Abstract
Introduction: Spinal muscular atrophy (SMA) is an autosomal recessive neuromuscular disorder with an incidence of 1 in 6000 to 1 in 10,000 live births. It is characterized by degeneration of the anterior horn cells of the spinal cord, leading to progressive symmetrical proximal muscle weakness and atrophy. About 95-98% of patients have a homozygous deletion of exons 7 and 8 in the telomeric copy of the survival motor neuron 1 gene ( SMN1 ). Another 2-5% are compound heterozygotes for deletion of exons 7 and 8 of SMN1 and a point mutation in SMN1 gene. The clinical and genetic pattern of SMA has not previously been reported in Sri Lanka. Genetic testing for SMA was introduced in Sri Lanka in 2007 since when 39 patients clinically suspected of SMA were referred for testing. Of these, 7 (18%) had homozygous deletions in exons 7 and 8. We describe the clinical and genetic features of these 7 SMA patients.
Highlights
Spinal muscular atrophy (SMA) is an autosomal recessive neuromuscular disorder with an incidence of 1 in 6000 to 1 in 10,000 live births[1]
Of the 109 prenatal diagnoses performed, 29 fetuses were diagnosed to be at more than 99% risk of developing the disease, while in 7 additional pregnancies no exact prediction could be made due to a recombination event in 1 parental haplotype
The phenotypic heterogeneity of SMA is striking with clinical severity ranging from SMA types 1 to 4
Summary
Shree R Banstola[1], Nirmala D Sirisena[2], Dulika S Sumathipala2, *Vajira H W Dissanayake[3].
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