Becker's allelic model to explain unusual pedigrees with spinal muscular atrophy.
D000483:Alleles; D005260:Female; D006801:Humans; D008297:Male; D008957:Models, Genetic; D009133:Muscular Atrophy / Q000235:genetics*; D010375:Pedigree; D013122:Spinal Diseases / Q000235:genetics*