Replication of the SNPs that turned out genome-wide significant was performed in five independent samples. In each sample, an additive test was conducted, with sex and age as covariates. SNPs in each sample were checked for minor allele frequency, Hardy-Weinberg equilibrium and if imputed, for imputation quality. The evidence for replication was summarized across samples by conducting a weighted inverse variance meta-analysis. A P < 0.05 was taken as significant evidence of replication.
