Several factors influence the
clinical course of hepatitis B virus (HBV) and hepatitis C virus (HCV)
infection. The
human leukocyte antigen (HLA) system, the major histocompatibility complex (MHC) in humans, has been considered one of the most important host factors with respect to outcomes. To date, conventional genotyping studies have shown that HLA class II loci are mainly associated with spontaneous clearance of HBV and HCV. However, the specific HLA locus associated with the outcomes of hepatitis virus
infection remains unclear. A recent genome-wide association study (GWAS) using a comprehensive approach for human genotyping demonstrated single nucleotide polymorphisms (SNPs) associated with the outcomes of hepatitis virus
infection. Examination of large numbers of cohorts revealed that several SNPs in both
HLA-DPA1 and
HLA-DPB1 loci are associated with persistent HBV
infection in Asian populations. To date, however, few studies have focused on
HLA-DP because polymorphisms of
HLA-DP haplotype do not vary greatly as compared with other loci of HLA. There are not enough studies to reveal the function of
HLA-DP. GWAS additionally detected candidate SNPs within HLA loci associated with chronic HBV or HCV
hepatitis, hepatic
fibrosis, and the development of
hepatocellular carcinoma. The results of one cohort were not always consistent with those of other cohorts. To solve several controversial issues, it is necessary to validate reported SNPs on HLA loci in global populations and to elucidate the HLA-allele-regulated molecular response to hepatitis virus
infection.