DOCSLIB.ORG

Two Filipino Patients with 6-Pyruvoyltetrahydropterin Synthase Deficiency

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Two Filipino Patients with 6-Pyruvoyltetrahydropterin Synthase Deficiency CASE REPORT Two Filipino Patients with 6-Pyruvoyltetrahydropterin Synthase Deficiency John Karl L. de Dios1,2, Mary Anne D. Chiong,1,2 1Department of Pediatrics, College of Medicine and Philippine General Hospital, University of the Philippines Manila; 2Institute of Human Genetics, National Institutes of Health, University of the Philippines Manila ABSTRACT enzymes: guanosine triphosphate cyclohydrolase Hyperphenylalaninemia can result from defects in either the (GTPCH), 6-pyruvoyltetrahydropterin synthase (PTPS), phenylalanine hydroxylase (PAH) enzyme or in the synthesis or dihydropteridine reductase (DHPR) and pterin-4a- recycling of the active pterin, tetrahydrobiopterin (BH4), which is an carbinolamine dehydratase (PCD). The first two enzymes are obligate co-factor for the PAH enzyme, as well as tyrosine hydroxylase and tryptophan hydroxylase. One of the most common causes of BH4 involved in the biosynthesis of tetrahydrobiopterin, the last 3 deficiency is a defect in the synthesis of 6-pyruvoyltetrahydropterin two in its regeneration. A third enzyme in the biosynthesis synthase (PTPS) enzyme. Patients present with progressive neurological of BH4 is sepiapterin reductase, but its deficiency is not disease such as mental retardation, convulsions and disturbance of associated with hyperphenylalaninemia 1 (Figure 1). tone and posture despite strict adherence to diet and good metabolic Clinical manifestations for a severe PAH defect or BH4 control. The authors report the first two cases of PTPS deficiency in the synthesis/recycling defect can be similar, with patients Philippines. Both are females with initial phenylalanine levels of more presenting with progressive neurological impairment than 1300 umol/L who continued to develop neurologic deterioration during infancy. Since management of these patients will despite good metabolic control and strict adherence to diet. Further depend on the etiology, determining the correct cause for investigation showed that they both had PTPS deficiency. Treatment the hyperphenylalaninemia is important. was started with BH4, L-dopa/carbidopa, and 5-hydroxytryptophan Diagnostically, defects in BH4 synthesis/recycling would (5HT) with concomitant significant improvements in their neurologic and developmental outcomes. show either a decreased DHPR activity or an abnormal pterin high performance liquid chromatography (HPLC) analysis Key Word: hyperphenylalaninemia, 6-Pyruvoyltetrahydropterin synthase, such as accumulation of neopterin in biopterin-synthetase tetrahydrobiopterin deficiency; high levels of pterins in DHPR deficiency; and low biopterin and high neopterin levels in PTPS deficiency. Introduction PAH enzyme deficiency on the other hand, will have normal 4,5 Phenylalanine (PHE) is an essential aromatic amino acid, DHPR activity and high levels of pterins. mainly metabolized in the liver by the PHE hydroxylase Here we present two cases of patients detected to have (PAH) system. The PAH enzyme requires a cofactor, the elevated PHE, initially treated as cases of classical PKU, active pterin, tetrahydrobiopterin (BH4), which is also an which on further testing were found to have BH4 synthesis obligate co-factor for tyrosine hydroxylase and tryptophan defects. hydroxylase1 (Figure 1). Defects in either PAH or the synthesis or recycling of BH4 may result in hyperphenylalaninemia, as Clinical reports well as deficiency of tyrosine, L-dopa, dopamine, melanin, Patient 1 catecholamines, and 5-hydroxytryptophan.1 Patient 1 is a 1 year old girl, third child of non- th Severe PAH deficiency results in classical phenylketonuria consanguineous parents. She was first seen on the 19 (PKU) with blood PHE levels more than 1200 µmol/L when day of life, after her newborn screening showed elevated individuals are on a normal protein intake. Milder defects phenylalanine levels (1400 µmol/L). At that time, the are termed hyperphenylalaninemia.1 Tetrahydrobiopterin patient was noted to be slightly hypertonic with increased deficiency, a variant of hyperphenylalaninemia, sleeping time. She was started on a protein restricted diet may be caused by deficiency of one of the following and phenylalanine free formula with regular follow-up at our metabolic clinic. Despite good compliance with the recommended diet and phenylalanine levels less than 400 µmol/L, the patient developed seizures at 4 months of life and subsequently Corresponding author: Mary Anne D. Chiong, MD presented with developmental regression, loss of head Institute of Human Genetics, National Institutes of Health, control and hypotonia. These were initially attributed to the University of the Philippines Manila possible effects of the increased PHE levels in the neonatal 625 Pedro Gil Street, Ermita Manila 1000, Philippines Telephone: +632 536 7002 period. She was then referred to a neurologist and started E-mail: [email protected] on anti-convulsant therapy. 18 ACTA MEDICA PHILIPPINA VOL. 43 N0. 2 2009 6-Pyruvoyltetrahydropterin synthase deficiency Guanosine triphosphate (GTP) GTPCH s s Neopterin s Dihydroneopterin triphosphate GFRP s PTPS s s – 6-Pyruvoyl-tetrahydropterin + SR s Phenylalanine Tyrosine Tryptophan Arg s Tetrahydrobiopterin DHPR PAH TH TPH NOS s s s PCD s s q-Dihydrobiopterin s Pterin Tyrosine L-DOPA 5-OH-Tryptophan Cit 4a-carbinolamine + NO s s s s Dopamine Serotonin Biopterin Primapterin s s HVA 5HIAA Figure 1. Aromatic amino acid hydroxylases and function of tetrahydrobiopterin. GTPCH - GTP cyclohydrolase I, PTPS - 6- pyruvoyltetrahydropterin synthase, SR - sepiapterin reductase, DHPR - dihydropteridine reductase, PCD – pterin-4a-carbinolamine dehydratase, GFRP - GTPCH feedback regulatory protein, PAH - phenylalanine hydroxylase, TH - tyrosine hydroxylase, TRH - tryptophan hydroxylase, NOS - nitric oxide synthase, HVA - homovanillic acid, 5HIAA - 5-hydroxyindoleacetic acid2 At approximately 7 months, BH4 deficiency was phenobarbital maintenance was abruptly stopped by the considered due to the persistence of seizures and parent. Seizures have been noted to decrease in frequency developmental delay. Investigations included DHPR following re-administration of the phenobarbital. activity, which was normal (done at The Children’s Hospital Repeat prolactin level showed 710.3 µIU/mL, which was at Westmead, Sydney Australia), and pterin levels which still mildly elevated, thus levodopa was increased to 6mg/ revealed PTPS deficiency (done at Taipei Veterans General kg/day. Hospital, Taiwan). Prolactin levels also showed significantly At the time of this writing, she is maintained on elevated results at 1124.5 µIU/mL (n.v. 80-500 µIU/mL). levodopa/carbidopa at 6 mg/kg/day, 5HT at 5 mg/kg/ She was initially started only on levodopa/carbidopa day, and BH4 tablets at 3 mg/kg/day. Anti-convulsants because of the unavailability of the BH4 and 5HT tablets. The (oxcarbazepine and phenobarbital) have been slowly patient was started at a dose of 1 mg/kg/day and increased tapered with seizures occurring less frequently. The patient weekly by 1 mg/kg/day with no adverse reactions noted. has been off protein restriction for two months now with One month after starting levodopa treatment, the patient PHE levels remaining within the normal range. There is still was noted to have improvement in motor skills, with slight some developmental delay in expressive language with the head control, and better muscle tone. At this time, 5HT patient only able to utter single syllables. However, the rest tablets were also started at 1 mg/kg/day. However, the