In HCT from haploidentical family donors, 1 HLA haplotype is shared (blue) and the other is unshared (ie, patient-specific [red] or donor-specific [yellow]). DRB1 GvH mismatches are present in HLA-DRB1 heterozygous patients carrying a different HLA-DRB1 allele than the donor on their unshared haplotypes (ie, patient allele 1 and donor allele 2). B-leader matches are present when the HLA-B alleles on the unshared haplotypes of patient and donor carry an identical leader peptide sequence at position −21 (ie, methionine [M] or threonine [T]).⁴ DPB1 TCE nonpermissive mismatches are present when the HLA-DPB1 alleles on the unshared haplotypes of patient and donor belong to different TCE groups (ie, patient TCE 1 and donor TCE 2 or 3, patient TCE 2 and donor TCE 1 or 3, or patient TCE 3 and donor TCE 1 or 2), with the relevant TCE group in the patient also not present on the shared haplotype.⁵ Arrows indicate a significant association with better DFS and better overall survival or lower relapse after haplo-HCT in the presence of the specific HLA matching status compared with the reference, as per multivariable analyses presented in Fuchs et al.¹