (complete spinal cord transection, multiple sclerosis, or spina bifida). Patients with significant psychological comorbidity (as judged by the investigator) or patients who were pregnant were also excluded. In patients eligible for SNM therapy, history taking, physical examination, whole-gut transit time study, defecography, MRI of the lower pelvic area, anorectal manometry, and rectal sensitivity measurement were performed. Baseline evaluation included completion of a bowel habit diary during 21 consecutive days in which details on defecation frequency were recorded while the patient received optimal conservative therapy. The presence of abdominal pain, straining, and sensation of incomplete evacuation were rated by the patient as occurring “never”, “seldom”, “sometimes”, “often” or “always” in the preceding week. Constipation severity was rated using the Cleveland Clinic constipation score. This score ranges from 0 - 30 with 0 indicating no symptoms and 30 indicating severe constipation as described by Agachan et al.11 Absenteeism from school activities and total number of hospital admissions were also recorded. Colonic transit time was assessed by the ingestion of radio-opaque markers and plain abdominal radiographs without the use of laxatives.12 Defecography was performed by retrograde infusion of radio-opaque barium paste followed by the assessment of rectal configuration, perineal descent, and presence of structural or functional pathology before, during, and after evacuation.13 The lower pelvic area was imaged without sedation or anesthesia with either a Siemens Magnetom Avanto 1.5 T (Siemens AG, Erlangen, Germany) or a Philips Panorama 1.0 T (Philips Medical Systems, Best, The Netherlands) MRI system, depending on availability. Anorectal manometry (mean resting pressure and mean squeeze pressure) was performed by the use of a pull-through technique. Rectal sensitivity measurement included measurement of rectal volume and testing of the rectoanal inhibitory reflex.14
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Consent was obtained by providing both patient and parents with all available information on therapy efficacy in adults, procedure and possible risks/benefits by different doctors on several occasions. Before resorting to an ileostomy or Malone stoma, risks (infection, scars) were acceptable to both patients and parents.
PNE and SNM procedure The technique of the percutaneous nerve evaluation (PNE) procedure has been described in detail by Schmidt et al.15 SNM consists of 2 stages: a sub-chronic diagnostic stage (PNE) for which 2 options are available (temporary wire (Medtronic Interstim model 3057, Minneapolis, Minnesota, USA) or tined lead (Interstim model 3889)) and a subsequent definitive implant stage in which the implantable neurostimulator (INS; Interstim II model 3058) is implanted (without tined lead if previously in situ). The advantages of testing with a tined lead are less lead migration after placement and, therefore, a longer possible testing period. Another advantage is that the definitive implant stage only consists of connecting the INS with the tined lead and removing the extension cable. This procedure is performed under local anaesthesia.6 Local anesthesia is preferred because it allows for patient input during the procedure.16 Correct placement was confirmed by observing motor and/or sensory responses, i.e. pelvic floor contraction, great toe flexion, and/or paresthesia in the anal or vaginal region.15 A 3-week screening period then commenced with continuous stimulation during daytime at low-amplitude sensory threshold settings (pulse amplitude 0.4 - 2.7 V; pulse width, 210 ms; frequency, 16Hz). During this diagnostic stage, all patients completed a 3-week bowel habit diary to assess outcome. To be eligible for implantation of the INS, patients had to have experienced a subjective improvement of symptoms without the use of laxatives or enemas as recorded in their bowel habit diary. Next to this, an increase in bowel frequency as defined as spontaneous defecation ≥ 2 times a week and/or a decrease in the total number of episodes of straining, incomplete evacuation, and abdominal pain had to be present.10 The INS was subsequently implanted in a subcutaneous pocket in the buttock and attached to the quadripolar tined lead. Following this second stage, the therapeutic settings were programmed to sensory threshold, which is usually lower than the motor response Chapter threshold, and patients were taught to use their own hand-held programmer.17 Patients were followed up at 1, 3, 6, and 12 months after permanent implantation. The efficacy was assessed by the Cleveland Clinic constipation score11 and a bowel habit diary. Use of additional laxatives or enemas and absenteeism from school were documented. 8 Any undesirable symptom that occurred during the stimulation was documented as an adverse event, regardless of whether it was considered to be related to the treatment.
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Statistics Continuous variables are tested for normality of distribution by the Shapiro-Wilk test. Data are presented both as means, SD, median and score ranges if applicable. Categorical variables are given as frequencies and percentages. In analyzing clinical measures in this cohort, each patient served as his or her own control, using baseline (optimal conservative treatment, care-as-usual) data compared with the outcome at each follow-up visit: at testing (screen), at 1 month after testing, at 3 months, at 6 months, and at 12 months after testing. At first, repeated measures ANOVA was performed up to 6 months of follow-up. Overall F-ratio tests are conservatively corrected for deviations from sphericity by Greenhouse-Geisser adaptations of the degrees-of- freedom. The weighted 6-month linear trend was calculated over all visits and tested for deviation from zero (no change). Next, a nonparametric analysis was performed using the Friedman test as an overall statistic and the Wilcoxon signed-rank test for testing differences between baseline and each follow-up visit. A p-value of less than 0.05 is considered to be statistically significant, but the low numbers of patients and the explorative nature of the cohort necessitate regarding the correlative results of this manuscript with both interest and care. All data analysis was done with SPSS for windows version 16.0 (SPSS Inc, Chicago, IL).
Results A total of 13 girls with a median age of 15.2 years (range, 10-18) underwent PNE; 12 of these patients received a permanent implant between February 2009 and March 2010. One year follow-up was available in only five patients, and 6 months follow-up in all 12 patients. The median age at onset of symptoms was 5 years (range, 1 - 12 years). Median therapy duration at time of inclusion was 7 years (range, 1 - 17 years). At baseline in all patients, all possible laxatives and several combinations of conservative treatment had been administered. Ten patients used daily oral polyethylene glycol electrolyte bowel lavage (Klean-Prep, Norgine BV) up to 2 L (60 - 120 g of PEG 3350 per day), 2 patients frequently used enemas, and 1 patient used daily retrograde colonic irrigation. In 1 patient, laxatives were administered daily through a Malone appendicostomy.
Baseline Investigations A colonic transit time study was performed in 9 patients (69%). Seven patients had slow transit constipation, and 2 had normal-transit constipation. Defecography was performed in 9 patients (69%). Five patients showed incomplete or no evacuation, and 3 patients had a radiological rectocele or outlet obstruction. Anorectal manometry was performed in 10 patients (77%) with normal anorectal parameters, including a normal rectoanal
172 Sacral neuromodulation in childhood constipation inhibitory reflex, in all 10 patients. MRI was performed in 11 patients (85%). No anatomical abnormalities were found. At baseline, none of the patients had spontaneous defecation without medication. Defecation was only achieved by daily oral lavage or daily colonic irrigation.
Outcome All patients but one treated in this cohort were evaluated with a tined lead during the testing stage. Twelve patients (92%) had a positive PNE test results and were consequently
Table 1 | Descriptive statistics Follow-up Baselinea Screen 1 month 3 months 6 months 12 months Defecation frequency Mean 1-5 5-0 4-9 5-6 4-9 4-8 SD 0-8 4-8 5-3 4-2 3-9 6-5 Minimum 0-3 1 0-7 2 1-3 1 Maximum 2-7 18 18-7 13-7 13 16-3 Cleveland Clinic constipationc (0-30) Mean 20-9 9-4 9-8 8-9 8-4 9-4 SD 3-4 4-7 5-4 4-4 3-3 3-2 Minimum 16 2 2 3 4 5 Maximum 26 19 21 16 14 13 Abdominal paind (1-5) Mean 4-8 2-7 2-9 3-2 3-2 3-0 SD 0-4 0-8 0-8 0-8 0-6 0-7 Minimum 4 1 1 2 2 2 Maximum 5 4 4 5 4 4 Strainingd (1-5) Mean 4-2 2-4 2-2 2-3 2-3 2-2 SD 0-7 1-5 1-3 1-3 1-3 1-1 Chapter Minimum 3 1 1 1 1 1 Maximum 5 5 5 5 5 3 Incomplete evacuationd (1-5) Mean 4-5 2-9 3-3 3-2 2-5 3-0 SD 0-7 1-7 1-7 1-6 1-5 1-6 8 Minimum 3 1 1 1 1 1 Maximum 5 5 5 5 5 5 All non-parametric tests between baseline and follow-up visits are statistically significant. aBaseline data with optimal conservative treatment. bDefecation frequency: episodes per week. cCleveland Clinic constipation: a score of 0 signifies no constipation and a score of 30 signifies severe constipation. dAbdominal pain, straining, and incomplete evacuation: a score of 1 indicates ‘never’ and a score of 5 indicates ‘always’.
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Defecation frequency p=0·008 20 k e e w
r 15 e y p c n e u
q 10 e r f
n o i t a
c 5 e f e D
0 Baseline Screen 1 3 6 12 Follow-up (months)
Figure 1 | Defecation frequency
Cleveland Clinic constipation score p<0·001 30
20
10
0 Baseline Screen 1 3 6 12 Follow-up (months) Figure 2 | Cleveland Clinic constipation score implanted with a pacemaker. PNE failed in 1 patient and the tined lead was explanted. Median follow-up was 7.3 months (range, 5.3 - 13.1). Descriptive statistics of all 12 patients undergoing implantation for defecation frequency, Cleveland Clinic constipation score, presence of abdominal pain, presence of straining, and sensation of incomplete evacuation measured at baseline and follow-up are presented in Table 1.
