title: Counseling for dominant traits: a correction for the ascertainment bias due to referral for analysis.
abstract: Genetic heterogeneity complicates genetic counseling because the correct mode of inheritance must be determined independently for each pedigree. When autosomal and X-linked dominants inheritance mechanisms are known, as for example with retinitis pigmentosa, then only families where male-to-male transmission is observed may be readily counseled. The other pedigrees may be autosomal but lack male-to-male transmission due to chance segregation. Since only the pedigrees without male-to-male transmission are analyzed for their mode of inheritance, there is an ascertainment bias which must be corrected when evaluating the likelihood of the two inheritance patterns. A method to correct for this bias using conditional likelihoods is given, along with examples to demonstrate its use.
mesh_terms: D005260:Female; D005799:Genes, Dominant; D005817:Genetic Counseling; D006801:Humans; D008297:Male; D010375:Pedigree; D013223:Statistics as Topic