PROBABILITIES OF IDENTITY-BY-DESCENT PATTERNS IN SIBSHIPS WHEN THE PARENTS ARE NOT GENOTYPED

An assumption-free algorithm has been applied to compute the probabili ties of all possible identity-by-descent (IBD) configurations when the parents have not been genotyped. These probabilities can be used to d etermine the amount of information that a particular sibship will brin g to a nonparametric linkage analysis. It is shown that the number ofp ossible configurations can be extremely large even when the markers ar e closely spaced and are rather polymorphic. Further, it is not always possible to reduce this number to a manageable one simply by consider ation of the relative probabilities of the configurations. (C) 1997 Wi ley-Liss, Inc.