of the developmental skills are now within the acceptable patient developed loose bowel movements with increased standard for age. frequency. Increments were decreased to 0.3mg/kg/day weekly until 5 mg/kg/day was achieved. Three weeks Patient 2 later, patient was also started on BH4 tablets at a dose of 3 Patient 2 is a girl, now 2 years of age. She is the second mg/kg/day. No untoward reactions were noted after intake child of non-consanguineous parents. The older sibling has of BH4 tablets. Within 1 month after starting BH4 tablets, mental retardation. Newborn screening was not done at the seizure episodes disappeared, recurring only after birth. At 3 months of life, she had spasticity and seizures, VOL. 43 N0. 2 2009 ACTA MEDICA PHILIPPINA 19 6-Pyruvoyltetrahydropterin synthase deficiency thus newborn screening was recommended which showed cases where there is poor metabolic control. The increased elevated PHE levels (1300 µmol/L). She was diagnosed to level of PHE results in an imbalance of other large neutral have classical PKU, referred to our metabolic clinic and amino acids within the brain, resulting in decreased brain started on protein restricted diet. Although there was regular concentrations of tyrosine and serotonin6. Therefore, the follow-up, metabolic control was poor, which was attributed finding of persistent neurologic manifestations despite to limited and irregular availability of the phenylalanine- normal to near normal levels of PHE points more to a BH4 free milk. Seizures were uncontrolled even with anti- synthesis/recycling defect, as seen in patient 1. Similarly, convulsant therapy (topiramate and phenobarbital) and Patient 2 was suspected with this disorder after careful patient had poor developmental progress with persistent evaluation of the metabolic status (regular milk supply and head lag and hypotonia. improving PHE levels). Starting at 1 year 9 months of age, PHE-free formula Both patients described here were confirmed to have supply became more regular. Although
Load more

Recommended publications
  • Guide for Hyperphenylalaninemia
    TM Guide For Hyperphenylalaninemia Laurie Bernstein, MS, RD, FADA Cindy Freehauf, RN, CGC Laurie Bernstein, MS, RD, FADA Fellow of the American Dietetic Association Assistant Professor- Department of Pediatrics Director, IMD Nutrition The Children's Hospital, Aurora CO Cindy Freehauf, RN, CGC Assistant Professor- Department of Pediatrics Clinical Coordinator, IMD Clinic The Children's Hospital, Aurora CO A special thank you to: Kathleen M. Martin, BS, BA for her enthusiasm for learning and excellent graphic skills. Intern, IMD Clinic The Children's Hospital, Aurora CO Second Edition Review Committee: Casey Burns, RD Janet A. Thomas, MD Metabolic Nutritionist Associate Professor, Pediatrics The Children's Hospital, Aurora CO Director, IMD Clinic The Children's Hospital, Aurora CO Sommer Myers, RD Metabolic Nutritionist Erica L. Wright, MS, CGC The Children's Hospital, Aurora CO Certified Genetic Counselor The Children's Hospital, Aurora CO Shannon L. Scrivner, MS, CGC Certified Genetic Counselor The Children's Hospital, Aurora CO Acknowledgments: Educational grant provided by Nutricia North America The Genetic Counseling Graduate Students of The University of Colorado at Denver and Health Sciences Center. TCH logo is a Licensed Trademark, all rights reserved. The Inherited Metabolic Clinic at The Children’s Hospital in Aurora, CO serves the Rocky Mountain Plains Region and at least 130 individuals with hyperphenylalaninemia (PKU). Children and families require a great deal of complex information, most often new and alien to their experience, in order to establish and maintain consistent and effective treatment. Our experience with the process of sharing such information with families motivated us develop this anticipatory guidance book with teaching aids.
