Association Between Fas Gene Polymorphisms And Susceptibility To HBV-Related Liver Diseases

Objectives We detected single nucleotide polymorphisms (SNPs) in the promoter region of the Fas gene at position-1377G/A (rs2234767) and-670A/G (rs 1800682) in patients with HBV-related liver diseases and healthy subjects in Guangxi, to examine the association between such two polymorphisms of Fas gene and the risk of developing chronic hepatitis B (CHB), HBV-related liver cirrhosis (LC) and hepatocellular carcinoma (HCC), which might provide new genetic markers for the prevention and treatment of HBV-related liver diseases.Methods Two hundred and twenty-five healthy control subjects and 110 CHB patients,88 LC patients,258 HCC patients from Guangxi were included in our study. DNA was extracted from the peripheral blood leukocytes. We genotyped the polymorphisms of the Fas gene at position-1377G/A and-670A/G by using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method, and DNA sequencing method was also applied to validate the accuracy of genotype. Hardy-Weinberg equilibrium was tested to verify the crowd representativeness of study subjects. Chi-square test was used to examine the difference of genotype and allele frequencies among groups. Association of Fas gene polymorphism with risk of HBV-related liver diseases were estimated by calculating Odds ratio (OR) and 95% confidence interval (95%CI) using logstic regression analysis. SHEsis software online was applied for the haplotype analysis.Results1. Significant differences of age and gender composition were observed between CHB, LC, HCC group and control group (p<0.05). Significant differences of ethnicity composition between HCC group and control group, smoking status between LC group and control group, and drinking status between CHB group and control group were found. The differences of other baseline information between case group and control group were not statistically significant (p>0.05). The genotype frequencies of the two polymorphisms among controls and patients were in agreement with Hardy-Weinberg equilibrium (p>0.05).2. We tested GG, GA and AA genotypes in Fas-1377G/A, and AA, AG and GG genotypes in Fas-670A/G in each group. No significant difference was observed in the distribution of genotypes or allele frequencies of Fas-1377G/A and Fas-670A/G among the four groups (p>0.05). After adjusting for age, gender, smoking status, drinking status, ethnicity and BMI, logstic regression analysis showed no significant association between gene polymorphisms of Fas-1377G/A or Fas-670A/G and the risk of CHB, LC or HCC comparing with control group.3. When stratified by gender, Fas-670 AG genotype increased the risk of LC compared with AA genotype (OR 2.222,95%CI 1.033-4.781) in men. When stratified by age, Fas-1377GA genotype was significantly associated with increased the risk of HCC for those over age 50 (OR 2.761,95% CI 1.270-6.005), and Fas-670 AG genotype had a similar effect on the risk of HCC for those over age 50 (OR 2.863,95%CI 1.341-6.112). When stratified by ethnicity, Fas-1377 AA genotype and A allele significantly decreased the risk of LC in Zhuang ethnic population (OR 0.232,95%CI 0.060-0.891; OR 0.522,95%CI 0.286-0.953), and Fas-670 GG and G allele might be protective factors for LC in Zhuang ethnic population (OR 0.236,95%CI 0.061-0.922; OR 0.539,95% CI 0.296-0.984). However, stratification by smoking status, drinking status or BMI showed no association between gene polymorphisms of Fas-1377G/A or Fas-670A/G and the risk of CHB, LC or HCC.4. The haplotype analysis for Fas-1377G/A and Fas-670A/G showed no significant differences of AA, AG, GA, GG haplotypes between each case group and control group (p>0.05).Conclusions1. Fas-1377 GA genotype may be a risk factor of developing HCC for those over age 50, while Fas-1377 AA genotype and A allele may decrease the risk of LC in Zhuang ethnic population.2. Fas-670 AG genotype appears to contribute to risk of LC in men and risk of HCC for those over age 50. Fas-670 GG genotype and G allele may play a protective role in the risk of LC in Zhuang ethnic population.3. The haplotype analysis for Fas-1377G/A and Fas-670A/G showed no association with the risk of CHB, LC or HCC.