Event-free survival of patients receiving parental donor haploidentical HSCT for acute leukemia. Stratified by donor sex (A, mother donors, N = 47; father donors, N = 71) and by both donor sex and NK alloreactivity (B, NK alloreactive mother donor transplantation, N = 21; NK nonalloreactive mother donor transplantation, N = 20; NK alloreactive father donor transplantation, N = 19; NK nonalloreactive father donor transplantation, N = 40).