174 Sacral neuromodulation in childhood constipation
Repeated-measures ANOVA showed a statistically significant 6-months linear trend after implantation in the number of defecations (overall F-ratio = 5.33 by 2.4 and 26.5 df, p = 0.008 and linear trend effect F = 14.3 by 1 and 11 df, p = 0.003), Cleveland Clinic constipation score (overall F-ratio = 49.3 by 1.4 and 15.3 df, p<0·001 and linear trend effect F = 155.0 by 1 and 11 df, p<0.001), abdominal pain (overall F-ratio = 26.5 by 2.2 and 24.3 df, p<0.001 and linear trend effect F = 14·0 by 1 and 11 df, p = 0.003), straining (overall F-ratio = 9.4 by 2.7 and 29.7 df, p<0.001 and linear trend effect F = 11.5 by 1 and 11 df, p = 0.006) and sensation of incomplete evacuation (overall F-ratio = 6.1 by 2.3 and 25.6 df, p = 0.005 and linear trend effect F = 10.4 by 1 and 11 df, p = 0.008) without any use of laxatives or colonic irrigation (Figs. 1 – 5).
Abdominal Pain p<0·001 100 Never
s Seldom t 80 n e
i Sometimes t a
p Often 60 f o Always e g
a 40 t n e c r
e 20 P
0 Baseline Screen 1 3 6 12 Follow-up (months) Figure 3 | Distribution of abdominal pain
Straining p<0·001 100 Never s t Seldom n 80 Chapter e i t Sometimes a p
f 60 Often o
e Always g
a 40 t n e
c 8 r
e 20 P
0 Baseline Screen 1 3 6 12 Follow-up (months) Figure 4 | Distribution of straining
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Incomplete evacuation p=0·005 100 Never
s Seldom t
n 80 e i Sometimes t a p
Often
f 60 o Always e g
a 40 t n e c r
e 20 P
0 Baseline Screen 1 3 6 12 Follow-up (months) Figure 5 | Distribution of incomplete evacuation
The overall Friedman test p-value of weekly bowel movements over all visits was statistically significant (p<0.001). All Wilcoxon signed-rank tests between scores of baseline and follow-up were statistically significant (at screen p=0.003, at 1 month p=0.005, at 3 months p=0.002, and at 6 months p=0.004). The overall Friedman test p-values for the scores of the first half-year of the Cleveland Clinic constipation scale and the p-values for abdominal pain, straining and incomplete evacuation were p<0.001, p<0.001, p<0.001 and p=0.001. Again, for each of these 4 outcome parameters, all Wilcoxon signed-rank tests between scores of baseline and follow-up measurements were statistically significant (all p-values <0.05, results not shown). Use of additional laxatives or enemas was reported by 3 patients; 2 used laxatives or enemas only once, and 1 patient used enemas incidentally. Absenteeism from school was present in 10 patients (77%) at baseline and in none of the patients at 6-months follow- up. No admissions to the hospital were necessary during the first 6 months. Three adverse events were documented in 3 patients (23%) who received a permanent implant. All adverse events were classified as minor events. Two patients experienced pain at the site of the pacemaker that was resolved by replacing the device in the buttock. One patient experienced an undesired change of sensation that could not be managed by reprogramming and subsequently required a lead revision. Lead revision was performed by implanting a new lead into the contralateral third sacral foramen with similar results on constipation.
176 Sacral neuromodulation in childhood constipation
Discussion In our cohort, SNM appears to be a feasible option in treating constipation in adolescents not responding to optimal conservative treatment. Conservative therapy failed or was undesired in all patients. The creation of an ileostomy or a Malone stoma remained as the only alternative to SNM. After implantation, a significant increase in defecation frequency and a significant decrease in abdominal pain frequency were observed in all patients. Results expressed by defecation frequency, Cleveland Clinic constipation score, abdominal pain, straining, and incomplete evacuation were maintained up to 6 months follow-up in all patients with a permanent implantation. In 5 patients, the 12-month follow-up was available and results persisted. These results were achieved without the daily use of laxatives or enemas, although a relapse of symptoms occurred in 3 patients, of which 2 needed laxatives only once. No hospital admissions were necessary after implantation. Constipation in children and adolescents is usually treated by a combination of education, toilet training, and oral laxatives. Only in a minority of these patients, rectal clean outs or surgery are necessary. Long term results, however, of this approach are suboptimal. Staiano et al. have shown that chronic idiopathic constipation persists for more than 5 years in at least half of children treated conservatively.18 Moreover, others have shown that in at least 25% of children with functional constipation, symptoms persisted into adulthood.3 SNM therapy may therefore be a beneficial alternative treatment option. Kamm et al. showed a medium-term (1 – 55 months) success rate of 63% in adults with slow and normal constipation with a median age of 40 years.10 One patient in this study was 17 years-old. Viewed in this light, the high success rate of 92% in this cohort is remarkable. This may suggest that neuromodulation is more effective in younger patients. This article reports data on the possibility of SNM therapy in a difficult patient group. Patients served as their own control. A randomized controlled trial is needed to provide clear insight in the efficacy of SNM now that these results indicate major benefit to the patient. Quality-of-life data should be assessed in future studies. All PNE testing was performed under local anesthesia. In this age group, with the youngest patient being 10 years at the time of implant, general anesthesia may seem the obvious Chapter choice. However, we preferred local anesthesia to ensure perfect positioning of the lead based on sensory reaction to stimulation by the patient. We used the tined lead in all but 1 patient. This provides the advantage of less lead migration after placement and, therefore, a longer possible testing period with better results than 8 the temporary wire.19 Furthermore, permanent modulation is performed at the same lead position as during test stimulation. Another advantage is that the definitive implant stage only consists of connecting the INS and removing the extension cable. The downside of this approach is double the need for local anesthesia and increased risk of infection.
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Because SNM therapy is a minimally invasive procedure and offers the possibility to test results before permanent implant, it seems a preferable approach to alternative surgical procedures for constipation. The reported pain in 2 patients was resolved by replacement of the pacemaker. Pain is a concern in SNM and has been described before.20, 21 Pain may be caused by mechanical pressure on the implanted device, or it may be due to the stimulation itself. In this cohort we have only used the smallest pacemaker available. In children and young adults, the thickness of the subcutaneous layer is usually less than in adults and positioning of the pacemaker during implantation should be done with extra attention to avoid possible future pain reports. Stimulation was predominantly felt in the leg by 1 patient. Although the results on constipation were good, we decided to replace the lead to another foramen because reprogramming could not relieve complaints. No infections were seen in these patients. Providing insight in the success rate and occurrence of adverse events is difficult, because the exact working mechanism of SNM is still unknown. Rectal sensitivity has been described as unchanged, increased, or decreased.22-24 Changes in colonic transit time that have been described in both patients with fecal incontinence and constipation treated with SNM show seemingly contradicting results. SNM induces pancolonic propagating pressure waves and thus decreases colonic transit time in patients with constipation, whereas a reduced antegrade transport from the ascending colon and an increased retrograde transport from the descending colon at defecation have been described in fecal incontinence.25, 26 The effect of SNM on the colon may therefore be a result of neuromodulation at a more central level, and some studies have focused on corticoanal excitability in patients treated with SNM.27,28, 29 Ismail et al have tried transcutaneous electrical stimulation in children with constipation, also achieving promising results.30 Nine of 11 (81%) showed improvement of symptoms. A preceding trial showed increased colonic transit and peristaltic activity, which suggests a possible parallel working mechanism with SNM.
Conclusion SNM seems to be an effective short-term treatment in adolescents with chronic functional constipation refractory to intensive conservative treatment. These encouraging results with relatively minor adverse events stress the importance of further studies in larger patient groups with a longer follow up period. Furthermore, studies are necessary to unravel the underlying mechanisms of SNM.
