HLA-DRB1 and Autoimmunity: Donor 5443 was unusual, in that this donor was homozygous for a total of 7 out of 9 HLA alleles: HLA-B, HLA-C, HLA-DRB1, DRB4, DQA1, DQB1 and DPA1, with specific HLA alleles more predisposed to autoimmunity (Table 1).