The genome-wide meta-analysis of all four studies confirmed their associations with pulmonary arterial hypertension (rs2856830, odds ratio 1·56 [95% CI 1·42–1·71], p=7·65 × 10–20 for HLA-DPA1/DPB1; rs10103692, 1·80 [1·55–2·08], p=5·13 × 10–15 for SOX17; table 1; figure 2; appendix p 13). This evidence concerns the gene HLA-DPA1 and pulmonary arterial hypertension.