Clinico-epidemiologic characteristics of spinal muscular atrophy among Egyptians

Spinal muscular atrophy (SMA) is characterized by progressive hypotonia and muscular weakness because of progressive degeneration of alpha motor neuron from anterior horn cells in the spinal cord. It is inherited by an autosomal recessive pattern. The precise frequency of SMA in Egypt has not been determined. We tried to estimate the frequency, clinical and molecular characteristics of SMA in Egypt. The study included all patients with SMA attended the Pediatric Hospital, Ain-Shams University during the period (year 1966–2009). The study included 117 patients with SMA out of 660,280 patients attending the Pediatric Hospital. Patients selection was based on clinical examination, CPK, EMG, nerve conduction velocity, histopathology and molecular diagnosis. Frequency of SMA was 17.7/100,000, which is considered high. Type I was the commonest type (60.6%), followed by type II (26.79%), and type III (8.8%). Consanguinity was reported in 45.5 and family history in 47.8% of patients. Molecular study was done and 54.5% of patients (types I and II) have homozygous deletion of exon 7, 36.3% of whom had also homozygous deletion of exon 8 of SMN1 gene which is considered lower than that reported in other countries. SMA is more prevalent in Egypt than in many other countries. Forty-five percent of patients were chromosome 5-unlinked. We should continue to search for other mutation in Egypt to facilitate detection of carriers and prenatal diagnosis.