A CHROMOSOME-BASED METHOD TO INFER IBD SCORES FOR MISSING AND AMBIGUOUS MARKERS

We propose a probability model to impute missing identical-by-descent (IBD) vectors for linkage analysis, when adjacent marker loci are type d and interference is estimable. A chromosome-based IBD distribution, conditioned on available marker data, is computed using a fast algorit hm to estimate the joint probability of genes IBD at several equally s paced linked loci. Weighted IBD vectors are then used in various test statistics for linkage analysis. As an example, we analyzed the 18 aff ected sib pairs in the GAW9 Problem 1 data set using Risch's led-score test. (C) 1995 Wiley-Liss, Inc.