Genotyping was performed at the Washington University MicroArray facility using Illumina’s GoldenGate assays. Six single-nucleotide polymorphisms (SNPs) were genotyped across GABRA2: rs497068, rs279871, rs279867, rs279858, rs279845, and rs279836. All SNPs were located in the linkage disequilibrium block that previously yielded evidence of association in the COGA sample (average r2 across the SNPs = 0.82, range 0.71–0.98). All SNPs were in the Hardy–Weinberg equilibrium.
