Most of the top-ranked findings were population specific (Tables 1 and 2; Table S3 in Supplement 2). The only GWS association that was specific to EAs was for the chromosome 7 SNP rs13225753. This SNP (at p = 3.48 × 10−8) and two other SNPs nearby with similar p values, were tested in the adjusted (for substance use disorder criteria) ordinal model (regional Manhattan plot; Figure 3A). The gene mapped closest to this region is CACNA2D1, calcium channel, voltage-dependent, alpha 2/delta subunit 1, which encodes a component of a voltage-dependent calcium channel.
