With respect to recipients with HLA-A, -B, -C, -DRB1, or -DPB1 locus mismatches, the risk of acute GVHD (III-IV) was significantly higher, with hazard ratios of 1.40 (95% CI, 1.28 to 1.54; P < .001), 1.42 (95% CI, 1.24 to 1.62; P < .001), 1.50 (95% CI, 1.33 to 1.69; P < .001; I2 = 58.5%), 1.26 (95% CI, 1.14 to 1.40; P < .001) and 1.24 (95% CI, 1.16 to 1.33), respectively, as compared to controls (Figure 3). The gene discussed is HLA-DRB1; the disease is acute graft versus host disease.