In case of HLA miss-match transplantations, they can serve as a foreign antigen provoking immune reactions causing graft-failure or GVHD.5 Therefore, matched HLA antigens at A, B, C, DRB1, and DQB1 locus between recipient and donor as well as prescribing immunosuppressive regimens have been considered to limit GVHD occurrence.6 In spite of this strategy, GVHD occurs in approximately 30% of the patients who undergo allo-HSCT from HLA-matched related donors. This evidence concerns the gene HLA-DRB1 and graft versus host disease.