Interaction Between G954C Mutation In INOS Gene And Environmental Factors In Chronic Hepatitis B Disease

Background:Chronic hepatitis B disease,as a kind of infectious disease,can do great harm to human health and quality of life,it is also an important cause of death and burden of disease in China and many other countries.It is,at present,a severe public health problem.So to further the study on the pathogenesis of chronic hepatitis B is very important for the prevention and control of the disease.Chronic hepatitis B is a multi-factorial disease,which is related to both the genetic and environmental factors.Gene has an important role in chronic hepatitis B incidence.There are research papers that indicate gene-environment interaction makes great contribution to the risk of chronic hepatitis B.With the advance of Human Genome Project and application of molecular biologic technics,it has become more and more popular in medical fields to clarify the pathogenesis of chronic hepatitis B at gene level.Inducible nitric oxide synthase(iNOS),as a key enzyme catalysing the synthesis of nitric oxide(NO)in liver,has been much concerned recently. Homozygous mice for the knockout of the inducible nitric oxide synthase(iNOS) gene have a significant higher level of HBV than the control mice.And the level of iNOS in virus hepatitis is significantly higher than other liver ailments,so it indicates iNOS has relationship with HBV infection.Therefore,inducible nitric oxide synthase (iNOS)is an important molecule that is involved in the host defense against viral infections.Mutations in iNOS gene may affect the function and activity of iNOS,and accordingly it affects chronic hepatitis B disease incidence.In recent years,reports are extremely rare presently on the association between the G-954C mutation in iNOS gene and chronic hepatitis B in the Han nationality of China,and the interaction between the G-954C mutation and environmental factors.Objective:To explore the association between the G-954C mutation in iNOS gene and Chronic hepatitis B;and further to explore and assess the interaction effect between the G-954C mutation and environmental factors on chronic hepatitis B.Methods:A hospital-based case-control study was conducted.A total of 237 diagnosed chronic hepatitis B patients and 238 health adults were recruited as study subjects.Hepatic function and HBV-DNA contents in patients were determinated. Polymerase chain reaction with BsaI restriction enzyme digestion was performed to detect the G-954C mutation in iNOS gene.Univariate test and multiple logistic regression models were used to analyze the association between the G-954C mutation in iNOS gene and chronic hepatitis B.Interaction coefficients(γ,γ=β_eg/β_e)were calculated to determinate whether the G-954C mutation in iNOS gene and environmental factors show an interaction in chronic hepatitis B,and to assess the dose-effect relationship of the interaction.Results:1.iNOS gene G-954C mutation was significantly associated with chronic hepatitis B.There was no significant difference in G-954C mutant genotypes between chronic hepatitis B group(GG,GC and CC were 78.9%,19.0%and 2.1% respectively)and control group(GG,GC and CC were 86.6%,12.6%and 0.8% respectively)(p=0.074).However,mutant genotypes(GC+CC)in chronic hepatitis B group were significantly higher than those in control group(p=0.027).Mutant C allele frequency in chronic hepatitis B group was also significantly higher than that in control group(11.6%versus 7.1%,p=0.018,OR=1.721,95%CI:1.059-2.798). Multiple logistic regression analysis at 0.05 significant level with sex,age,smoking, alcohol drinking covariates indicated that the G-954C mutation still had significant effect on chronic hepatitis B group(p=0.047,OR=1.565,95%CI:1.005-2.438).2.There is significant difference in HBV-DNA quantity between(GC+CC) genotype and GG genotype in chronic hepatitis B group(p=0.014).3.There is no significant difference in ALT level between(GC+CC)genotype and GG genotype in chronic hepatitis B group(p=0.126).Multiple logistic regression analysis with sex,age,smoking,alcohol drinking covariates indicated that the G-954C mutation still had no significant effect on ALT level.4.There is no significant difference in AST level between(GC+CC)genotype and GG genotype in chronic hepatitis B group(p=0.205).Multiple logistic regression analysis with sex,age,smoking,alcohol drinking covariates indicated that the G-954C mutation still had no significant effect on AST level(p=0.331).5.iNOS gene G-954C mutation was significantly associated with state of chronic hepatitis B disease.There is significant difference in state of chronic hepatitis B group between(GC+CC)genotype and GG genotype in chronic hepatitis B group(p=0.026).6.There is no significant difference in complications between(GC+CC) genotype and GG genotype in chronic hepatitis B group(p=0.084).Multiple logistic regression analysis with sex,age,smoking,alcohol drinking covariates indicated that the G-954C mutation still had no significant effect on complications(p=0.136).7.The interaction existed in iNOS gene G-954C mutation and alcohol drinking (p=0.134,OR=1.679).Multiple logistic regression analysis with sex,age,smoking, covariates indicated that the interaction existed between iNOS gene G-954C mutation and alcohol drinking(p=0.178,OR=1.738).8.The interaction didn't exist in iNOS gene G-954C mutation and smoking (p=0.592,OR=1.232).Multiple logistic regression analysis with sex,age,alcohol drinking covariates indicated that the interaction didn't exist between iNOS gene G-954C mutation and smoking(p=0.827,OR=1.104).Conclusions:1.The G-954C mutation in iNOS gene might serve as a major risk factor to chronic hepatitis B in the Han nationality of China.2.There is no significant difference in ALT level,AST level,complications between(GC+CC)genotype and GG genotype in chronic hepatitis B group,iNOS gene G-954C mutation was significantly associated with HBV-DNA quantity and state of chronic hepatitis B disease.There is significant difference in state of chronic hepatitis B group between(GC+CC)genotype and GG genotype in chronic hepatitis B group(P=0.026).3.The interaction existed in iNOS gene G-954C mutation and alcohol drinking, but there wasn't interaction between iNOS gene G-954C mutation and smoking.