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References
1. van den Berg MM, Benninga MA, Di Lorenzo C. Epidemiology of childhood constipation: a systematic review. Am J Gastroenterol 2006;101: 2401-2409. 2. Rasquin A, Di Lorenzo C, Forbes D, et al. Childhood functional gastrointestinal disorders: child/adolescent. Gastroenterology 2006;130: 1527-1537. 3. Bongers ME, van Wijk MP, Reitsma JB, Benninga MA. Long-term prognosis for childhood constipation: clinical outcomes in adulthood. Pediatrics;126: e156-162. 4. Curry JI, Osborne A, Malone PS. How to achieve a successful Malone antegrade continence enema. J Pediatr Surg 1998;33: 138-141. 5. Binnie NR, Smith AN, Creasey GH, Edmond P. Constipation associated with chronic spinal cord injury: the effect of pelvic parasympathetic stimulation by the Brindley stimulator. Paraplegia 1991;29: 463-469. 6. Melenhorst J, Koch SM, Uludag O, van Gemert WG, Baeten CG. Sacral neuromodulation in patients with fecal incontinence: results of the first 100 permanent implantations. Colorectal Dis 2007;9: 725-730. 7. Oerlemans DJ, van Kerrebroeck PE. Sacral nerve stimulation for neuromodulation of the lower urinary tract. Neurourol Urodyn 2008;27: 28-33. 8. Kenefick NJ, Nicholls RJ, Cohen RG, Kamm MA. Permanent sacral nerve stimulation for treatment of idiopathic constipation. Br J Surg 2002;89: 882-888. 9. Holzer B, Rosen HR, Novi G, et al. Sacral nerve stimulation in patients with severe constipation. Dis Colon Rectum 2008;51: 524-529; discussion 529-530. 10. Kamm MA, Dudding TC, Melenhorst J, et al. Sacral nerve stimulation for intractable constipation. Gut;59: 333-340. 11. Agachan F, Chen T, Pfeifer J, Reissman P, Wexner SD. A constipation scoring system to simplify evaluation and management of constipated patients. Dis Colon Rectum 1996;39: 681-685. 12. Bouchoucha M, Devroede G, Arhan P, et al. What is the meaning of colorectal transit time measurement? Dis Colon Rectum 1992;35: 773-782. 13. Goei R. Defecography: principles of technique and interpretation. Radiologe 1993;33: 356-360. 14. Meunier PD, Gallavardin D. Anorectal manometry: the state of the art. Dig Dis 1993;11: 252-264. 15. Schmidt RA, Senn E, Tanagho EA. Functional evaluation of sacral nerve root integrity. Urology 1990;35: 388-392. 16. Govaert B, Melenhorst J, van Gemert WG, Baeten CG. Can sensory and/or motor reactions during percutaneous nerve evaluation predict outcome of sacral nerve modulation? Dis Colon Rectum 2009;52: 1423-1426. 17. Koch SM, van Gemert WG, Baeten CG. Determination of therapeutic threshold in sacral nerve modulation for fecal incontinence. Br J Surg 2005;92: 83-87. Chapter 18. Staiano A, Andreotti MR, Greco L, Basile P, Auricchio S. Long-term follow-up of children with chronic idiopathic constipation. Dig Dis Sci 1994;39: 561-564. 19. Hetzer FH, Hahnloser D, Knoblauch Y, Löhlein F, Demartines N. New screening technique for sacral nerve stimulation under local aneasthesia. Tech Coloproctol. 2005;9: 25-28. 8 20. White WM, Mobley JD, 3rd, Doggweiler R, Dobmeyer-Dittrich C, Klein FA. Incidence and predictors of complications with sacral neuromodulation. Urology 2009;73: 731-735. 21. Matzel KE, Kamm M, Stosser M, et al. Sacral spine nerve stimulation for fecal incontinence: multicentre study. Lancet 2004;363: 1270-1276. 22. Uludag O, Morren G, Dejong CH, Baeten CG. Effect of sacral nerve stimulation on the rectum. Br J Surg 2005;92: 1017-1023.
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23. Michelsen HB, Buntzen S, Krogh K, Laurberg S. Rectal volume tolerability and anal pressures in patients with fecal incontinence treated with sacral nerve stimulation. Dis Colon Rectum 2006;49: 1039-1044. 24. Roman S, Tatagiba T, Damon H, Barth X, Mion F. Sacral nerve stimulation and rectal function: Results of a prospective study in fecal incontinence. Neurogastroenterol Motil 2008;20:1127-31. 25. Dinning PG, Fuentealba S, Kennedy ML, Lubowski DZ, Cook IJ. Sacral nerve stimulation induces pan-colonic propagating pressure waves and increases defecation frequency in patients with slow-transit constipation. Colorectal Dis 2006;9: 123-132. 26. Michelsen HB, Christensen P, Krogh K, et al. Sacral nerve stimulation for fecal incontinence alters colorectal transport. Br J Surg 2008;95: 779-784. 27. Sheldon R, Kiff ES, Clarke A, Harris ML, Hamdy S. Sacral nerve stimulation reduces corticoanal excitability in patients with fecal incontinence. Br J Surg 2005;92: 1423-1431. 28. Harris ML, Singh S, Rothwell J, Thompson DG, Hamdy S. Rapid rate magnetic stimulation of human sacral nerve roots alters excitability within the cortico-anal pathway. Neurogastroenterol Motil 2008;20:1132-9. 29. Blok BF, Groen J, Bosch JL, Veltman DJ, Lammertsma AA. Different brain effects during chronic and acute sacral neuromodulation in urge incontinent patients with implanted neurostimulators. BJU Int 2006;98: 1238-1243. 30. Ismail KA, Chase J, Gibb S, et al. Daily transabdominal electrical stimulation at home increased defecation in children with slow-transit constipation: a pilot study. J Pediatr Surgery 2009;44: 2388-2392.
180 Summary and Discussion
Summary and Discussion
Summary Gastrointestinal motility disorders may affect children of all ages. The most commonly found gastrointestinal motility disorders in the pediatric population are gastro-esophageal reflux disease, infantile hypertrophic pyloric stenosis and functional defecation disorders. Little is known about the exact pathophysiology of these gastrointestinal motility disorders in children. More knowledge of the pathophysiological mechanisms involved in these disorders may also contribute to the development of new therapeutic strategies. In this thesis, we aimed to further unravel the role of genetic, environmental and behavioral factors in the etiology of the most common pediatric gastrointestinal motility disorders. The most salient findings are summarized in this chapter.
Part I - Gastro-esophageal reflux disease Gastro-esophageal reflux disease (GERD) is a very common problem in children. Twin studies and familial aggregation studies have shown evidence for a genetic background of GERD. Several genetic loci have been found to be possibly associated with GERD, but, up till now, usually no genes have been confirmed to be associated with GERD in subsequent populations. This might be due to heterogeneity of studied populations with a similar heterogeneous etiology of GERD. Therefore, in Chapter 1, after detailed phenotyping, we performed genome-wide linkage analysis in a large multi-generational Dutch family with multiple family members affected with GERD. We assumed that the genetic background of GERD in this family would be homogeneous in affected family members. In this way, we identified several new genetic loci associated with the GERD phenotype in this family. Subsequent exome sequencing of the linkage regions however, has not yet lead to the identification of a variant likely to be associated with GERD in this family. Results of further studies in this family are awaited.
Part II - Infantile hypertrophic pyloric stenosis In Chapter 2, we provided an extensive overview of the current knowledge of genetic factors involved in the pathophysiology of infantile hypertrophic pyloric stenosis (IHPS). Although nowadays this motility disorder can be treated with a relatively simple surgical procedure, its pathophysiology is still poorly understood. The results of twin studies and familial aggregation studies clearly point to a genetic involvement, with high estimated heritability rates. Linkage studies in IHPS and one GWAS study identified several loci and specific genes, but nevertheless, no genes have been confirmed to be associated with IHPS in different populations, suggesting genetic heterogeneity. The role of nitric oxide synthase (NOS), a mediator of smooth muscle cell relaxation in the gut and frequently suggested to be associated with IHPS, still remains controversial. Next to this, we demonstrated that there are many clinical syndromes going along with IHPS, caused by
183 Summary and Discussion mutations in genes affecting many different pathways possibly important in the etiology of IHPS. This indicates that both isolated and non-isolated forms of IHPS have a similarly heterogeneous background.
Next to genetic factors, environmental factors may be associated with the development of IHPS. These environmental factors may have a direct influence on health, but may also have an indirect influence by means of changes in methylation of the genome and thereby differences in gene expression. There is a continuing enigma about the presence of seasonal variations in the incidence of IHPS. Many studies have been performed in very different populations with large differences in environmental factors such as climate, cultural habits, and nutrition patterns but also in genetic background. These factors can make it challenging to identify common specific etiological factors in case seasonal variation is found in different studies. Therefore, in Chapter 3, we performed a retrospective study in two different Dutch regions of the Netherlands to assess seasonality in the incidence of IHPS. Furthermore, we correlated the incidence of IHPS in both regions to several local climate factors. Seasonality in the incidence of IHPS was found only in one region, the province of North-Holland, correlating weakly with specific local climate factors. A peak in incidence was found in children born in winter months. In the other investigated region, such a seasonal pattern in the incidence of IHPS could not be demonstrated. No correlation with climate factors was found in this region. These results indicate that other environmental factors might be of influence in the seasonal variation in the incidence of IHPS found in one of the regions. These factors might have a direct influence on the health of the infant (probably in combination with a certain genetic constitution) or might act indirectly on the genome by changing methylation patterns.
Part III; Functional defecation disorders Little is known about the genetic background of childhood constipation. However, in clinical practice, parents of children often tell that functional constipation “runs in their family”. In chapter 4, we provided an extensive overview of studies investigating the genetic background of constipation. Familial aggregation studies and twin studies performed in families with constipation clearly point to a genetic involvement. Association studies and direct gene sequencing studies have failed in identifying genes that could be confirmed to be associated with constipation. Many genes have been found to be associated with Hirschsprung disease in children, but sequencing of these genes in individuals with constipation did not lead to the discovery of variants also associated with constipation. In this chapter, we also pointed out that constipation can be part of many clinical syndromes of which causative mutations are frequently known. We showed that these mutations are found in genes affecting all aspects of normal defecation physiology, providing evidence for a heterogenetic background of non-isolated forms of constipation.
184 Summary and Discussion
We could assume that isolated constipation is likely to be similarly heterogeneous, which might have complicated the identification of causative genes in previously performed genetic studies in constipation.
Next to a certain genetic constitution, behavioral factors are likely to be involved in the pathophysiology of functional defecation disorders. Behavioral problems have been found to be frequently present in constipated children. However, up till now, the addition of behavioral therapy to the regular treatment protocols has not proven to lead to better outcomes for children with constipation. There might be other factors influencing the behavior of a child with a functional defecation disorder that have not been identified to this date. As functional defecation disorders have proven to be more common among children with autism spectrum disorders, in Chapter 5, we were the first to investigate the prevalence of symptoms of autism spectrum disorders prospectively and systematically in a population of children presenting with functional defecation disorders. To our surprise and concern, we found that in nearly 30% of children visiting our specialized outpatient clinic, symptoms of an autism spectrum disorder were present. In 5% of the total study population, the diagnosis of an autism spectrum disorder had already been made. Given a prevalence of autism spectrum disorders in the general population of 0.6 to 1.0%, these results require further investigation. We stressed that clinicians should be alert for symptoms of autism spectrum disorders when evaluating a child with a functional defecation disorder.
