HLA-DQA2 and Parkinson disease: HLA-DRB5 (59, 60), HLA-DQA2 (60, 61) and HLA-DPB1 (62) have been reported to be associated with PD, which were all up-regulated in memory B cells of PD patients compared to healthy controls in this study, suggesting the enhanced capacity of antigen presentation in B cells of PD patients.