As NK cell counts are significantly different between patients who had grades 2-4 acute graft-versus-host disease (GVHD) versus grades 0-1 within six months after transplantation, we examined the percentage of IFNγ-producing NK cells only in patients who had grades 0-1 GVHD after haplo-HSCT, in order to avoid such effects of GVHD. The gene discussed is IFNG; the disease is graft versus host disease.