Response to Shen et al.

To the Editor: We recently applied a principal component (PC)-based population differentiation test for selection on 54,734 European Americans from the Genetic Epidemiology Research on Adult Health and Aging (GERA) dataset to identify three new genome-wide-significant signals of selection, including a signal at the coding SNP rs1229984 in ADH1B (MIM: 103720). This latter signal was independent of a previous selection signal involving a different ADH1B haplotype in East Asians.1 Shen et al. have raised the interesting question of whether the new signal of selection might derive from selection that occurred in West Asia rather than in European populations.