Conversely, in HSCT using MUD, having a missing KIR ligand was as follows: (1) predictive for increased relapse risk in one study involving AML patients transplanted in HLA-mismatched pairs [78]; (2) associated with reduced RI in patients transplanted with KIR2DS1+/C1+ donors [79] or KIR3DL1+/S1+ grafts [80]; and (3) associated with reduced NRM and acute GvHD in patients transplanted from KIR3DS1+ donors, with no impact on RI [81]. The gene discussed is KIR3DL1; the disease is acute graft versus host disease.