Analysis of SMN1 gene mutations in 78 patients with spinal muscular atrophy

Abstract

To explore the significance of SMN1 gene mutations among patients with spinal muscular atrophy (SMA) and the value of multiplex ligation dependent probe amplification (MLPA) for its diagnosis. Potential mutations of the SMN1 gene were detected among 78 SMA patients with a MLPA assay. Homozygous deletion of SMN1 exons 7 and 8 was detected in 70 (89.7%) of all patients. Homozygous deletion of exons 7 and heterozygous deletion of exon 8 was detected in 3 patients (3.8%). Homozygous deletion of SMN1 exons 7 alone was detected in 3 patients (3.8%). Heterozygous deletion of SMN1 exons 7 and 8 was detected in 2 patients (2.6%). For 77 of the patients, both parents were found to carry heterozygous deletion of the SMN1 gene, which was consistent with the recessive inheritance of SMA. One patient with SMA type I was found to be rather rare. The patient was found to carry homozygous deletion of SMN1 exons 7 and 8, for which her mother was heterozygous, while no mutation was found in her father. Homozygous deletion of the SMN1 gene have been detected in more than 95% of SMA patients. No homozygous deletion of exon 8 has been found. Homozygous deletion of exon 7 is more significant in the pathogenesis of SMA.