For subsequent analyses, we defined a reduced set of 14,456 probes (13,643 distinct genes) selected on criteria of variance and population differentiation (see Supplementary Methods). This is smaller than our previously described set of 14925 probes (14072 genes) 19, because we removed probes with either multiple mapping positions (370) or with SNPs within them that generated false associations (99). All association analyses were performed with the 14,456 probe set corresponding to 13,643 genes.
