Autosomal dominant inheritance

Abstract Well over 4000 disorders and polymorphic systems showing definite or probable autosomal dominant inheritance have been documented (McKusick, 1997). As the name implies, these conditions are determined by genes at autosomal loci and are manifest in the heterozygote. The provision of risks for disorders showing autosomal dominant inheritance is straightforward if there is a clear family history and the disorder in question is characterized by complete penetrance, consistent expression, and a reliable means of diagnosing heterozygotes. The risk to each child of an affected individual will be 50 per cent, whereas the child of an unaffected family member will be at negligible risk, or, to be more precise, twice the mutation rate(µ).