Impact of mismatched HLA loci on the risk of acute graft-versus-host disease (Kaplan-Meier estimates). Class I MM: 1A or 1B or 1C or 1B + 1C mismatch, but no class II mismatch in GVH direction. Class II MM: 1 DRB1 and/or 1 DQB1 mismatch, but no class I mismatch in GVH direction. For comparison, the outcomes after transplantation from HLA-identical siblings (ISDs) and HLA-matched unrelated donors (MUDs) are also shown. ▴ indicated MFD-MM II (n = 21); ⋄, MFD-MM I (n = 41); ▿, MUD (n = 101); □, ISD (n = 138); and •, MFD-no MM (n = 16).