    [Show full text]
  • Malignant Hyperphenylalaninemia Tetrahydrobiopterin (BH4) Phenylalanine
    Pediat. Res. 13: 1 150-1 155 (1979) Dihydropterine reductase (DHPR) phenylketonuria malignant hyperphenylalaninemia tetrahydrobiopterin (BH4) phenylalanine Malignant Hyperphenylalaninemia-Clinical Features, Biochemical Findings, and Experience with Administration of Biopterins D. M. DANKS, P. SCHLESINGER, F. FIRGAIRA, R. G. H. COTTON. B. M. WATSON, H. REMBOLD. AND G. HENNINGS Genetics Research Unit, Royal Children S Hospital Research Foundation, and Department of Paediatrics, Universi1.y of Melbourne, Parkville, Australia (D. M. D., P. S., F. F.. R. G. H. C., B. M. W.) and Max Planck Institutfur Biochemie. Germany (H. R., G. H.) Summary has been attributed to defective production of neurotransmitters derived from hydroxylation of tyrosine and of tryptophan (3, 4). Four cases of malignant hyperphenylalaninemia (MHPA) are The results of treatment with L-dopa and 5-hydroxytryptophan described. Pretreatment serum phenylalanine levels were 1.5, 3.0, support this contention (2, 3. 7). 2.4, and 0.9 mmoles/l. Dihydropteridine reductase (DHPR) defi- Four patients with MHPA seen in Melbourne since 1963 are ciency was proven in one patient by assays on cultured fibroblastic presented. One patient has been shown to have DHPR deficiency cells and was presumed in her sibling and in another deceased and her sister is presumed to have died of this defect. Both parents patient whose parents' fibroblastic cells show approximately 50% of another baby had DHPR levels in the heterozygote range of normal enzyme activity. DHPR and phenylalanine hydroxylase suggesting DHPR deficiency as the cause of her death. The 4th deficiency were excluded by assays on liver obtained at autopsy in baby had neither PH or DHPR deficiency and defective BH4 the 4th patient.
    [Show full text]
  • Tetrahydrobiopterin Loading Test in Hyperphenylalaninemia
    003 1-399819113005-0435$03.00/0 PEDIATRIC RESEARCH Vol. 30, No. 5, 1991 Copyright 0 199 1 International Pediatric Research Foundation, Inc. Pr~ntc.d in U.S. A Tetrahydrobiopterin Loading Test in Hyperphenylalaninemia ALBERT0 PONZONE, ORNELLA GUARDAMAGNA, SILVIO FERRARIS, GIOVANNI B. FERRERO, IRMA DIANZANI, AND RICHARD G. H. COTTON InstiflifeofPediatric Clinic(A.P., O.G., S.F., G.B.F., I.D.], University of Torino, 10126 Torino, Italy and Olive Miller Laboratory [R.G.H.C.],Murdoch Institute, Royal Children's Hospital, Vicroria,Australia 3052 ABSTRACT. Some cases of primary hyperphenylalanine- PKU to describe some cases clinically unresponsive to a Phe- mia are not caused by the lack of phenylalanine hydroxyl- restricted diet and later shown to be due to BH4 deficiency ase, but by the lack of its cofactor tetrahydrobiopterin. ( 1-4). These patients are not clinically responsive to a phenylal- By analyzing all the essential components of the complex anine-restricted diet, but need specific substitution therapy. hydroxylation system of aromatic amino acids, it became appar- Thus, it became necessary to examine all newborns ent that a defect in the BH4 recycling enzyme DHPR (EC screened as positive with the Guthrie test for tetrahydro- 1.66.99.7) and two defects in BH4 synthetic pathway enzymes, biopterin deficiency. Methods based on urinary pterin or guanosine triphosphate cyclohydrolase I (EC 3.5.4.16) and 6- on specific enzyme activity measurements are limited in PPH4S, may lead to cofactor deficiency resulting in HPA and in their availability, and the simplest method, based on the impaired production of dopamine and serotonin (5-7).
