Identification of susceptibility loci contributing to a complex disease using conventional segregation, linkage, and association methods.

We set out to apply conventional analytic methods to a GAW data set of nuclear families with an oligogenic disease that has a population prevalence of 0.023. We chose methods generally applied to disorders with at least one major gene. Our approaches included: 1) complex segregation analysis under two models of ascertainment, 2) linkage analysis assuming either a single-locus trait with possible genetic heterogeneity or a two-locus trait, and 3) allelic association studies using both a case/control approach and the haplotype relative risk (HRR) test. The association study was the only analysis of the three that provided evidence for genes playing a role in the etiology of this disorder.