We used the Haseman-Elston sib-pair test to screen for linkage of mark
ers to genes for disease susceptibility in the simulated data as given
in Problem 2 of GAW9. We applied the analysis to the underlying quant
itative liability trait (Q1), other covariates of Q1 (Q2-Q4), and the
dichotomous affection status trait. In addition, we analyzed the resid
ual Q1 after adjusting for the covariates. Using the sib-pair linkage
test, we identified a large region of chromosome 5 affecting the resid
ual value of Q1, a region of chromosome 2 affecting Q3, and a region o
f chromosome 1 possibly affecting Q2. The analysis of the dichotomous
traits did not reveal any regions to be significant. This is likely to
be due to lack of information since the families were not selected th
rough affected probands. (C) 1995 Wiley-Liss, Inc.