A p-value of 5.0×10−8 was used as a threshold for GWS. Results were not adjusted for testing in two populations because we tested three distinct a priori hypotheses: (1) SNPs are associated with OD and related traits in AAs, (2) SNPs are associated with OD and related traits in EAs, and (3) associations are evident with the same SNPs in AAs and EAs (in meta-analysis). Results were not adjusted for testing two phenotypes, as the rank order correlation between the symptom count and case-control variables is 1.0 (that is, no affected subject can have a lower symptom count than a control), and the point-biserial correlation is 0.95.
