Cumulative incidence of acute GVHD grades III-IV during the first 100 days following a transplantation using an 8/8, 7/8 bidirectional MM, 7/8 GVH MM, or 7/8 HVG MM donor. Significant differences were observed between the 7/8 groups (P = .0001) and the 7/8 HVG group having a lower acute GVHD risk similar to the 8/8 group.