Genetics of acheiropodia (the handless and footless families of Brazil). VI. Formal genetic analysis.
A genetic analysis is presented of data from 22 Brazilian sibships with cases of acheiropodia (the handless and footless families of Brazil). Segregation  analysis performed using a 16K CDC 3100 computer showed a segregation frequency of .245 +/- .040, which is close to the expected value of .25. No sporadic cases were detected. The ascertainment of the probands was through multiple incomplete selection (pi = .55 +/- .07). The data are consistent with the hypothesis of an extremely rare autosomal recessive gene as the etiological factor in acheiropodia. Prevalence is estimated as 29 +/- 4, which is the same as the number of high risk cases; gene frequency equals .0009 +/- .0005, and the incidence at birth is 4 times 10(-6) by the indirect method or 7 times 10(-6) by the direct method. The frequency of heterozygotes at birth is assumed to be 0.18% (450 times the frequency of affected). Population size is approximately 10 million, and the number of founders on a unique-mutation hypothesis is estimated as about 500. All these estimates are first approximations and must be accepted with caution.
D000015:Abnormalities, Multiple; D001938:Brazil; D002869:Chromosome Aberrations / Q000453:epidemiology*; D025063:Chromosome Disorders; D005260:Female; D005532:Foot Deformities, Congenital; D005542:Forearm / Q000002:abnormalities*; D005787:Gene Frequency; D005808:Genes, Recessive; D006228:Hand Deformities, Congenital; D006579:Heterozygote; D006720:Homozygote; D006801:Humans; D008297:Male; D010375:Pedigree