Becoming toilet trained is an important milestone in a child’s early life and a step towards independency. In general, the majority of children become toilet trained for stools and urine before the age of 4 years. It is known that the presence of a functional defecation disorder may delay the moment of completion of toilet training. However, the possible influence of the presence of symptoms of autism spectrum disorders on the moment of achievement of toilet training in these children is unknown. Therefore, in Chapter 6, we compared the moment of completion of toilet training for stools and urine between three groups of children; children with a functional defecation disorder, children with a functional defecation disorder and concomitant symptoms of an autism spectrum disorder and controls from the general population. We found that children with a functional defecation disorder and concomitant symptoms of an autism spectrum disorder were later toilet trained for stools and urine compared to children with a functional defecation disorder only and healthy controls. We suggested that clinicians should be alert for symptoms of autism spectrum disorders in children presenting with a functional defecation disorder and toilet training problems.
The presence of a functional defecation disorder might not only affect a child but also his/her family. On the other hand, the family environment of the child might also have
185 Summary and Discussion an influence on the pathophysiology of functional defecation disorders in children. In Chapter 7, we described a study in which we investigated the psychological and physical health status, personality and child rearing practices of parents of children with and without functional defecation disorders. Higher levels of neuroticism, psychological distress and more physical complaints were found in parents of constipated children compared to the parents of controls. Remarkably, most differences could be attributed to differences between the mothers of the two study groups. These parental characteristics might hypothetically hamper the success of the standard treatment regimen for childhood constipation, consisting of providing structure in toileting by regular toilet sits, neglecting fecal incontinence and praising positive defecation behavior. We stressed that in children with functional constipation not responding to intensive conservative treatment parental factors possibly affecting the treatment should be evaluated and a more family-based multidisciplinary treatment strategy should be considered.
Symptoms of constipation may vary widely in intensity and severity among children. We have demonstrated that the pathophysiology of childhood constipation is very heterogeneous. Next to genetic factors, behavorial factors may also have an influence. When defining the efficacy of a new treatment strategy for a group of patients with constipation, it is extremely useful to phenotype the patients in such a way that the study group is as homogeneous as possible. In Chapter 8, we described that the application of a new experimental therapy, sacral neuromodulation therapy, led to spontaneous defecation without the need of laxatives and a significant decrease in abdominal pain and school absenteeism in a homogeneous group of female constipated adolescents. These patients all suffered from severe functional constipation and had not responded before to maximal intensive conservative treatment. Sacral neuromodulation therapy appeared to be an effective and relatively safe treatment option for female adolescents with severe functional constipation.
186 Summary and Discussion
Discussion and future perspectives The results of this thesis have further stressed the role of genetic, environmental and behavioral factors in the complex pathophysiology of pediatric gastrointestinal motility disorders. Little is known about the genetic background of pediatric gastrointestinal motility disorders as replication studies following association and linkage studies usually failed to confirm previous findings. Still, gastrointestinal motility disorders tend to run in families and an important role of genes in their pathophysiology is supported by familial aggregation studies. Next to this, this thesis demonstrated that non-isolated, syndromic forms of motility disorders in children are commonly found. We showed that there are many Mendelian disorders with very different genetic and biological backgrounds going along with gastrointestinal motility disorders in childhood, indicating genetic heterogeneity. This suggests that isolated gastrointestinal motility disorders in children are likely to have a strong heterogenic background as well, which may well explain the lack of repeatability of linkage and association study results in subsequent patient cohorts. Genes and proteins, almost without exception, are part of large biological pathways. Therefore, as shown in Chapters 2 and 4, studying non-isolated forms of motility disorders is valuable as it may identify pathophysiological pathways possibly associated with a gastrointestinal motility disorder. Other genes acting in the same pathway may be identified in disorders resembling the disorders under study. In this way, not single genes, but rather groups of genes coding for proteins functioning in (related) biological pathways might eventually come to light and learn us more about the genetic background of isolated motility disorders. We made a first attempt to group non-isolated phenotypes of both childhood constipation and infantile hypertrophic pyloric stenosis according to their presumed pathogenesis in Chapters 2 and 4. Hopefully, in the future, the results of our review studies may help other researchers in the field with the interpretation of results from association studies, linkage studies and total exome sequencing analyses. The presence of significant heterogeneity further underlines the need for detailed phenotyping in genetic and therapeutic research in pediatric gastrointestinal motility disorders. Genome wide association studies in large groups of unrelated individuals with homogeneous clinical characteristics are therefore less likely to succeed in the identification of genes associated with pediatric motility disorders. Linkage analysis in trios (father, mother, and sibling) and well-defined multigenerational families, on the other hand, have a high chance to reveal specific genes associated with motility disorders in the population under study. Although it is unlikely that genes identified in this way account for the same phenotype in large groups of unrelated individuals, studying these identified genes and their role in biological pathways may learn us more about the complex pathophysiological mechanisms related to gastrointestinal motility disorders.
187 Summary and Discussion
In the near future, much can also be expected from whole exome sequencing in determining the extent to which rare alleles explain the heritability of complex heterogeneous diseases such as motility disorders. To increase the efficiency of total exome sequencing in future research, a family-based approach (trios) or an extreme phenotype approach can be recommended. In an extreme phenotype approach, patients who are at both ends of a phenotype distribution can be selected for exome sequencing. The frequencies of alleles associated with the disease are enriched at both sides of the spectrum, making it more likely to identify novel candidate alleles. In the next years, the next generation sequencing field will gradually move to whole genome sequencing, whenever bioinformatic systems are ready to handle the large amount of data generated by this technique. This will also allow for variants in non-coding regions of the genome to come to light. The increasing accessibility of large local genomic databases such as ‘GoNL’ will further facilitate researchers in the gastrointestinal motility field to explore the tremendous possibilities brought by next generation sequencing. Still, when interpreting the results of such studies, the role of environmental factors should be taken in to account. Environmental factors such as nutrition patterns, cultural habits and climate may have a vast influence on health. Furthermore, the influences of certain agents such as medication or teratogenic factors on health should not be underestimated, especially in combination with an individual’s genetic and ethnic background. Indirect influences of environmental factors through methylation changes and thereby changes in gene activation may pass from generation to generation and may have large impact on one’s health. In the near future, it will become easier to investigate the effect of certain methylation patterns in study populations with gastrointestinal motility disorders as data on the ‘methylome’ of a general Dutch population will soon become accessible. Next to this, it might become useful to start biobanks in specialized motility centers to be able to collect genetic material for research purposes of large numbers of patients visiting the outpatient clinic. Obviously, constructing and controlling such a biobank goes along with many important ethical and legal considerations and therefore such a project should be carried out with the greatest carefulness. However, the presence of a biobank could enable genotyping after careful phenotyping of specific subgroups of patients, which may provide us more insight in the pathophysiology of motility disorders. Eventually, in the future, this might result in a situation in which phenotyping and genotyping of an individual patient may predict the chances for success of specific treatment options.
Behaviors of both children and their parents, associated with functional defecation disorders in childhood, deserve further investigation. The strikingly high percentage of symptoms of autism spectrum disorders found in children with functional defecation disorders, as described in this thesis, provides further evidence for a possible association between the two disorders. Still, it remains a challenge to explain a possible association. Behaviors associated with autism spectrum disorders might lead to problems during the
188 Summary and Discussion toilet training period, which is known to be a critical phase in the development of functional defecation disorders. There might also be a neurodevelopmental link to motility disorders in children with autism spectrum disorders affecting gastrointestinal motility in either an indirect or more direct way. For instance, autism spectrum disorders and functional defecation disorders could be part of a contiguous gene syndrome yet to be discovered. On the other hand, the presence of a functional defecation disorder and the frustrations going along with it might induce certain behaviors. It is very important to keep in mind that children included in the studies described in this thesis were recruited from a tertiary referral center for functional defecation disorders, probably resulting in a bias in our study population towards more severe cases. Next to this, in our studies, no definite diagnosis of an autism spectrum disorders was made, but only symptoms of autism spectrum disorders were investigated. Future studies should include more extensive standardized observational tests to be able to assess the true prevalence of autism spectrum disorders in children with functional defecation disorders. In order to further unravel the possible etiological association between autism spectrum disorders and functional defecation disorders, it would be interesting to perform gastrointestinal motility testing in children with both disorders, such as barostat studies combined with MR imaging of the brain. Sensory and motor thresholds following rectal distension in children with autism spectrum disorders could be assessed in this way. However, of course, there are many practical and ethical objections to perform such studies in this vulnerable group of children. In clinical practice, we stress the need for clinicians to be alert for symptoms of autism spectrum disorders in children with refractory functional defecation disorders and problematic toilet training. In this thesis, the question of cause and effect remains similarly unanswered regarding specific characteristics of parents of constipated children. The differences we have found in parents (especially mothers) of constipated and non-constipated children could be a consequence of the presence of a chronic and often frustrating disorder in their child. One might also hypothesize that the presence of certain parental characteristics might trigger defecation problems in their children, especially in combination with a genetic predisposition or the presence of other environmental factors. Future research should focus on longitudinal prospective studies to make the point of cause and effect more clear. In these studies, the role of mother and father in the family should be taken in to account, next to the health of other siblings and child-parent interactions as these probably important factors were not part of the current investigations.
