title: Unusual pedigree patterns in seven families with spinal muscular atrophy; further evidence for the allelic model hypothesis.
abstract: Clinical and genetic findings are presented in 18 patients, from 7 pedigrees with different types of spinal muscular atrophy (SMA). The SMA diagnosis was based on EMG and muscle biopsy findings. All 7 pedigrees show an unusual genetic pattern, not consistent with simple autosomal recessive inheritance. Furthermore, in 6 of the 7 pedigrees different types of SMA were present within each pedigree. Our findings can be explained by an extension of a multiple alleles hypothesis originally described by Becker in 1964.
mesh_terms: D000483:Alleles; D005260:Female; D005787:Gene Frequency; D005808:Genes, Recessive; D006801:Humans; D008297:Male; D008957:Models, Genetic; D009133:Muscular Atrophy / Q000145:classification / Q000235:genetics*; D010375:Pedigree