In Haplo-PTCy-transplant, associations were reported as follows: (1) HLA-A mismatch with lower acute GvHD risk [49] or higher chronic GvHD risk [44], (2) HLA-C mismatch with higher chronic GvHD risk [41], (3) HLA-DRB1 mismatch (over match) with improved survival [44,45], lowered relapse risk [41], no impact [39], or grade ≥2 acute GvHD risk (if antigenic mismatch) [43], and (4) DPB1 non-permissive (over permissive) with improved survival [41,44,45]. Here, HLA-DRB1 is linked to graft versus host disease.