Molecular Genetic Diagnosis for a Family with Type I Spinal Muscular Atrophy (SMA) via Analysis of the Survival Motor Neuron (SMN) Gene

Neda M Bogari, Fareed R Bogari

Abstract

Autosomal recessive spinal muscular atrophy (SMA) is, after cystic fibrosis, the second most common fatal monogenic disorder. Depending on the clinical type, SMA causes early death or increasing disability in childhood. Here, we report a three month old Saudi girl presented with a history of coughing and respiratory distress who had previous admissions due to pneumonia. There was a positive family history of sibling death, at age 2 years, due to SMA. Genetically, we found homozygous deletions of the Survival Motor Neuron (SMN1) gene exons 7 and 8 using the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis. Thus, confirming this case clinical diagnosis with presumed SMA type I. DNA testing of patients, in whom SMA is suspected, is a highly reliable, fast, and noninvasive method. The ability to detect homozygous gene deletions in a high percentage of typical SMA patients will much improve genetic counseling and prenatal diagnosis in affected families.

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