    [Show full text]
  • Relevance to Neurological Damage
    Postgrad Med J: first published as 10.1136/pgmj.62.724.113 on 1 February 1986. Downloaded from Postgraduate Medical Journal (1986) 62, 113-123 Pteridines and mono-amines: relevance to neurological damage I. Smith, D.W. Howells and K. Hyland Institute ofChildHealth (University ofLondon), 30 Guilford Street, London WCIN2NR, UK. Summary: Patients with phenylalanine hydroxylase deficiency show increased concentrations of biopterins and neopterins, and reduced concentrations ofserotonin and catecholamines, when phenylalan- ine concentrations are raised. The pterin rise reflects increased synthesis of dihydroneopterin and tetrahydrobiopterin, and the amine fall a reduction in amine synthesis due to inhibition by phenylalanine of tyrosine and typtophan transport into neurones. The pterin and amine changes appear to be independent of each other and are present in the central nervous system as well as the periphery; they disappear when phenylalanine concentrations are reduced to normal. Patients with arginase deficiency show a similar amine disturbance but have normal pterin levels. The amine changes probably contribute neurological symptoms but pterin disturbance is not known to affect brain function. Patients with defective biopterin metabolism exhibit severely impaired amine synthesis due to tetrahydrobiopterin deficiency. Pterin concentrations vary with the site of the defect. Symptoms include profound hypokiesis and other features of basal ganglia disease. Neither symptoms nor amine changes are relieved by controlling phenylalanine concentrations. Patients with dihydropteridine reductase (DHPR) deficiency accumulate dihydrobiopterins and develop secondary folate deficiency which resembles that occurring in patients with defective 5,10-methylene tetrahydrofolate reductase activity. The latter disorder is also associated writh Parkinsonisn and defective amine and pterin turnover in the and a occurs in In central nervous system, demyelinating illness both disorders.
    [Show full text]
  • Different Strategies in the Treatment of Dihydropteridine Reductase Deficiency
    Zurich Open Repository and Archive University of Zurich Main Library Strickhofstrasse 39 CH-8057 Zurich www.zora.uzh.ch Year: 1996 Different Strategies In the Treatment of Dihydropteridine Reductase Deficiency Spada, M ; Blau, N ; Meli, C ; Ferrero, G B ; de Sanctis, L ; Ferraris, S ; Ponzone, A DOI: https://doi.org/10.1515/pteridines.1996.7.3.107 Posted at the Zurich Open Repository and Archive, University of Zurich ZORA URL: https://doi.org/10.5167/uzh-155067 Journal Article Published Version Originally published at: Spada, M; Blau, N; Meli, C; Ferrero, G B; de Sanctis, L; Ferraris, S; Ponzone, A (1996). Different Strategies In the Treatment of Dihydropteridine Reductase Deficiency. Pteridines, 7(3):107-109. DOI: https://doi.org/10.1515/pteridines.1996.7.3.107 Spada et al.: Treatment of DHPR deficiency Pteridines Vol. 7, 1996, pp. 107 - 109 Different Strategies In the Treatment of Dihydropteridine Reductase Deficiency 2 l M . Spada', N. Blau , C. Meli\ G . B. rerrero', L. de Sanctis\ S. Ferraris and A. Ponzone'· 4§ IDipartimento di Scienze Pediatriche e dell'Adolcscenza, Universita'degli Studi di Torino, Italy 2Division of Clinical Chemistry, University Children's Hospital, Zurich, Switzerland 3 C linica Pediatrica, Universita'di Catania, Italy 4Facolta'di Magistero, Universita'di Messina, Italy (Received July IS, 1996) Introduction mal serum Phe levels. Despite substantial amounts of peripherally ad- Inherited deficiency of dihydropteridine reduc- ministered BH4 can be found in cerebrospinal tase (DHPR, EC 1.66.99.7) impairs the re- fluid (CSr), only some patients respond at the generation of tetrahydrobiopterin (BH 4), the es- central level to BH4 monotherapy (3,4).
