Apparent gene conversions involving the SMN gene in the region of the spinal muscular atrophy locus on chromosome 5
- Univ. of Groningen (Netherlands); and others
The survival motor neuron (SMN) gene has been described as a determining gene for spinal muscular atrophy (SMA). SMN has a closely flanking, nearly identical copy ({sup C}BCD541). Gene and copy gene can be discriminated by sequence differences in exons 7 and 8. The large majority of SMA patients show homozygous deletions of at least exons 7 and 8 of the SMN gene. A minority of patients show absence of SMN exon 7 but retention of exon 8. This is explained by results of our present analysis of 13 such patients providing evidence for apparent gene-conversion events between SMN and the centromeric copy gene. Instead of applying a separate analysis for absence or presence of SMN exons 7 and 8, we used a contiguous PCR from intron 6 to exon 8. In every case we found a chimeric gene with a fusion of exon 7 of the copy gene and exon 8 of SMN and absence of a normal SMN gene. Similar events, including the fusion counterpart, were observed in a group of controls, although in the presence of a normal SMN gene. Chimeric genes as the result of fusions of parts of SMN and {sup C}BCD541 apparently are far from rare and may partly explain the frequently observed SMN deletions in SMA patients. 23 refs., 4 figs.
- OSTI ID:
- 476753
- Journal Information:
- American Journal of Human Genetics, Vol. 59, Issue 4; Other Information: PBD: Oct 1996
- Country of Publication:
- United States
- Language:
- English
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