Clinical and molecular characterization of patients with gross hypotonia and impaired lower motor neuron function.

Spinal muscular atrophy (SMA) represents the second most common fatal autosomal recessive disorder after cystic fibrosis. Due to the high carrier frequency, the burden of this genetic disorder is very heavy in developing countries like India. The aim was to study the clinical and molecular characteristics of patients suspected with SMA. It was a cross sectional study of 105 cases from January 2008 to August 2012. Patients demographic and presenting features and PCR findings were noted. 65 (62%) cases had a confirmed diagnosis of SMA. Werdnig Hoffman disease (SMA type I) was the commonest variant seen in 34 (52.3%) children. Molecular analysis demonstrated deletion of both exon 7 and 8 of SMN1 gene in 83.1% of cases.