Iran J Pediatr Original Article Apr 2013; Vol 23 (No 2), Pp: 233-236

New Single Nucleotide Deletion In the SMPD1 Gene Causes Niemann Pick Disease Type A in a Child from Southwest Iran: A Case Report

Hamid Galehdari1; Raheleh Tangestani2; Sepideh Ghasemian3

1. Department of Genetics, Shahid Chamran University, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran 2. Research Center of Thalassemia and Hemoglobinopathies, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran 3. Toxicology Research Center, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran Jan 25, 2012 Aug 01, 2012 Dec 29, 2012

Received: ; Accepted: ; Online Available: Abstract Objective: # SMPD1 Niemann Pick disease (NPD) type A (NPA: MIM 257200) is a storage disorder with an autosomal recessive inheritance and occurrs by defect of the gene encoding sphingomyelinase. Disruption of this leads to the accumulation of in brain and , which in turn causes dysfunctionMethods: or damage of tissue. We reportSMPD1 firstly a 2.5 year old boy with NPA in southwest Iran. Initially, the diagnosis was resulted on the basis of clinical symptoms. The genomic DNA of the suspected individual was subjectedSMPD1 to exon sequencing of the gene. According to the human reference sequence NM_000543.4, a novel single guanine deletion resulting in a frameshift mutation (p.Gly247Alafs*9) was observed in the gene that mightFindings be :causative for the outcome of the disease. The present report is the first molecular genetics diagnosis of the NPA in southwest Iran. The detectedConclusion: deletion in the SMPD1 gene is remarkable because of its novelty. Despite similar morbidity SGA infants exhibited higher lethal complication rates following IraniandelayedJournal meconiumof Pediatrics passage, Volume compared23 (Number to2), AGAApr 20 infants.13, Pages: 233-236

Key Words: SMPD1

Niemann Pick disease; Gene; Acid sphingomyelinase-1; Mutation

Introduction

the biochemical and molecular[2] levels with a higher incidence than NPA and NPB . Both types A and B NPD is a heterogeneous disease with variations are characterized by Acid sphingomyelinase due to molecular and clinical courses. The (ASM) deficiency that leads to excessive incidence of the disease[1] is approximately sphingomyelin accumulation[3] in all phagocytic cells

1:150 000 live births . Because of variations in and in neurons . NPB is biochemically[4] similar to pathological and clinical features of the disease, NPA, but with less severity . Normally, the NPD is classified into those with deficiency of acid enzyme activity of ASM leads to the breakdown of sphingomyelinase activity (types A and B), and sphingomyelin into [3] and phosphoryl- those with defective intracellular processing and choline in . Generally, multiple organs transporting of LDL cholesterol, which is known as such as spleen, liver, bone marrow, lymph nodes, type C. However, NPD type C (NPC) is different at lung and central nervous system are affected. * Corresponding Author; Address: Department of Genetics, Shahid Chamran University, Ahvaz, Iran E-mail: [email protected]

© 2013 by Pediatrics Center of Excellence, Children’s Medical Center,Iran J Tehran Pediatr; University Vol 23 (No of2), Medical Apr 2013 Sciences, All rights reserved. Published by: Tehran University of Medical Sciences (http://ijp.tums.ac.ir) 234 Novel mutation in the SMPD1 Gene

Case Presentation

Diagnosis can be achieved at the early childhood

with a poor prognosis. Most NPA[1,3] patients die before reaching the age of 3 years . Clinically, A 2.5 year-old male, the first born child from first NPA is distinguished by failure of thrive, cousin parents was attending our center for hepatosplenomegaly and progressive neuro- genetic counseling and genetic diagnostics. The [5] SMPD1 degeneration . At molecular genetics level, patient showed typical signs of the Niemann Pick mutations in the gene on chromosome disease, such as hepatosplenomegaly, develop- SMPD1 [6] 11p14.5 are causative for the disease . The mental delay, mental retardation, and foam cells in