    [Show full text]
  • Massive Parallel Sequencing As a New Diagnostic Approach For
    Chaiyasap et al. BMC Medical Genetics (2017) 18:102 DOI 10.1186/s12881-017-0464-x RESEARCH ARTICLE Open Access Massive parallel sequencing as a new diagnostic approach for phenylketonuria and tetrahydrobiopterin-deficiency in Thailand Pongsathorn Chaiyasap1, Chupong Ittiwut1,2, Chalurmpon Srichomthong1,2, Apiruk Sangsin3, Kanya Suphapeetiporn1,2,4* and Vorasuk Shotelersuk1,2 Abstract Background: Hyperphenylalaninemia (HPA) can be classified into phenylketonuria (PKU) which is caused by mutations in the phenylalanine hydroxylase (PAH) gene, and BH4 deficiency caused by alterations in genes involved in tetrahydrobiopterin (BH4) biosynthesis pathway. Dietary restriction of phenylalanine is considered to be the main treatment of PKU to prevent irreversible intellectual disability. However, the same dietary intervention in BH4 deficiency patients is not as effective, as BH4 is also a cofactor in many neurotransmitter syntheses. Method: We utilized next generation sequencing (NGS) technique to investigate four unrelated Thai patients with hyperphenylalaninemia. Result: We successfully identified all eight mutant alleles in PKU or BH4-deficiency associated genes including three novel mutations, one in PAH and two in PTS, thus giving a definite diagnosis to these patients. Appropriate management can then be provided. Conclusion: This study identified three novel mutations in either the PAH or PTS gene and supported the use of NGS as an alternative molecular genetic approach for definite diagnosis of hyperphenylalaninemia, thus leading to proper management of these patients in Thailand. Keywords: Next generation sequencing, Exome, Hyperphenylalaninemia, Phenylketonuria, Tetrahydrobiopterin deficiency, Newborn screening Background 120 μmol/l (2 mg/dl), the individual is considered to be Phenylketonuria (PKU) is an autosomal recessive metabolic hyperphenylalaninemia (HPA) and needs further diagnosis disorder, characterized by progressive intellectual disability, [4].
    [Show full text]
  • Blueprint Genetics Hyperphenylalaninemia Panel
    Hyperphenylalaninemia Panel Test code: ME2001 Is a 6 gene panel that includes assessment of non-coding variants. Is ideal for patients with a clinical suspicion of hyperphenylalaninaemias including hyperphenylalaninemia due to BH4 deficiency. The genes on this panel are included in the Comprehansive Metabolism Panel. About Hyperphenylalaninemia Hyperphenylalaninemias (HPA) are errors in metabolism resulting in characterics of elevated levels of phenylalanine amino acid in the blood. Phenylketonuria (PKU) results in hyperphenylalaninemia if left untreated. Elevated levels if phenylalanine will make a severe risk of intellectual disability for a child. Unborn babies with mutation in homozygous state are unaffected as mother’s circulation prevents buildup. After birth, phenylalanine-restricted diet prevents intellectual problems and the persons with homozygous mutated genotype have normal mental development. However, maternal PKU without metabolic control predisposes babies to severe mental retardation and heart defects. This is an example of a genetic disease of a baby based on mother’s genotype. Classical PKU is caused by mutations in PAH, but some 2% of all HPAs result from impaired synthesis or recycling of tetrahydrobiopterin (BH4). Causative mutations in these cases are in GCH1, PCBD1, PTS or QDPR genes. The worldwide prevalence of PKU is estimated at 1:10 000 births having, however, rather big variation in different populations. The prevalence of tetrahydrobiopterin is estimated at <1:500 000 newborns. However, in certain populations
    [Show full text]
  • Supplementary Table S4. FGA Co-Expressed Gene List in LUAD
    Supplementary Table S4. FGA co-expressed gene list in LUAD tumors Symbol R Locus Description FGG 0.919 4q28 fibrinogen gamma chain FGL1 0.635 8p22 fibrinogen-like 1 SLC7A2 0.536 8p22 solute carrier family 7 (cationic amino acid transporter, y+ system), member 2 DUSP4 0.521 8p12-p11 dual specificity phosphatase 4 HAL 0.51 12q22-q24.1histidine ammonia-lyase PDE4D 0.499 5q12 phosphodiesterase 4D, cAMP-specific FURIN 0.497 15q26.1 furin (paired basic amino acid cleaving enzyme) CPS1 0.49 2q35 carbamoyl-phosphate synthase 1, mitochondrial TESC 0.478 12q24.22 tescalcin INHA 0.465 2q35 inhibin, alpha S100P 0.461 4p16 S100 calcium binding protein P VPS37A 0.447 8p22 vacuolar protein sorting 37 homolog A (S. cerevisiae) SLC16A14 0.447 2q36.3 