MODELING THE ROLE OF 2 SUSCEPTIBILITY LOCI BY THE MASC METHOD

Two susceptibility genes, in linkage disequilibrium with alleles of th e markers D1G31 and D5G23, have been identified for the disease in the simulated data set of Problem 1. Here we apply the MASC (marker assoc iation segregation chi-square) method to model the joint effect of the se two genes, by testing two-locus models. The model we obtain, that i s the most parsimonious and that best fits the data, corresponds to a direct involvement of the alleles D1G31-8 and D5G23-7, with a nonmulti plicative effect of the two alleles. This was indeed assumed in the tr ue model used for simulating the data. (C) 1995 Wiley-Liss, Inc.