Genotyping of individuals was performed using the Illumina MEGEX array. Genotypes were filtered for SNP and individual call rates, sex discrepancies and excessive heterozygosity using PLINK. Imputation was conducted using the Michigan Imputation Server based on the Haplotype Reference Consortium reference panel. PCA using FlashPCA2 (ref. 87) combined with CEU, YRI and CHB reference sets from the 1000 Genomes Project phase 3 was conducted to determine participants of AFR and EUR ancestry. One individual from each pair of related individuals was removed (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\hat{\mathrm{p}}}$$\end{document}p^ > 0.2). This resulted in 12,384 AFR and 66,903 EUR individuals for analysis.