solute carrier family 16, member 14 PPARGC1A 0.443 4p15.1 peroxisome proliferator-activated receptor gamma, coactivator 1 alpha SIK1 0.435 21q22.3 salt-inducible kinase 1 IRS2 0.434 13q34 insulin receptor substrate 2 RND1 0.433 12q12 Rho family GTPase 1 HGD 0.433 3q13.33 homogentisate 1,2-dioxygenase PTP4A1 0.432 6q12 protein tyrosine phosphatase type IVA, member 1 C8orf4 0.428 8p11.2 chromosome 8 open reading frame 4 DDC 0.427 7p12.2 dopa decarboxylase (aromatic L-amino acid decarboxylase) TACC2 0.427 10q26 transforming, acidic coiled-coil containing protein 2 MUC13 0.422 3q21.2 mucin 13, cell surface associated C5 0.412 9q33-q34 complement component 5 NR4A2 0.412 2q22-q23 nuclear receptor subfamily 4, group A, member 2 EYS 0.411 6q12 eyes shut homolog (Drosophila) GPX2 0.406 14q24.1 glutathione peroxidase
    [Show full text]
  • Gene Transfer As a Potential Treatment for Tetralujdrobiopterin Deficient States
    Gene Transfer as a Potential Treatment for Tetralujdrobiopterin Deficient States Rickard F oxton Division of Neurochemistry Department of Molecular Neuroscience Institute of Neurology University College London Submitted November 2006 Funded by Brain Research Trust Thesis submitted for the degree of Doctor of Philosophy, University of London. I, Richard Hartas Foxton, confirm that the work presented in this thesis is my own. Where information has been derived from other sources, I confirm that this has been indicated in the thesis.' 1 UMI Number: U592813 All rights reserved INFORMATION TO ALL USERS The quality of this reproduction is dependent upon the quality of the copy submitted. In the unlikely event that the author did not send a complete manuscript and there are missing pages, these will be noted. Also, if material had to be removed, a note will indicate the deletion. Dissertation Publishing UMI U592813 Published by ProQuest LLC 2013. Copyright in the Dissertation held by the Author. Microform Edition © ProQuest LLC. All rights reserved. This work is protected against unauthorized copying under Title 17, United States Code. ProQuest LLC 789 East Eisenhower Parkway P.O. Box 1346 Ann Arbor, Ml 48106-1346 ABSTRACT Tetrahydrobiopterin (BH4) is an essential cofactor for dopamine (DA), noradrenaline (NA), serotonin and nitric oxide (NO) synthesis in the brain. Inborn errors of BH4 metabolism including GTP cyclohydrolase 1 (GTP-CH) deficiency are debilitating diseases in which BH4, DA, 5-HT and NO metabolism are impaired. Current treatment for these disorders is typically monoamine replacement +/- BH4. Whilst correction of the primary defect is the ideal, BH4 treatment is problematic as it is expensive and inefficacious.
    [Show full text]
  • Isolation and Expression of Rat Liver Sepiapterin Reductase Cdna
    Proc. Nat!. Acad. Sci. USA Vol. 87, pp. 6436-6440, August 1990 Genetics Isolation and expression of rat liver sepiapterin reductase cDNA (tetrahydrobiopterin/biopterin/pyruvoyltetrahydropterin/aromatic amino acid hydroxylase/molecular cloning) BRUCE A. CITRON*, SHELDON MILSTIEN*, JOANNE C. GUTIERREZt, ROBERT A. LEVINE, BRENDA L. YANAK*§, AND SEYMOUR KAUFMAN*¶ *Laboratory of Neurochemistry, Room 3D30, Building 36, and tLaboratory of Cell Biology, National Institute of Mental Health, National Institutes of Health, Bethesda, MD 20892; and tLaboratory of Molecular Neurobiology, Lafayette Clinic, 951 East Lafayette, Detroit, MI 48207 Contributed by Seymour Kaufman, June 7, 1990 ABSTRACT Sepiapterin reductase (7,8-dihydrobiopterin: either case, the final carbonyl reduction to form tetrahydro- NADP+ oxidoreductase, EC 1.1.1.153) catalyzes the terminal biopterin must be catalyzed by sepiapterin reductase. step in the biosynthetic pathway for tetrahydrobiopterin, the In the present study, we have screened a rat liver cDNA cofactor necessary for aromatic amino acid hydroxylation. We library with a specific antibody that reacts positively to the report here the isolation of a cDNA clone for rat liver sepia- enzyme band on Western blots (19). These clones were used pterin reductase. The cDNA has been excised from a lambda to further characterize the enzyme and to begin to elucidate vector and the DNA sequence was determined. The insert the functional sites ofthe enzymes in the tetrahydrobiopterin contains the coding sequence for at least 95% of the rat enzyme biosynthetic pathway. 11 and is fused to the Escherichia coli (3-galactosidase N-terminal segment and the lac promoter. The N-terminal region of the clone contains an extraordinarily high G+C content.
