HLA-DRB1 and Parkinson disease: The European meta‐analysis (14,650 PD cases and 1,288,625 controls) revealed the most significant associations at His13 in HLA‐DRβ1 (P = 2.3 × 10−14; Fig 2e) as well as its tagged SNP in strong LD (rs3104413; P = 1.3 × 10−16; r2 = 0.97).