As is common, we used PCA as implemented in EIGENSTRAT (Price et al., 2006) to identify the major dimensions of genetic variation in our sample of Caucasian subjects, and the 10 components (PCs) accounting for the most variance were included as covariates in our GWAS to control for any remaining population stratification (cf. Price et al., 2006). Genomic inflation statistics from genome-wide analyses were subsequently examined for evidence of meaningful residual population stratification.
