We also employed the Bayesian fine-mapping method implemented in FINEMAP20 to infer the most likely number of distinct causal variants driving our GWAS results. FINEMAP was based on 255 regions determined by the LD clumping procedure (Supplementary Table 11e), after merging clumps if their boundaries physically overlapped and excluding the extended MHC region (Methods). For regions predicted to contain 3 or fewer causal variants (N=249; Figure 1; Supplementary Tables 11a, 11b), we extracted from FINEMAP the posterior probabilities (PP) of being causal for every SNP across the region, and constructed credible sets of SNPs that cumulatively capture 95% of the regional PP (Supplementary Note).