gene is approximately 5 kb long and the the bone marrow, hypotonia, and th cherry red coding sequence is divided among six exons. maculae. Seizure and anorexia at 5-6 month of According to the Human Gene Mutation Database life was observed. He died as results of his illness. (www.hmdb.cf.ac.uk), more than 100 different Unfortunately, measurement of the ASM activity in the white blood cells failed and DNA test was the mutations (includingSMPD1 missense, nonsense, deletion, insertion, and splice site mutations) have only chance to establish a definite diagnosis. been reported in the gene. After obtaining informed consent, blood To date, some clinical investigations have been samples were collected from patient and his reported from Iranian patients. For instance, parents. Genomic DNA was extracted from EDTA- Motamedi et al reported a case of NPB in Iran and[7] described the clinical course of his patient . anticoagulated whole blood by standard salting Furthermore, Motamed et al reported a ten year out procedures. Selective amplification of all 6 study of liver biopsies in children's Medical Center exons was performed in a volume of 25 μl reaction in Tehran. They identified numerous patients with containing 10 pmol of each primer (TAG storage diseases. Most identified patients were Copenhagen A/S, Fruebjergvej3, Denmark) and 50ng of genomic DNA. PCR was carried out by a affected with NPD[8] and glycogen storage disease type 1 (GSD-I) . In addition, Majidzadeh et al set of designed primers using primer3out reported a case of NPD and compared clinical and software (http://frodo.wi.mit.edu/primer3/). [9] SMPD1 Properties of primers are indicated in Table 1. molecular aspects of the disease . Hoshmand et ° Temperature profile of reactions were as al presented a novel mutation in the gene ° ° ° follow: initial denaturation at 95 C for 3 min, 35 (data not published). Here, we present the first ° molecular genetics diagnosis of NPA in an cycles of 95 C for 30s, 56-60 C for 30s and 72 C individual from southwest Iran. for 45s and a final extension at 72 C for 7 min.

Table 1: SMPD1

The gene was amplified by seven primer pairs. Exon 2 was amplified exon by two separate primerPrimer pairs sequence to assist (5’tosubsequent 3‘) sequencinglength reactions Tm 1-forward 1-reverse 2A-forward GAAGCGCGACAATGCCCCGCTA 445 bp 60.5°C 2A-reverse AGATGCCACCCTCTCCATCAGGGA 2B-forward GTGTGCACTGAGCTTGGTGCACTG 493bp 60.3°C 2B-reverse GTCTGCACAGTCAGGGTCCGTG 3-forward TGCTGCCTGAGTTACAGGGCAA 1058bp 59.4°C 3-reverse GCACTAAGGACTCATGCTAGAGCA 4-forward GGCTAGACTGTGAGCTCCTTGCAG 441bp 59.1°C 4-reverse CAACAGTGACCATGAGCTGAATCC 5-forward GTTGAGCTGGAGCACCTCTG 354bp 58.8°C 5-reverse CCCACTCCATGGGACAACAG 6-forward GACAGGGTGAGTGTCTGAAGGCTG 490bp 59.4°C 6-reverse GTACACACGGTAACCTGCAAGGA ACATCGGCCTTAATCCTGGTGAG 678bp 59.6°C ACCGGATGATCTTGCCTGGTTGAA

Iran J Pediatr; Vol 23 (No 2), Apr 2013 Published by: Tehran University of Medical Sciences (http://ijp.tums.ac.ir) Galehdari H, et al 235

Fig. 1:

Chromatogram of sequencing reactions from a) affected individual, b)SMPD1 heterozygote parents, c) healthy person. The location of the novel deletion is indicated with black arrow and the position of the resulting stop codon is shown in black circle on the chromatogram. At bottom (d), partial sequence of the gene with corresponding codons is illustrated. Accordingly, the newly created stop codon is located between codons 256-257.

[10] Direct sequencing of PCR products was carried out people of Ashkenazi Jewish descent has NPA . In using ABI automated sequencer 3700 according to contrast, there is no information about frequency the manufacture’s instruction (ABI 3700, PE and distribution of different types of NPD in Iran, Applied BioSystems, Foster City, CA, USA). particularly in southwest Iran. Sequencing reactions were accomplished by the The disease refers to a group of disorders with same primers that were used for exon deficiency in lipid storage, causing accumulation of amplification. Sequence analysis was performed fats in brain and liver that lead to serious[11] damage with the software BioEdit (version 7.0.5.3). or dysfunction of mentioned tissues . However, According to the human reference sequence liver enlargement, brain damage, difficulty in NM_000543.4, a homozygous single guanine walking, speaking and learning are characteristic SMPD1 [12] deletion, c.740delG, was observed in exon 2 of the symptoms for NPA . Diagnosis of this type of

gene, which results in a premature stop disease is usually made by measuring[5] the ASM codon (CTG>TGA) between codons 256-257 activity in white blood cells . Regarding some (p.Gly247Alafs*9) (Fig 1). Apparently healthy typical symptoms, our patient was suspected to parents were heterozygous for the detected suffer of NPA. He was also referredSMPD1 to our change. They are also obligate carrier. To confirm molecular diagnostic center with the aim to find the pathogenic relevance of the detected deletion, genetic cause of the disease. The gene is

