We applied linkage analysis with a sib-pair method, which also takes i
nto account information on unaffected siblings, and family-based metho
ds of association analysis to determine the disease affecting loci in
Problem 1. Whereas the first two disease loci were correctly identifie
d by association analysis, the sib-pair linkage method failed to detec
t the disease loci 3 and 4. We therefore determined the data structure
and sample size necessary for demonstrating linkage to these loci. (C
) 1995 Wiley-Liss, Inc.