More detail­ed typ­ing of the tis­sue cha­rac­te­ris­tics of a regis­tered donor, once the cha­rac­te­ris­tics alrea­dy deter­mi­ned (HLA‑A, HLA‑B, HLA‑C) have been found to match with tho­se of the pati­ent. The term is deri­ved from HLA-DR, which is exami­ned during this typ­ing procedure.