27 healthy individuals were tested. the only[6] gene considered to be associated with NPA . SMPD1 Here, we report an unreported deletion of Discussion single guanine in exon 2 of the gene, causing a truncated gene product. Exon 2 is unusually large, which encodes for 258 amino acids or approximately 44% of the entire ASM To our knowledge by intensive literature polypeptide. However, the pathogenic nature of searching, the present report demonstrates firstly the novel deletion was confirmed by screening of the molecular genetics diagnosis of the NPD in healthy individuals. southwest Iran. Approximately 1 per 40,000 Three common missense mutations account for

Iran J Pediatr; Vol 23 (No 2), Apr 2013 Published by: Tehran University of Medical Sciences (http://ijp.tums.ac.ir) 236 Novel mutation in the SMPD1 Gene

more than 90% of the mutant alleles in individuals 3. Harzer K, Rolfs A, Bauer P, et al. Niemann-Pick disease type A and B are clinically but also of Ashkenazi Jewish ancestry with NPA. But in enzymatically heterogeneous: pitfall in the contrast to the Ashkenazi Jewish population, most SMPD1 Neuropediatricslaboratory diagnosis of sphingomyelinase deficiency associated with the mutation Q292 K. affected individuals with NPA showed in previous[11] studies unique mutations in the gene . 2003;34(6):301-6. Consequently, identification of new NPA cases 4. McGovern MM, Wasserstein MP, Giugliani R, et al. A increases the probability to discover new specific Pedprospective,iatrics cross-sectional survey study of the natural history of Niemann-Pick disease type B. mutations for the given population. SMPD1 2008;122(2):e341-9. The present observations extend the mutation 5. Alizon C, Beucher AB, GourdierRev Med AL, Interneet al. Type B spectrum of the gene in NPA patients Niemann Pick disease: Clinical description of three worldwide, and can be used for the prenatal or patients in a same family. 2010; preimplatation genetic diagnosis, at least in 31(8):562-5. southwest Iran. 6. Simonaro CM, Park JH, Eliyahu E, et al. Imprinting at Amthe J Hum SMPD1 Genet locus: implications for acid sphingomyelinase-deficient Niemann-Pick disease. Conclusion 2006;78(5):865-70. 7. Motamedi MK, KhoddamiArch M, Naseri Iranian M, Medet al. Type B Niemann Pick Disease: report of case with military pattern on chest X-ray. 2005; 8 To date, there are no hopeful therapeutic (3):223-5. rudiments to cure NPA patients. Therefore, 8. Motamed F, Monajemzadeh M, Seifirad S, et al. Liver prevention seems to be more effective strategy in Storage DiseaseHepat in Mon Iran: A ten year study of liver the next pregnancy for this family and other biopsies in Children Medical Centre Hospital in Tehran-Iran. 2011;11(8):652-5. Conflictfamilies of withInterest: positive history. 9. Majidizadeh T, Dehghan Manshadi M, Rostami M, et None al. NiemannEurogene Pick disease, a clinical course and molecular findings; a case report of an Iranian patient. 2009;6(2):234-7. References 10. Wasserstein MP, Aron A, Brodie SE, et al. Acid sphingomyelinase deficiency:J Pediatr prevalence and characterization of an intermediate phenotype of Niemann-Pick disease. 2006;149(4):554-9. 1. Niemann-Pick Disease Group UK. Website providing information and support. for all types of 11. SchuchmanJ Inherit EH. TheMetab pathogenesis Dis and treatment of Niemann-Pick diseases. Available at: acid sphingomyelinase‐deficient Niemann–Pick www.niemannPick.org.uk disease. 2007;30(5):654‐63.

2. JImrie Inherit J, Metab Dasgupta Dis S, Besley GT, et al. The natural 12. McGovern MM, Aron A, Brodie SE,Neurology et al. Natural history of Niemann-Pick disease type C in the UK. history of Type A Niemann-Pick disease: possible 2007; 30(1):51-9. endpoints for therapeutic trials. 2006; 66(2):228-32.

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