Covariates in linkage analysis using sibling and cousin pairs

Using simulated data from GAW 12, problem 2, we further develop a novel tec hnique to detect and use significant covariates in linkage analysis. The me thod, first introduced by Rice et al. [Genet Epidemiol 17(Suppl. 1):S691-5, 1999], uses logistic regression to model perturbation in sharing as a func tion of covariate levels. The original method allows use of all sib pairs ( concordant affected, concordant unaffected, and discordant). Here we extend this method to include cousin pairs in analysis. (C) 2001 Wiley-Liss, Inc.