A candidate is considered a 0-ABDR mismatch with a deceased or living donor if all of the following
conditions are met:
1. At least one donor antigen is identified for each of the A, B, and DR loci
2. At least one candidate antigen is identified for each of the A, B, and DR loci
3. The donor has zero non-equivalent A, B, or DR antigens with the candidate’s antigens
4. The donor and the candidate have compatible or permissible blood types
In cases where a candidate or donor has only one antigen identified at an HLA locus (A, B, or DR), the antigens are considered to be identical at that locus. A 0-ABDR mismatch may also be referred to as a zero mismatch or zero-antigen mismatch.
(OPTN Policy Definitions May 2021)
Glossary Term