Because of possible admixture concerns in the AA sample, we re-analyzed the AA sample using the first two principal components from the EIGENSTRAT analysis as added covariates. Comparing these results to those in Table 2, the 3 top-ranked SNPs in the AA sample (one each from CHRNG, CHRNA7 and CHRNA10) were essentially unchanged (p = 0.0017, 0.0025 and 0.014 respectively). We conclude that these signals are unlikely to be population stratification artifacts.
