HLA-DRB5 and B-cell chronic lymphocytic leukemia: Another advantage is that it allows the analysis of some less investigated HLA class II genes, such as HLA-DPA1, HLA-DQA1, HLA-DRB3, HLA-DRB4, and HLA-DRB5, which allowed us to establish new associations between CLL and the genes in this class that were predisposing or protective.