Computing probabilities of homozygosity by descent

A person is autozygous at a locus if the person inherits the same allele twice identical by descent along two distinct paths from the same ancestor. Autozygosity is a common cause of recessive diseases in inbred populations. Homozygosity mapping uses this fact to locate the genes that cause recessive diseases. The probability of autozygosity can be used to estimate the probability of a true positive and of a false positive in homozygosity mapping. Thompson [1994] and Guo [1997] therefore studied the problem of computing the prior, unconditional (multilocus) probability of autozygosity (MPA).