HLA-DRB1 and nasopharyngeal carcinoma: To answer this question, we continued to analyze the association between the 30 bp deletion mutation rate and the high frequencies of class-I HLA alleles (HLA-A and HLA- B) and class-II HLA alleles (HLA-DRB1, HLA-DQB1, and HLA-DAB1) in patients with NPC.