Prior to QC, the genotype data were pooled with the preQC data from GWAS1. QC was then performed on the pooled data. The following criteria were applied: sample call rate (CR) >=0.98; and conformity between reported sex and genotypic sex. In the case of duplicates or cryptic relatedness (IBS across autosomal markers >=1.6), the sample with the lower call rate was removed. Outliers were identified using PCA.
