THE USE OF FIXED EFFECT MODELS AND MIXED MODELS TO ESTIMATE SINGLE GENE ASSOCIATED EFFECTS ON POLYGENIC TRAITS

Single gene associated effects on polygenic traits may often be confounded with the effects of a non-random genetic relationship between individuals sharing a particular allele of the investigated gene. Two different statistical models are suggested to separate the single gene associated effects from the remaining additive genotype: a fixed effect model with ancestor variables and a mixed model with random effects of the additive genotypes of the individual animals (individual animal model). The use of the models is illustrated by an example from an experiment with the chicken major histocompatibility complex (MHC) gene region.