189
Nederlandse samenvatting
Nederlandse samenvatting
Nederlandse samenvatting Motiliteitsstoornissen van het maag-darmkanaal (het gastro-intestinale systeem) komen voor bij kinderen van alle leeftijden. De meest voorkomende gastro-intestinale motiliteitsstoornissen op de kinderleeftijd zijn gastro-oesophageale reflux ziekte, pylorushypertrofie en functionele defecatie stoornissen. Er is echter weinig bekend over de pathofysiologie van deze motiliteitsstoornissen op de kinderleeftijd. Meer kennis over de pathofysiologische mechanismen zou kunnen bijdragen aan het ontwikkelen van nieuwe behandelingen voor kinderen met gastro-intestinale motiliteitsstoornissen. Het doel van dit proefschrift was het verder ontrafelen van de rol van zowel genetische factoren, omgevingsfactoren en gedragsfactoren in de ontstaanswijze van de meest voorkomende motiliteitsstoornissen bij kinderen. De belangrijkste bevindingen worden in dit hoofdstuk samengevat.
Deel I – Gastro-oesophageale reflux ziekte Gastro-oesophageale reflux ziekte (GORZ) is een veelvoorkomend probleem bij kinderen. Tweelingonderzoeken en aggregatiestudies binnen families hebben aangetoond dat er bewijs is voor een genetische achtergrond van GORZ. Verschillende genetische loci zijn in relatie gebracht met GORZ, maar tot op heden zijn er over het algemeen geen specifieke genen gevonden die met zekerheid geassocieerd konden worden met GORZ in vervolg- populaties. Dit is vrijwel zeker het gevolg van genetische heterogeniteit. Daarom werd in hoofdstuk 1, na gedetailleerde fenotypering, genetisch koppelingsonderzoek uitgevoerd in een grote Nederlandse familie bestaande uit meerdere generaties. Meerdere leden van deze familie hadden klachten passend bij GORZ. We veronderstelden dat de genetische achtergrond van GORZ binnen deze familie homogeen zou zijn in aangedane familieleden. Op deze manier identificeerden we verschillende nieuwe genetische loci die geassocieerd zijn met het GORZ fenotype in deze familie. Echter, exome sequencing van deze gekoppelde regio’s heeft tot dusver nog niet geleid tot de identificatie van een specifieke genetische variant die geassocieerd zou zijn met GORZ binnen deze familie. De resultaten van vervolgonderzoeken worden binnenkort verwacht.
Deel II - Pylorushypertrofie In hoofdstuk 2 boden we een uitgebreid overzicht van de huidige kennis over genetische factoren die betrokken zijn bij de pathofysiologie van pylorushypertrofie (PH). Ondanks het feit dat deze aandoening tegenwoordig met een relatief eenvoudige chirurgische ingreep gecorrigeerd kan worden, is de pathofysiologie nog steeds grotendeels onbegrepen. Tweelingstudies en familiaire aggregatiestudies wijzen duidelijk in de richting van een genetische component, met hoge geschatte erfelijkheidspercentages. Linkage studies en één genome wide association studie in patiënten met PH identificeerden verschillende
193 Nederlandse samenvatting genetische loci en specifieke genen. Tot dusver konden varianten in deze genen echter niet bevestigd worden in volgende populaties, wat suggestief is voor genetische heterogeniteit. Stikstofmonoxide (een mediator van relaxatie van gladde spiercellen in het maag-darmkanaal) is veelvuldig aangewezen als een potentieel belangrijke factor in de pathofysiologie van PH, maar de precieze rol hiervan blijft controversieel. Daarnaast toonden we aan dat er vele klinische syndromen zijn die samengaan met PH. Deze syndromen worden veroorzaakt door mutaties in verschillende genen die een rol spelen in vele verschillende pathways welke mogelijk van belang zijn in de pathofysiologie van PH. Dit impliceert dat zowel geïsoleerde als niet-geïsoleerde vormen van PH een heterogene achtergrond hebben. Naast genetische factoren kunnen ook omgevingsfactoren geassocieerd zijn met het ontstaan van PH. Deze omgevingsfactoren zouden een directe invloed kunnen hebben op de gezondheid, maar kunnen ook een indirecte invloed uitoefenen door bijvoorbeeld veranderingen in methylatie van het genoom en de daarop volgende veranderingen in genexpressie. Sinds lange tijd bestaat de vraag of de incidentie van PH onderhevig is aan seizoensinvloeden. Er zijn veel studies verricht in zeer verschillende populaties met grote verschillen in omgevingsfactoren zoals klimaat, culturele gewoonten en voedingspatronen, maar ook met grote verschillen in genetische achtergrond. Deze factoren maken het een uitdaging om gemeenschappelijke en specifieke etiologische factoren te identificeren wanneer er seizoensvariaties gevonden worden in verschillende studies. Om die reden beschreven wij in hoofdstuk 3 een retrospectieve studie die werd verricht in twee verschillende Nederlandse regio’s waarin we de seizoensvariatie in de incidentie van PH onderzochten. Daarnaast correleerden we de incidentie van PH in beide regio’s met verschillende lokale klimaatfactoren. Slecht in één van beide regio’s, de provincie Noord-Holland, werd seizoensvariatie in de incidentie van PH aangetoond, welke zwak correleerde met lokale klimaatfactoren. Een piek in de incidentie werd gevonden in kinderen geboren in de wintermaanden in deze regio. In de andere regio, Noord-Nederland, kon dit seizoenspatroon in de incidentie van PH niet significant worden aangetoond. In deze regio werd geen correlatie met lokale klimaatfactoren gevonden. Deze resultaten suggereren dat andere omgevingsfactoren van invloed kunnen zijn op de seizoensvariatie in de incidentie van PH zoals aangetoond in één van de regio’s. Deze factoren zouden een directe invloed kunnen hebben op de gezondheid van de pasgeborene (waarschijnlijk in combinatie met een zekere genetische constitutie), maar zouden ook een indirecte invloed kunnen hebben op het genoom door veranderingen in het methylatiepatroon.
Deel III; Functionele ontlastingsproblemen Er is weinig bekend over de genetische achtergrond van obstipatie op de kinderleeftijd. In de klinische praktijk vertellen ouders echter vaak dat obstipatie bij hen ‘een echte familiekwaal’ is. In hoofdstuk 4 boden we een uitgebreid overzicht van studies die de
194 Nederlandse samenvatting genetische achtergrond van obstipatie onderzochten. Aggregatiestudies binnen families en tweelingstudies wijzen duidelijk op een genetische component in de etiologie van obstipatie. Associatie studies en gen-sequencing studies zijn er niet in geslaagd om genen te identificeren die bewezen geassocieerd zijn met obstipatie. Verschillende genen zijn geassocieerd met de ziekte van Hirschsprung in kinderen, maar sequencing van deze genen in patiënten met obstipatie heeft niet tot de ontdekking geleid van varianten die alleen geassocieerd zijn met obstipatie. In dit hoofdstuk toonden we tevens aan dat obstipatie onderdeel kan zijn van zeer veel verschillende klinische syndromen waarvan de veroorzakende mutaties in veel gevallen bekend zijn. We toonden aan dat deze mutaties gevonden worden in genen die betrokken zijn bij alle aspecten van een normale defecatie fysiologie. Met deze bevinding werd aanvullend bewijs geleverd voor een heterogene achtergrond van zowel geïsoleerde als niet-geïsoleerde vormen van obstipatie. Dit zou de moeizame identificatie van genen betrokken bij obstipatie in eerder verrichtte studies kunnen verklaren.
Naast een zekere genetische constitutie, lijken gedragsmatige factoren ook betrokken te zijn bij de pathofysiologie van functionele defecatie stoornissen. Gedragsproblemen blijken in veel kinderen met obstipatie aanwezig te zijn. Echter, tot nu toe is nog niet bewezen dat het toevoegen van gedragstherapie aan de reguliere behandeling voor deze kinderen leidt tot betere uitkomsten. Er zouden andere, tot dusver nog onbekende, factoren kunnen zijn die de gedragingen van kinderen met functionele defecatie stoornissen beïnvloeden. In kinderen met autisme spectrum stoornissen is een hogere prevalentie van functionele defecatie stoornissen beschreven. In hoofdstuk 5 onderzochten wij als eersten op een prospectieve en systematische wijze de incidentie van symptomen van autisme spectrum stoornissen in kinderen die zich presenteerden met een functionele defecatie stoornis. Tot onze verbazing toonden we aan dat er bij bijna 30% van de kinderen die onze specialistische polikliniek bezochten, symptomen van autisme spectrum stoornissen aanwezig waren. In vijf procent van de totale studie populatie was de diagnose autisme spectrum stoornis reeds gesteld. In de algemene populatie wordt echter een prevalentie van 0.6 tot 1.0% beschreven, wat maakt dat onze resultaten nader onderzoek verdienen. We benadrukten in dit onderzoek dat artsen alert dienen te zijn op symptomen van autisme spectrum stoornissen wanneer zij een kind met een functionele defecatie stoornis in kaart brengen en behandelen.
