10-6. In addition, we looked for regions where there were multiple SNPs with low p-values (p < 1 × 10-4) with close physical proximity to one another (i.e., within 100kb). We report two regions that contain 5 SNPs that meet this criterion. Among EA, we report NAP5 (top SNP is rs10193871, p = 9.8 × 10-6), and among AA, we report an intergenic region about 300kb upstream of NTRK2 (top SNP is rs2769605, p = 4.5 × 10-5). When the EA and AA groups were combined, the most significant SNP was rs4825220 in Xq27.1, p = 2.6 × 10-7, which does not lie near a known gene. We also show Q-Q plots for each analysis (Figure S1). Within AA and EA samples, overall p-value inflation was low. However, we observed high levels of inflation when we combined the EA and AA datasets. This is due to the difference in case-control ratios between the studies, which artificially induces population stratification. Correcting for admixture using either LAMP or MDS covariates effectively removed this stratification. However, using the genomic control method to adjust the p-values overcorrected the association (Table 1).
