Association of variants in HLA-DP on chromosome 6 with chronic hepatitis B virus infection and related phenotypes.

Hepatitis B virus (HBV) infection affects more than 2 billion people throughout the world. Among them, more than 240 million have chronic infection. Every year, 0.5-1.2 million people die of chronic hepatitis B virus infection (CHBVI), and approximately 60% of liver cancers are related to CHBI and subsequent liver cirrhosis (LC). These HBVI-related diseases impose a considerable economic burden as well as morbidity on patients, families, and society. Family and twin studies have indicated that the host genetic constitution greatly influences the clinical outcomes of HBV infection. During the past several years, genome-wide association studies (GWAS) have identified susceptibility variants for various HBVI-related diseases. Of these variants, SNPs rs3077 and rs9277535 in HLA-DP on chromosome 6 show the strongest evidence for association with CHBVI and with viral clearance. However, whether there exists an association between HLA-DP variants and the progression of CHBVI remains to be determined. Thus, further study should focus not only on identifying more variants in HLA-DP that are associated with various HBVI-related diseases but also on characterizing any newly discovered functional variants at the molecular level. Further, given the complexity of CHBV infection and its progression, gene-gene and gene-environment interactions should also be taken into consideration. Moreover, because both smoking and alcohol affect HBV infection and progression, it is important to understand how these factors interact with genetics to influence HBV-related diseases.