Molecular analysis of SMN1 and NAIP genes in Egyptian patients with spinal muscular atrophy.

Objectives: The aim of this study is to provide preliminary molecular data on spinal muscular atrophy in Egyptian patients thus facilitating a rapid and conventional molecular assay for accurate diagnosis of SMA.

Background: Childhood spinal muscular atrophy (SMA) is one of the most common autosomal recessive disorders. It is characterized by symmetrical muscle weakness and atrophy of limbs and trunk. At least four SMA related genes have been identified [survival motor neuron (SMN), neuronal apoptosis inhibitory protein (NAIP), the gene encoding the transcriptional factor p44 and H4F5 gene].

Methods: Homozygous absence of exons 7 and 8 of the SMN1 gene was detected using PCR-SSCP analysis, while NAIP gene deletion was detected using multiplex PCR-agarose gel electrophoresis.

Results: Homozygous absence of SMN1 exons 7 and 8, or exon 7 only, was found in 80% of patients. Of those patients, 45% were also deleted for NAIP exon 5.

Conclusion: The molecular basis of SMA in Egyptian patients has a similar pattern to that reported in most populations, but a larger study is recommended for more comprehensive characterization (Tab. 1, Fig. 2, Ref. 33).