Molecular Genetic Analysis of Survival Motor Neuron Gene in 460 Turkish Cases with Suspicious Spinal Muscular Atrophy Disease

How to Cite This Article: Rashnonejad A, Onay H, Atik T, Atan Sahin O, Gokben S, Tekgul H, Ozkinay F. Molecular Genetic Analysis of Survival Motor Neuron Gene in 460 Turkish Cases with Suspicious Spinal Muscular Atrophy Disease. Iran J Child Neurol. Autumn 2016; 10(4):30-35.AbstractObjectiveTo describe 12 yr experience of molecular genetic diagnosis of Spinal Muscular Atrophy (SMA) in 460 cases of Turkish patients. Materials & MethodsA retrospective analysis was performed on data from 460 cases, referred to Medical Genetics Laboratory, Ege University’s Hospital, Izmir, Turkey, prediagnosed as SMA or with family history of SMA between 2003 and 2014.The PCR-restriction fragment length polymorphism (RFLP) and the Multiplex ligation–dependent probe amplification (MLPA) analysis were performed to detect the survival motor neuron (SMN)1 deletions and to estimate SMN1 and SMN2 gene copy numbers. ResultsUsing PCR-RFLP test, 159 of 324 postnatal and 18 of 77 prenatal cases were detected to have SMN1 deletions. From positive samples, 88.13% had a homozygous deletion in both exon 7 and exon 8 of SMN1. Using MLPA, 54.5% of families revealed heterozygous deletions of SMN1, and 2 or 3 copies of SMN2, suggesting a healthy SMA carrier. Among patients referred for SMA testing, the annual percentage of patients diagnosed as SMA has decreased gradually from 90.62% (2003) down to 20.83% (2014). ConclusionAlthough PCR-RFLP method is a reliable test for SMA screening, MLPA is a necessary additional test and provide relevant data for genetic counseling of families having previously affected child. The gradual decrease in the percentage of patients molecularly diagnosed as SMA shows that clinicians have begun to use genetic tests in the differential diagnosis of muscular atrophies. Cost and availability of these genetic tests has greatly attributed to their use.   References1. Brichta L, Holker I, Haug K, Klockgether T, Wirth B. In vivo activation of SMN in spinal muscular atrophy carriers and patients treated with valprotae. Ann Neurol 2006;59:970-5.2. Prior TW, Krainer AR, Hua Y, Swoboda KJ, Snyder PC, Bridgeman SJ, et al. A positive modifier of spinal muscular atrophy in the SMN2 gene. Am J Hum Genet 2009;85:408-13.3. 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Prenatal prediction of spinal muscular atrophy. Experience with linkage studies and consequences of present SMN deletion analysis. Eur J Hum Genet 1996;4:231-6.15. Miskovic M, Lalic T, Radivojevic D, Cirkovic S, Ostojic S, Guc-Scekic M. Ten years of experience in molecular prenatal diagnosis and carrier testing for spinal muscular atrophy among families from Serbia. Int J Gynaecol Obstet 2014;124:55-8.16. Mailman MD, Heinz JW, Papp AC, Snyder PJ, Sedra MS, Burghes AHM, Wirth B, Prior TW. Molecular analysis of spinal muscular atrophy and modification of the phenotype by SMN2. Genet Med 2002;4:20–26.17. Ogino S, Leonard DG, Rennert H, Ewens WJ, Wilson RB. Genetic risk assessment in carrier testing for spinal muscular atrophy. Am J Med Genet 2002;110:301-7.18. Wirth B. An update on the mutation spectrum of the survival motor neuron gene (SMN1) in autosomal recessive spinal muscular atrophy (SMA). Hum Mutat 2000;15:228–37

Loss of the BMP Antagonist, SMOC-1, Causes Ophthalmo-Acromelic (Waardenburg Anophthalmia) Syndrome in Humans and Mice

Ophthalmo-acromelic syndrome (OAS), also known as Waardenburg Anophthalmia syndrome, is defined by the combination of eye malformations, most commonly bilateral anophthalmia, with post-axial oligosyndactyly. Homozygosity mapping and subsequent targeted mutation analysis of a locus on 14q24.2 identified homozygous mutations in SMOC1 (SPARC-related modular calcium binding 1) in eight unrelated families. Four of these mutations are nonsense, two frame-shift, and two missense. The missense mutations are both in the second Thyroglobulin Type-1 (Tg1) domain of the protein. The orthologous gene in the mouse, Smoc1, shows site- and stage-specific expression during eye, limb, craniofacial, and somite development. We also report a targeted pre-conditional gene-trap mutation of Smoc1 (Smoc1tm1a) that reduces mRNA to ∼10% of wild-type levels. This gene-trap results in highly penetrant hindlimb post-axial oligosyndactyly in homozygous mutant animals (Smoc1tm1a/tm1a). Eye malformations, most commonly coloboma, and cleft palate occur in a significant proportion of Smoc1tm1a/tm1a embryos and pups. Thus partial loss of Smoc-1 results in a convincing phenocopy of the human disease. SMOC-1 is one of the two mammalian paralogs of Drosophila Pentagone, an inhibitor of decapentaplegic. The orthologous gene in Xenopus laevis, Smoc-1, also functions as a Bone Morphogenic Protein (BMP) antagonist in early embryogenesis. Loss of BMP antagonism during mammalian development provides a plausible explanation for both the limb and eye phenotype in humans and mice

Two cases of macrocephaly and immune deficiency

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First Genetic Screening for Maternal Uniparental Disomy of Chromosome 7 in Turkish Silver-Russell Syndrome Patients

Objective: Silver–Russell syndrome (SRS) is a clinically and genetically heterogeneous syndrome which is characterized by severe intrauterine and postnatal growth retardation, and typical characteristic facial dysmorphisms. It has been associated with maternal uniparental disomy (UPD) for chromosome 7 and hypomethylation of imprinting control region 1 (IGF2/H19) in 11p15. UPD refers to the situation in which both copies of a chromosome pair have originated from one parent. UPD can be presented both as partial heterodisomy and isodisomy. The aim of this study was to determine the maternal UPD7 (matUPD7) in 13 Turkish SRS patients. Methods: Genotyping for matUPD7 was performed with microsatellite markers by polymerase chain reaction. Findings: The maternal UPD7 including the entire chromosome was identified in 1/13 (7.6 %) of individuals within SRS patients. There were no significant differences between clinical features of matUPD7 case and other SRS cases except congenital heart defects. Conclusion: It is often difficult to establish diagnosis of a child with intrauterine growth retardation (IUGR), growth failure and dysmorphic features. Thus, screening for matUPD7 in IUGR children with growth failure and mild SRS features might be a valuable diagnostic tool

Molecular Genetic Diagnosis and Research of Candidate Genes by Targeted Next Generation Sequence Analysis and Whole Exome Sequencing Method in Monogenic Diabetes: MODY-TURK Project

[No Abstract Available

Does Mannose-Binding Lectin Gene Polymorphism in Pediatric Patients Undergoing Peritoneal Dialysis Cause Susceptibility to the Development of Peritonitis?

Objective: This study aims to investigate the relationship between peritonitis attacks and mannose-binding lectin (MBL) gene polymorphism in patients undergoing peritoneal dialysis