Genetic Epidemiological Study On HBV Infection

BackgroundsHepatitis B virus (HBV) infection is one of important public health problems in China. Human being are susceptible to HBV universally with diversity and complex of clinical outcomes, which can not be explained by its virulence and environmental factors only and may be related to genetic susceptibility, especially the genes of antigen presenting system and virus clearance system. The tumor necrosis factor (TNF) gene is linked to the human leucocyte antigen (HLA) gene cluster closely, and may be involved in the expression and regulation of the immunomodulatory genes. It was reported abroad that TNF- α was involved in virus clearance and immune response to virus in the host and active vitamin D, as an important immunomodulatory hormone, could inhibit reponse of the Th1 and activate immune response of the Th2. Studies on association between the vitamin D receptor (VDR) gene polymorphisms and HBV infection have been seldomly reported so far.Objectives and methodsA population-based case-control study in nuclear families was conducted to analyze difference in prevalence of hepatitis B surface antigen (HBsAg) carrier status between the two types of families, those with (cases) and without (controls) HBsAg carrier(s), and associations of the TNF- α gene and VDR gene polymorphisms with HBsAg carrier status. Transmission/disequilibrium test (TDT) was used and haplotype- and genotype-based relative risk (HHRR and GHRR) was estimated to explore transmission/disequilibrium of the alleles of the TNF- α gene and VDR gene and the genotypes between parents and their affected offspring with a familial case-parent design. Traditional case-control study was used, as well, to analyze the genetic-environmental interaction on susceptinility to hepatitis B (HB), including alcohol drinking and cigarette smoking. It is expected that results of the studies will be theoretical importance in exploring genetic susceptibility to HB and helpful to predicting the outcomes of HBV infection.Results1. HBsAg carrier status appeared familial aggregation. Varied outcomes were observed in individuals of case and control families with similar exposure to HBV, and prevalence of HBsAg carriers status was higher in the members of case families than those of control ones, where most of infected individuals became self-limited.2. The genotypes frequencies of the TNF- α -863C/C and C/A, VDR-Taq I T/T and...