Study participants
We retrospectively reviewed the medical records of patients with HLA results from January 1, 2000, to June 31, 2019, using SUPREME®, a clinical data warehouse of the Seoul National University Hospital (SNUH). The tested HLA gene families included HLA-A, HLA-B, HLA-C, HLA-DR, and HLA-DQ. The study was approved by the Institutional Review Board (IRB) of Seoul National University Hospital (No. H-1811-157-989).