Comparison of likelihood approaches for combined segregation and linkage analysis of a complex disease and a candidate gene marker under different ascertainment schemes.

: We compared two joint likelihood approaches, with complete (L1) or without (L2) linkage disequilibrium, under different ascertainment schemes, for the genetic analysis of the disease trait and marker gene 1 in replicate 42. Joint likelihoods were computed without a correction for the selection scheme. For the different sampling schemes we have explored, our results suggest that L1 is a more powerful approach than L2 to detect major gene and covariate effects as well as to identify accurately gene x covariate interaction effects in a common and complex disease such as the Genetic Analysis Workshop 12 MG6 simulated trait.