Het bereiken van zindelijkheid is een belangrijke mijlpaal in het jonge leven van een kind en betekent een stap richting onafhankelijkheid. Over het algemeen wordt de meerderheid van de kinderen zindelijk voor ontlasting en urine voor de leeftijd van 4 jaar. Het was reeds bekend dat de aanwezigheid van een functionele defecatie stoornis het moment waarop zindelijkheid wordt bereikt kan verlaten. Echter, de invloed die de mede-aanwezigheid van symptomen van een autisme spectrum stoornis hier op zou kunnen hebben was nog
195 Nederlandse samenvatting onbekend. Om die reden werd in hoofdstuk 6 het moment van bereiken van zindelijkheid voor ontlasting en urine vergeleken tussen drie groepen kinderen; kinderen met een functionele defecatie stoornis, kinderen met een functionele defecatie stoornis met daarbij symptomen van een autisme spectrum stoornis en controles uit de algemene populatie. We concludeerden dat kinderen met een functionele defecatie stoornis met daarbij tevens symptomen van een autisme spectrum stoornis, gemiddeld op een later moment zindelijk werden voor ontlasting en urine dan kinderen met alleen een functionele defecatie stoornis en controles uit de algemene populatie. We gaven artsen de aanbeveling om alert te zijn op symptomen van autisme spectrum stoornissen bij kinderen die zich presenteren met een functionele defecatie stoornis en zindelijkheidsproblematiek.
De aanwezigheid van een functionele defecatie stoornis heeft niet alleen invloed op het kind zelf maar kan ook grote invloed uitoefenen op zijn/haar familie. Daarnaast zou de directe omgeving waarin het kind verkeert invloed kunnen hebben op het ontstaan van een functionele defecatie stoornis bij het kind. In hoofdstuk 7 beschrijven we een studie waarin we de lichamelijke en geestelijke gezondheid, de persoonlijkheid en het opvoedingsgedrag van ouders van kinderen met en zonder functionele defecatie stoornissen met elkaar vergeleken. Hogere niveaus van neuroticisme, psychologische stress en lichamelijke klachten werden gevonden in ouders van kinderen met functionele obstipatie dan in ouders van controle kinderen. Opmerkelijk was het feit dat de meeste verschillen die werden gevonden tussen de twee studiegroepen toegeschreven konden worden aan verschillen tussen de moeders. Deze ouderkarakteristieken zouden mogelijk invloed kunnen hebben op het succes van de standaard behandeling die wordt gegeven aan kinderen met functionele obstipatie. Deze behandeling bestaat, naast medicamenteuze behandeling, voor het grootste deel uit het bieden van structuur door middel van regelmatige toilettraining, het negeren van fecale incontinentie en het belonen van positief defecatie gedrag. Ouderkarakteristieken zouden extra onder de loep genomen moeten worden in het geval kinderen met functionele obstipatie niet reageren op intensieve conservatieve therapie. Een multidisciplinaire therapie, welke niet alleen gericht is op het kind zelf, maar tevens op de rest van het gezin, zou in deze situaties overwogen moeten worden.
De symptomen van obstipatie kennen een grote variatie in intensiteit en ernst onder kinderen. In dit proefschrift toonden we reeds aan dat de pathofysiologie van obstipatie zeer heterogeen is. Naast genetische factoren lijken gedragsmatige factoren ook een grote rol te spelen. Wanneer we de effectiviteit van een nieuwe behandelingsstrategie voor functionele obstipatie willen bepalen voor een groep patiënten, is het daarom van groot belang om de patiënten zodanig te fenotyperen dat de onderzoeksgroep klinisch zo homogeen mogelijk is. We beschreven in hoofdstuk 8 dat de toepassing van een nieuwe experimentele therapie,
196 Nederlandse samenvatting sacrale neuromodulatie, resulteerde in het optreden van spontane defecatie zonder het gebruik van laxantia en een significante vermindering in zowel buikpijn als schoolverzuim in een homogene groep vrouwelijke adolescenten met functionele obstipatie. Deze patiënten hadden allen last van ernstige functionele obstipatie en reageerden eerder niet op maximaal intensieve conservatieve behandeling. Sacrale neuromodulatie bleek een effectieve en relatief veilige behandeloptie voor vrouwelijke adolescenten met ernstige functionele obstipatie.
197
Contributing authors
Contributing authors
Contributing authors Mariel Alders Department of Clinical Genetics Academic Medical Center Amsterdam, the Netherlands
Marian K. Bakker Eurocat Northern Netherlands Department of Genetics University Medical Center Groningen Groningen, the Netherlands
Cor G. Baeten Department of Surgery Maastricht University Medical Center Maastricht, the Netherlands
Marc A. Benninga Department of Pediatric Gastroenterology and Nutrition Emma Children’s Hospital, Academic Medical Center Amsterdam, the Netherlands
Doeke Boersma Pediatric Surgical Center of Amsterdam Emma Children’s Hospital, Academic Medical Center Amsterdam, the Netherlands
Hein A.M. Daanen TNO, Soesterberg, the Netherlands MOVE research group, Faculty of Human Movement Sciences VU University Amsterdam Amsterdam, the Netherlands
Marieke van Dijk Department of Pediatric Psychology Emma Children’s Hospital, Academic Medical Center Amsterdam, the Netherlands
201 Contributing authors
Bas Govaert Department of Surgery Maastricht University Medical Center Maastricht, the Netherlands
Martha A. Grootenhuis Department of Pediatric Psychology Emma Children’s Hospital, Academic Medical Center Amsterdam, the Netherlands
Hugo A. Heij Pediatric Surgical Center of Amsterdam Emma Children’s Hospital, Academic Medical Center Amsterdam, the Netherlands
Raoul C. M. Hennekam Department of Pediatrics and Department of Translational Genetics Emma Children’s Hospital, Academic Medical Center Amsterdam, the Netherlands
Sofie Kuppens Clinical Child and Family Studies/ EMGO Institute for Health and Care Research VU University Amsterdam Amsterdam, the Netherlands
Rob W. Meijer Department of Surgery Medical Center Alkmaar Alkmaar, the Netherlands
Fred H. Nieman Department of Clinical Epidemiology and Medical Technology Assessment Maastricht University Medical Center Maastricht, the Netherlands
Ilse Noens Parenting and Special Education Research Unit and Leuven Autism Research KU Leuven Leuven, Belgium
202 Contributing authors
Gudrun Nürnberg Cologne Center for Genomics University of Cologne Cologne, Germany
Peter Nürnberg Cologne Center for Genomics University of Cologne Cologne, Germany
Matthijs W.N. Oomen Pediatric Surgical Center of Amsterdam Emma Children’s Hospital, Academic Medical Center Amsterdam, the Netherlands
Elise M. Philips Department of Pediatric Gastroenterology and Nutrition Emma Children’s Hospital, Academic Medical Center Amsterdam, the Netherlands
Wout O. Rohof Department of Gastroenterology Academic Medical Center Amsterdam, the Netherlands
Bart P. van Wunnik Department of Surgery Maastricht University Medical Center Maastricht, the Netherlands
203
List of publications
List of publications
List of publications This thesis Motility disorders and genetics: the future is bright B. Peeters, R.C. Hennekam J Pediatr Gastroenterol Nutr 2011 Dec;53 Suppl 2:S1-3
Genome-wide linkage analysis in a Dutch multigenerational family identifies new susceptibility loci for gastro-esophageal reflux disease (GERD) on chromosomes 4, 12 and 14 B. Peeters, M.A. Benninga, W.O. Rohof, M. Alders, G. Nürnberg, P. Nürnberg, R.C. Hennekam Submitted
Infantile hypertrophic pyloric stenosis: genetics and syndromes B. Peeters, M.A. Benninga, R.C. Hennekam Nat Rev Gastroenterol Hepatol 2012 Nov;9(11):646-60, published online July 2012
Seasonal variations in the incidence of infantile hypertrophic pyloric stenosis in two Dutch regions B. Peeters, M.W. Oomen, H.A.M. Daanen, M.K. Bakker, D. Boersma, R.W. Meijer, M.A. Benninga, H.A. Heij, R.C. Hennekam Submitted
Childhood constipation; an overview of genetic studies and associated syndromes B. Peeters, M.A. Benninga, R.C. Hennekam Best Pract Res Clin Gastroenterol 2011; Feb;25(1):73-88
Symptoms of autism spectrum disorders in children with functional defecation disorders B. Peeters, I. Noens, E.M. Philips, S. Kuppens, M.A. Benninga Submitted
Completion of toilet training in children with functional defecation disorders and concomitant symptoms of autism spectrum disorders B. Peeters, I. Noens, S. Kuppens, M.A. Benninga Submitted
Personality, psychological distress, physical health and child rearing practices of parents of children with functional constipation B. Peeters, M.A. Grootenhuis, M. van Dijk, M.A. Benninga Submitted
Sacral neuromodulation therapy: a promising treatment for adolescents with refractory functional constipation B.P. van Wunnik, B. Peeters, B. Govaert, F.H. Nieman, M.A. Benninga, C.G. Baeten Dis Colon Rectum 2012; Mar;55(3):278-85
207 List of publications
Other The prevalence of stressful life events including child sexual abuse in children with functional defecation disorders: a systematic review E.M. Philips, B. Peeters, A.H. Teeuw, A.G.E. Leenders, N. Boluyt, S.N. Brilleslijper-Kater, M.A. Benninga Submitted
Functional Nonretentive Fecal Incontinence: do enemas help? R.E. Burgers, J.B. Reitsma, C.J.C. Hoppenbrouwers, M.E.J Bongers, F. de Lorijn, W.P. Voskuijl, M.M. van den Berg, N. Bekkali, O. Liem, B. Peeters, C.M. Loots, M.P. van Wijk, M.A. Benninga Submitted
Parental knowledge of fecal incontinence in children M.A.van Tilburg, M. Squires, N. Blois-Martin, C. Williams, M.A. Benninga, B. Peeters, M. Ulshen J Pediatr Gastroenterol Nutr. 2012 Sep;55(3):283-7
Off-hours admission and mortality in two pediatric intensive care units without 24-h in-house senior staff attendance B. Peeters, N.J. Jansen, C.W. Bollen, A.J. van Vught, D. van der Heide, M.J. Albers Intensive Care Med. 2010 Nov;36(11):1923-7
Easily obtainable clinical features increase the diagnostic accuracy for latent autoimmune diabetes in adults: an evidence-based report M.W. Lutgens, M. Meijer, B. Peeters, M.L. Poulsen, M.J. Rutten, M.L. Bots, G.J. van der Heijden, S.S. Soedamah-Muthu
208 Dankwoord
Dankwoord
Dankwoord Dit boekje was er niet geweest zonder de inspanningen van alle kinderen en families die deelnamen aan de verschillende onderzoeken. Heel veel dank voor de geweldige inzet en de bereidheid mee te werken aan wetenschappelijk onderzoek.