    [Show full text]
  • Biosynthesis of Tetrahydrobiopterin in Man
    J. tnher. Metab. Dis. 8 Suppl. 1 (I985) 28-33 Biosynthesis of Tetrahydrobiopterin in Man H.-CH. CURTIUS, D. HEINTEL, S. GHISLA1, TH. KUSTER, W. LEIMBACHER and A. NIEDERWIESER Division of Clinical Chemistry, Department of Pediatrics, University of Zurich, Switzerland t Department of Biology, University of Constance, POB 5560, D-7750 Constance, FRG The biosynthesis oftetrahydrobiopterin (BH4) from dihydroneopterin triphosphate (NHzP3) was studied in human liver extract. The phosphate-eliminating enzyme (PEE) was purified ~ 750-fold. The conversion of NH2P3 to BH~ was catalyzed by this enzyme in the presence of partially purified sepiapterin reductase, Mg z ÷ and NADPH. The PEE is heat stable when heated at 80 °C for 5 min. It has a molecular weight of 63 000 daltons. One possible intermediate 6-(l'-hydroxy-2'-oxopropyl)5,6,7,8-tetrahydropterin(2'-oxo-tetrahydro- pterin) was formed upon incubation of BH4 in the presence of sepiapterin reductase and NADP ÷ at pH 9.0. Reduction of this compound with NaBD4 yielded monodeutero threo and erythro-BH4, the deuterium was incorporated at the 2' position. This and the UV spectra were consistent with a 2'-oxo-tetrahydropterin structure. Dihydrofolate reductase (DHFR) catalyzed the reduction of BH2 to BH4 and was found to be specific for the pro-R-NADPH side. The sepiapterin reductase catalyzed the transfer of the pro-S hydrogen of NADPH during the reduction of sepiapterin to BHa. In the presence of crude liver extracts the conversion of NHzP3 to BH4 requires NADPH. Two deuterium atoms were incorporated from (4S-2H)NADHP in the 1' and 2' position of the BH4 side chain.
    [Show full text]
  • Natalis Information Sheet V03
    Sema4 Natalis Clinical significance of panel Sema4 has designed and validated Natalis, a supplemental newborn screening panel offered for newborns, infants, and young children. This test may be offered to parents as an addition to the state mandated newborn screening that their child received at birth. This panel includes next-generation sequencing, targeting genotyping, and multiplex ligation-dependent probe amplification in a total of 166 genes to screen for 193 conditions that have onset in infancy or early childhood and for which there is treatment or medical management that, when administered early in an infant or child’s life, will significantly improve the clinical outcome. Conditions included in this panel were curated based on criteria such as: inclusion on current state mandated newborn screening panels, onset of symptoms occurring <10 years of age, evidence of high penetrance (>80%), and availability of a treatment or improvement in life due to early intervention. Sema4 has also designed and validated a pediatric pharmacogenetic (PGx) genotyping panel as an adjunct test to the Natalis assay. This panel includes 10 genes and 41 sequence variants involved in drug response variability. The genes and variants in the PGx genotyping panel inform on more than 40 medications that can be prescribed during childhood. Currently, there is evidence supporting the clinical utility of testing for certain PGx variants for which there are genotype-directed clinical practice recommendations for selected gene/drug pairs. Approximately 95% of all individuals will carry at least one clinically actionable variant in the PGx panel. Testing methods, sensitivity, and limitations A cheek swab, saliva sample, or blood sample is provided by the child and a biological parent.
    [Show full text]