Bidirectional HLA Mismatch

**Semantic type:** Classification

**Definition:** The state when a recipient of a hematopoietic stem cell transplantation is not fully matched with their unrelated adult volunteer donor for HLA-A, HLA-B, HLA-C, and HLA-DRB1 and both are heterozygous for different alleles at one locus.

**Synonyms:** - Bidirectional HLA Allele Mismatch - Bidirectional HLA Locus Mismatch