Calculating genetic risk figures using a programmable pocket calculator

Summary In autosomal irregular dominant as well as in sex-linked recessive inheritance, heterozygosity probabilities for up to six or eight pedigree members with unknown genotype can easily be calculated using a programmable pocket calculator. The application of the underlying combinatorial programs is explained by means of two relevant examples. Genetic counsellors without a computer at hand are provided with a simple and accurate method for calculating genetic risk figures taking into account pedigree data, incidence and/or mutation rate, reproductive fitness, as well as penetrance or results of heterozygosity tests of the disease in question.