Professor M.A. Benninga, lieve Marc, PB, wat een geweldig geluk dat ik in 2008 de mogelijkheid kreeg om in jouw groep promotieonderzoek te komen verrichten. De keuze om de start van mijn opleiding uit te stellen om eerst bij jou te promoveren bleek voor mij de juiste. Ik ben je enorm dankbaar voor je immense vertrouwen, je geduld, je onvoorwaardelijke steun en alles wat ik van je heb mogen leren op zowel persoonlijk als wetenschappelijk vlak. Naast een hoop hilariteit was er ook altijd ruimte voor serieuze gesprekken en leerde je me wat echt belangrijk is in het leven. Ik kijk met een fantastisch gevoel terug op de afgelopen vier jaar waarvoor heel veel dank!
Professor R.C. Hennekam, Raoul, het is een eer geweest om jou als promotor aan mijn zijde te hebben gehad. Je gestructureerde en grondige manier van werken in combinatie met jouw bijna encyclopedische kennis boden mij de juiste kaders om de wereld van de genetica te ontdekken. De ‘syndromen-bijbel’ die je me enkele jaren geleden overhandigde heeft echter niet geheel tot het mogelijk beoogde schrik-effect geleid… Ontzettend veel dank voor al je moeite, je geduld, je immer motiverende woorden en je oprechte interesse.
Hooggeleerde heren en vrouwe van de promotiecommissie, veel dank voor uw bereidheid om zitting te nemen in de promotiecommissie.
Grote dank gaat uit naar de gehele Vakgroep Kinderchirurgie van het Kinderchirurgisch Centrum Amsterdam voor hun hulp bij het includeren van patiënten met pylorushypertrofie voor genetisch onderzoek en voor het beschikbaar stellen van gegevens voor het seizoenenmanuscript. Hugo Heij, Matthijs Oomen en Doeke Boersma, dank voor alle hulp bij het incidentie-artikel.
Marian Bakker, dank voor de bijdrage aan het pylorushypertrofie artikel namens Eurocat. En Rob Meijer, dank voor het zo enthousiast beschikbaar stellen van de Alkmaarder data voor deze studie.
Ilse Noens, beste Ilse, onze Vlaams-Nederlandse samenwerking heeft twee mooie artikelen opgeleverd en daarnaast een aantal gezellige bezoekjes aan de stad Leuven. Veel dank voor je expertise en enthousiasme bij het opzetten, analyseren en schrijven van de studies over autisme spectrum stoornissen.
211 Dankwoord
Sofie Kuppens, beste Sofie, fijn dat jij de methodologische aspecten van de autisme manuscripten goed in de gaten hield. Bedankt voor al je hulp.
Professor C.G.M.I. Baeten en Bart van Wunnik, dank voor de prettige samenwerking in het sacrale neuromodulatie project bij kinderen.
Professor M.A. Grootenhuis, beste Martha, en Marieke van Dijk, fijn dat jullie mee wilden denken over de ouders-studie. Ik ben jullie zeer dankbaar voor jullie waardevolle en kundige hulp.
Hester Heidinga, dank voor al je hulp rondom mijn promotie.
Chris Bor, ik ben je zeer erkentelijk voor al je moeite en geduld bij het regelen van de lay-out van mijn proefschrift.
Veel dank is verschuldigd aan de vakgroep Kinder-MDL van het Emma Kinderziekenhuis voor alle hulp bij het opzetten van studies en bovenal voor de gezelligheid! Angelika Kindermann, Merit Tabbers, Bart Koot, Thalia Hummel en Herbert van Wering, veel dank voor alles, het was fijn om met jullie te mogen werken. Heleen, Reinie, Faiza en Giulia, dank voor jullie deskundige hulp bij de patiëntenzorg! Lieve Aaltje en Carin, jammer dat er voor mijn studies nooit samenwerking met jullie nodig was. In plaats daarvan hebben we hele fijne gesprekken gehad en veel gelachen, dank!
De geweldige onderzoeksomgeving heb ik mede te danken gehad aan alle arts-onder- zoekers die mij voorgingen bij de Poep- en Spuugpoli. Roos, Rijk, Wieger, Fleur, Maartje, Marloes en Arine, met jullie heb ik helaas niet meer gewerkt maar het is leuk om jullie nog geregeld te spreken bij bijeenkomsten. Maartje, destijds introduceerde jij mij als oudste co bij Marc en daar ben ik je nog steeds vreselijk dankbaar voor. Zie wat er van gekomen is! Marloes, de genetica studies die jij opzette zijn uiteindelijk in hele andere vormen uitgevoerd maar ik heb veel gehad aan jouw inspanningen.
Lieve Michiel, Noor, Olivia, Rosa en Claire, wat heb ik een leuke eerste onderzoeksjaren met jullie gehad. Toen ik aankwam in Amsterdam werd ik met open armen ontvangen door jullie. Jullie introduceerden me in de wondere wereld van de Kindermotiliteit. Congressen, feestjes en vakanties met jullie waren een daverend succes. Eén voor één verlieten jullie het honk op C2-312 en iedere keer opnieuw kon ik me niet voorstellen dat het bij mij ooit zo ver zou komen. Nu het dan toch zo ver is wil ik jullie heel erg danken voor de geweldige tijd die we samen hebben gehad. Het was een voorrecht om met jullie te mogen werken en ik ben blij dat we meer vrienden waren dan collega’s!
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En dan de huidige onderzoekers van de Poep- en Spuugpoli. Wat jammer dat ik jullie moet verlaten. Lieve Rachel, alias dokter Eierkoek, zonder anderen tekort te willen doen was jij mijn grote steun en toeverlaat de afgelopen jaren in de ‘Bunker’. Dank voor al je gezelligheid en voor het immense vertrouwen dat je altijd in mij had. Je bent een fantastisch vriendinnetje van me geworden en ik voel me vereerd om je als paranimf aan mijn zijde te hebben. Lieve Suzanne, dokter Smugy, hoe fijn dat ik via via een paar jaar geleden bij jou terecht kwam toen we een ‘leuk iemand’ zochten voor een promotietraject. De zoektocht is met jouw komst meer dan geslaagd! Ik benijd jouw grenzenloze energieniveau en enthousiasme. Je was een geweldige buurvrouw op links! Ik ga je erg missen. Succes met jouw laatste loodjes! Lieve Juliette, dokter Ruttenflutten, ondanks al je hypnosepraktijken sta je heerlijk nuchter in het leven en was je altijd in voor gezelligheid en goede gesprekken met een koffietje. Dank voor je immer luisterend oor, je liefheid en vriendschap. Ik mis je gezelligheid nu al! Lieve Marije, Marietje, onze sport- en carrièrevrouw in één. Ik bewonder jouw doorzettingsvermogen in het leven. Heel dapper dat je de keuze hebt gemaakt om de sport op een lager pitje te zetten voor fulltime onderzoek. Zet m op! Onze enige man, Daniel, alias Cornerman, wat een lef om als enige man plaats te nemen in het kippenhok op C2! Ik heb genoten van je nuchtere kijk op het leven en je adviezen in precaire vrouwelijke kwesties. Houd vol daar! Sophie, in het verre Columbus ben jij je promotietraject een tijdje geleden begonnen. Wat dapper van je om daar zo in je eentje naar toe te gaan. Heel veel plezier straks ook in Amsterdam binnen onze groep.
Professor Smout en Dr. A.J. Bredenoord, beste André, beste Arjan, dank voor jullie interesse in mijn onderzoek en de leerzame besprekingen.
Lieve Ramona, Jac en Sem, jullie waren fijne collega’s. Dank voor de leuke dagelijkse lunches!
Tamira, Breg, Sjoerd, Laurens, Wout, Boudewijn, Pim, Bram en Froukje, arts-onderzoekers van de volwassen-motiliteit, mede dankzij jullie was mijn onderzoekstijd een tijd van gezelligheid. Wout, dank voor je hulp bij de GERD studie en succes straks bij jouw promotie! (Oud-)onderzoekers van de volwassen MDL en het Tytgat Instituut, de congressen met jullie blijven mooie herinneringen. Nikè, lieve koffie- en congresmaat, ik mis onze gezellige bijeenkomsten op het Voetenplein.
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Elise, het was leerzaam en leuk om jou als wetenschappelijke stage student te begeleiden. Dank voor al je inzet en hulp.
