One GWS SNP was identified: rs12442183 (MAF 0.41 in EAs), which is ∼110 kb upstream of RGMA, in Yale-Penn 1 (P=4.7×10-8, n=1388). Meta-analysis of this sample with the other three samples (Yale-Penn 2 and 3, and SAGE) improved the GWS association signal (meta-P=1×10-8, n=3058) (Figure 1 and Table 1). The robust association signals around the top SNP (Figure 1) and the observed negligible inflation factor in the QQ plot (Supplementary figure 2) support the validity of the GWAS result. As noted above, the association was GWS in Yale-Penn 1 taken individually. We also observed P <0.05 in both Yale-Penn 2 and Yale-Penn 3: the risk allele T of rs12442183 was significantly correlated with increased OD criterion counts in all cohorts, except for SAGE (Table 1 and Figure 2). SAGE has little variation in OD criterion count and >50% of individuals have a criterion count of 0, yielding low power in that sample.
