Power of selective genotyping in genetic association analyses of quantitative traits

A power calculation is described in which the power of selective genotyping in genetic-association studies of quantitative traits is evaluated. The me thod of selective genotyping implies the selection of the extremely high an d low scoring individuals from the continuous distribution of a quantitativ e trait. The selected individuals are genotyped and association is tested. In the power calculation the following parameters are varied: total sample size of the phenotyped roup (1000, 1500, 2000); selection of extremely high and low scoring individuals (2.5%, 5%, 10%); allele frequency of the risk increasing allele (0.10 to 0.90); mode of inheritance and proportion of var iance explained by the quantitative trait locus (QTL) (<(omega)over bar>(2) = 0.01, 0.05, 0.10). We conclude that the method of selective genotyping i s a powerful method to detect association for a quantitative trait.