Semiparametric Quantitative-Trait-Locus Mapping: II. on Censored Age-at-Onset

In genetic studies, the variation in genotypes may not only affect different inheritance patterns in qualitative traits, but may also affect the age-at-onset as quantitative trait. In this article, we use standard cross designs, such as backcross or F2, to propose some hazard regression models, namely, the additive hazards model in quantitative trait loci mapping for age-at-onset, although the developed method can be extended to more complex designs. With additive invariance of the additive hazards models in mixture probabilities, we develop flexible semiparametric methodologies in interval regression mapping without heavy computing burden. A recently developed multiple comparison procedures is adapted to identify the QTL in dense maps. The proposed methodologies will be evaluated by simulation studies and demonstrated in an actual data analysis of forest tree growth.