title: Incidence, prevalence, and gene frequency studies of chronic childhood spinal muscular atrophy.
abstract: A total population study of chronic childhood spinal muscular atrophy (arrested Werdnig-Hoffmann disease, Kugelberg-Welander disease, SMA type II and III) was undertaken in north-east England to establish gene and carrier frequencies, incidence, and prevalence. The incidence of this disease was 1 in 24 100 live births. Prevalence was 1.20 per 100,000 of the general population. A technique for estimating an autosomal recessive gene frequency in the known presence of dominant new mutations (or phenocopies), using data from a segregation analysis, is described. Gene frequency was in the range (0.00451 to 0.00659 (95% confidence limits), with a working estimate of 0.0055. Carrier rates for the autosomal recessive gene concerned were 1 in 76 to 1 in 111 (95%) confidence limits), with a working estimate of 1 in 90 for genetic counselling purposes.
mesh_terms: D002675:Child, Preschool; D004739:England; D005260:Female; D005787:Gene Frequency; D005808:Genes, Recessive; D006580:Genetic Carrier Screening; D006801:Humans; D008297:Male; D009133:Muscular Atrophy / Q000453:epidemiology / Q000235:genetics*; D012737:Sex Factors