HLA-DRB1 and hepatocellular carcinoma: A total of 13 HLA-DRB1 alleles were studied in the 8 case-control studies, but only 3 alleles (DRB1*07, DRB1*12, DRB1*15) was extracted from the studies to investigate their association with HCC, which were reported at least six of the eight case-control studies.