Manhattan plots of the association between SNPs and stable warfarin dose after pooling 6 African ancestry cohorts in a meta-analysis (n = 1504 participants). Individual GWAS analyses were undertaken using logarithm transformed stable warfarin dose, adjusted for age, sex, weight, target INR range, simvastatin/amiodarone status, and either the first 10 principal components of genetic ancestry or the proportion of the specific ancestry per chromosome by frequentist association testing assuming an additive model of inheritance before being pooled using METAL or MR-MEGA. (A) METAL meta-analysis with standard GWAS (242 GWAS-significant SNPs [3 genomic loci] and a genomic inflation factor of 1.023). (B) METAL meta-analysis with GWAS using African ancestry tracts (181 GWAS-significant SNPs [3 genomic loci] and a genomic inflation factor of 1.027). (C) MR-MEGA meta-analysis with standard GWAS (119 GWAS-significant SNPs [4 genomic loci] and a genomic inflation factor of 1.000). The red horizontal lines represent the genome-wide (5 × 10⁻⁸) significance threshold.