HLA allele Non-HLA allele Donor-Recipient relation Clinical situation
identical identical syngenic Monozygotic twins
identical different allogenic Related or unrelated donors
different different allogenic Unrelated donors
Different identical allogenic artificial
Table 1: Comprehensive outlook of different clinical transplantation scenarios. Characteristics of allogeneic incompatibilities for various donor: recipient constellations in a HSCT situation. In a clinical transplantation setting where related/ unrelated donors are considered for transplantation, HLA alleles remain either identical/ different while the mHAGs are always different among the donor: recipient pair and its effects must be taken into account. The HLAdifferential and mHAG-identical situation does not occur, and therefore in a natural setting, it is not possible to determine the HLA mismatch effects exclusively. The lower line emphasizes the characteristics of the artificial allogeneic system, where the magnitude of HLA mismatch effects can be determined independent of mHAG effects.