Dr. J. Frenkel, beste Joost, ik ben je veel dank verschuldigd voor je adviezen omtrent de start van mijn opleiding in Utrecht en mijn promotietraject in Amsterdam. Je oprechte interesse in mijn onderzoek en je steun waardeer ik enorm.
Alle kinderartsen, collega arts-assistenten, verpleegkundigen en ondersteunend personeel van de vakgroep kindergeneeskunde van het Meander Medisch Centrum in Amersfoort, veel dank voor jullie hartelijke en warme ontvangst op mijn nieuwe werkplek!
Sanne, Gijs en Joris, onvergetelijke momenten tijdens onze studie bleken een uitstekende basis voor onze geneeskundige carrières. Jullie vriendschap is mij dierbaar.
Mijn oudhuysgenoten van Nachtegaalstraat 54bis, ook nu tijdens het werkende leven voelt het nog altijd zo vertrouwd met jullie. Dank voor jullie interesse in mijn werk op de Poeppoli. Lieve Perrine, wat fijn waren die cola-light pauzes met jou in het AMC! Succes met jouw promotie. Veel dank gaat uit naar mijn lieve jaarclubgenoten. Anna, Annette, Charlotte, Deodata, Fleur, Francine, Judith, Lotje, Nienke, Sylvia en Valentine, dank voor alle mooie momenten samen, onze vriendschap en jullie oprechte interesse in mijn onderzoek.
Lieve Dee, al op de eerste introductiedag in Utrecht in 2001 vonden we elkaar en sindsdien lopen onze levens synchroon. Onze vriendschap is mij heel veel waard. Wat een feest dat je weer in Utrecht bent komen wonen samen met Piet. Binnenkort staan we op jouw promotie! Ik ben heel trots op je.
Lieve Alexandra en Babette, mijn geweldige Bredase en nu Rotterdamse vriendinnetjes. Dank voor jullie onvoorwaardelijke vriendschap ondanks de ‘afstand’ die we altijd met veel plezier overbruggen. Met jullie is het altijd feest! Jullie zijn me ontzettend lief.
Mijn lieve schoonfamilie wil ik danken voor alle gezelligheid, warmte en hartelijkheid waarmee zij mij de afgelopen jaren altijd hebben omringd. Ik prijs me gelukkig met jullie.
Veel dank gaat uit naar mijn geweldige zusje Laura, tevens paranimf. Naast zusjes ook nog eens de allerbeste vriendinnen en elkaars steun en toeverlaat. Heel fijn dat je naast me wilt staan in je nieuwe functie als arts bij de verdediging van mijn proefschrift. Ik ben trots op je, Loet. Alex, veel dank voor je oprechte interesse en gezelligheid, ik ben blij dat je bij Laura hoort.
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Lieve papa en mama, mijn heerlijke, zorgenloze en liefdevolle jeugd bij jullie heeft de perfecte basis gevormd voor de rest van mijn leven. Ook nu nog motiveren en stimuleren jullie mij langs de zijlijn in alles wat ik doe, waardoor ik in staat ben het beste uit mijzelf te halen. Het is voor mij dan ook niet meer dan een vanzelfsprekendheid om dit proefschrift aan jullie op te dragen. Heel veel dank voor alles, jullie zijn geweldig!
En dan, mijn allerliefste, Koen. Niemand spreekt pylorushypertrofie zo knullig uit als jij. Maar laten we eerlijk zijn, zonder al jouw peptalks, jouw onvolprezen cateringkwaliteiten, jouw computernerd-support en bovenal al jouw liefde was dit nooit zo mooi geworden. Dank dat je er altijd voor me bent. Ik voel me enorm bevoorrecht met jou en kijk vol vertrouwen uit naar alles dat komen gaat.
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Curriculum Vitae
Curriculum Vitae
Curriculum Vitae Babette Peeters werd op 26 september 1983 geboren te Breda en groeide op in het Brabantse dorp Prinsenbeek. In 2001 behaalde zij haar Gymnasium diploma aan het Mencia de Mendoza Lyceum te Breda, waarna zij startte met haar studie Geneeskunde aan de Universiteit van Utrecht. Tijdens haar studie verrichtte zij wetenschappelijk onderzoek bij de afdelingen Klinische Genetica en Kinder Intensive Care van het Wilhelmina Kinderziekenhuis te Utrecht. Na het behalen van haar artsexamen in november 2007, werkte zij als arts-assistent Kindergeneeskunde in het Wilhelmina Kinderziekenhuis. In het voorjaar van 2008 werd zij aangenomen voor de opleiding tot kinderarts in het Wilhelmina Kinderziekenhuis/UMC Utrecht onder leiding van Dr. J. Frenkel. Op dat moment kreeg zij tevens de mogelijkheid om in het najaar van 2008 te starten met een promotieonderzoek onder leiding van Prof. M.A. Benninga en Prof. R.C.M. Hennekam in het Emma Kinderziekenhuis/AMC te Amsterdam, waarvan dit proefschrift het resultaat is. Tijdens deze onderzoeksperiode verrichtte zij klinisch werk op de “Poeppoli” van het Emma Kinderziekenhuis. In oktober 2012 kon zij alsnog aanvangen met haar opleiding tot kinderarts vanuit het Wilhelmina Kinderziekenhuis/UMC Utrecht en begon zij haar perifere stage in het Meander Medisch Centrum te Amersfoort onder leiding van Dr. P.H.G. Hogeman en Dr. J. Frenkel.
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AMC Graduate School for Medical Sciences PhD Portfolio Summary of PhD training, teaching and parameters of esteem Name PhD student: B. Peeters PhD period: October 2008 - September 2012 Name PhD supervisors: Prof. M.A. Benninga and Prof. R.C.M. Hennekam 1. PhD training Year Workload (ECTS) General courses - Practical Biostatistics 1.1 - Clinical Datamanagement 0.3 - Clinical Epidemiology 0.6 - BROK (‘Basiscursus Regelgeving Klinisch Onderzoek’) 0.9 Specific courses - Genetic Epidemiology 1.1 Seminars, Workshops and Masterclasses - Dutch Pediatric Federation: Young Investigators Day, Veldhoven 2011 0.5 - Amsterdam Pediatric Symposium, Amsterdam 2009 - 2012 2 Presentations Oral presentations: - Sacral neuromodulation in children with constipation: Annual Spring 2010 - 2012 0.5 Conference Dutch Society for Gastroenterology, Veldhoven - Autism spectrum disorders in children with constipation: Dutch Pediatric 2011 0.5 Federation: Young Investigators Day, Veldhoven; European Society for Pediatric Gastroenterology and Nutrition: 0.5 Young Investigators Forum; - Toilet training in children with symptoms of autism spectrum disorders and 2012 0.5 functional defecation disorders: Annual Spring Conference Dutch Society for Gastroenterology, Veldhoven Poster presentations: - Sacral neuromodulation in children with constipation: Annual Spring 2010 - 2012 0.5 Conference Dutch Pediatric Federation, Veldhoven Amsterdam Pediatric Symposium, Amsterdam; 0.5 Digestive Disease Week, New Orleans, USA; 0.5 5th Pediatric Motility Conference, AMC Amsterdam; 0,5 Congress of the European Academy of Paediatric Societies, Copenhagen, 0.5 Denmark - Autism spectrum disorders in children with constipation: Amsterdam 2011 - 2012 0.5 Pediatric Symposium, Amsterdam; Digestive Disease Week, Chicago, USA 0.5 - Toilet training in children with symptoms of autism spectrum disorders and 2012 0.5 functional defecation disorders: Digestive Disease Week, San Diego, USA - Unravelling the genetic pathophysiology of IHPS: Digestive Disease Week, 2012 0.5 San Diego, USA
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- Prevalence of child (sexual) abuse in functional defecation disorders: 2011 - 2012 0.5 Digestive Disease Week, San Diego, USA (Inter)national conferences - Annual Pediatric Gastroenterology Symposium Amsterdam 2009 - 2012 1 - Annual Conference Dutch Pediatric Federation, Veldhoven 2008 - 2011 1 - Annual Spring Conference Dutch Society for Gastroenterology, Veldhoven 2009 - 2012 1 - Current Perspectives in Chronic Constipation: A Scientific and Clinical 2009 1 Symposium, London, UK - The 2nd International Symposium on the Development of the Enteric Nervous 2009 1 System: Cells, Signals and Genes, London, UK - Congress of the European Academy of Paediatric Societies, Copenhagen, 2010 1 Denmark - Digestive Disease Week, American Gastroenterology Association, New 2010 - 2012 3 Orleans/Chicago/San Diego, USA - 5th Pediatric Motility Conference, AMC Amsterdam 2011 1 Other - European Society for Pediatric Gastroenterology and Nutrition: Young 2012 1.5 Investigators Forum 2. Teaching Year Workload (ECTS) Lecturing Teaching sessions on childhood defecation disorders for Dutch Federation of 2009, 2010 1 Physiotherapists, Doorn Tutoring, Mentoring Mentoring students. Project: Prevalence of autism spectrum disorders in 2010 - 2011 4 children with functional defecation disorders Supervising Supervising Research internship student (6 months). Project: Prevalence of 2011 2 child (sexual) abuse in children with functional defecation disorders Other - - 3. Parameters of Esteem Year Workload (ECTS) Grants - - Awards and Prizes 2011, 2012 - - Poster of distinction Digestive Disease Week 2012, San Diego, USA - Poster of distinction Conference of European Society of Pediatric Gastroenterology and Nutrition 2011, Sorrento, Italy
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