reduction of the trait dimension. In MV-PLINK the association between a set of traits and a genetic variant is assessed using canonical correlation analysis. Specifically, the linear combination of traits that maximizes the covariance between the genetic variant and all traits is extracted. PCHAT is based on extracting the principal component of heritability that is the optimal linear combination of the traits from a heritability point of view [4]. In TATES [15], the observed correlation structure between the traits is taken into account in the meta-analysis approach.
