Flowchart for the selection of URD. A patient with malignant disease indication for URD HCT should be typed at high resolution (ie, the second field for the 6 HLA loci (-A, -B, -C, -DRB1, -DQB1, -DPB1) and a donor search initiated immediately. If only one 8/8 or 7/8 donor is available, this donor can be selected. In case of several 8/8 URD, the youngest donor should be selected,⁴  possibly with an HLA-DPB1 mismatch in the GVH direction permissive according to TCE3 and low risk according to the SNP proxy algorithms.¹¹  If no 8/8 or 7/8 donor is retrieved in the search, the probability of identifying such a donor should be assessed by the HapLogic probability score.²³  In case of high probability, the donor search should continue if the disease status of the patient does not impose extreme urgency, such as by requesting additional HLA typing on partially typed potential candidate donors. In case of low probability or extreme clinical urgency, alternative donors should be considered. For patients with nonmalignant disease, permissive HLA-DPB1 TCE3 mismatches hold no graft-versus-leukemia advantage, and the best 8/8 donor is the youngest with allele level HLA-DPB1 matching (12/12; see text).