As the PDCD1 genotype of the donor has been previously described as having an impact on clinical outcome after HLA-identical sibling donor transplant, we explored the additive effect of the LAG3 rs870849 C>T and the PDCD1 rs36084323 A>G genotypes of the donor on the severe acute GVHD incidence. The gene discussed is PDCD1; the disease is graft versus host disease.