The Relationship Between Body Iron Status,TFR2 Gene Polymorphism And Non-alcoholic Fatty Liver Disease:A Case-control Study

[Objective]In vivo and in vitro experiments have demonstrated that iron overload associated with the risk of non-alcoholic fatty liver disease(NAFLD).However,some epidemiological studies yielded contradicting results.In the present study,we aim to analyze the effects of the dietary iron intake,body iron status and TFR2 gene polymorphism on NAFLD,which will provide Epidemiological evidence for the associations of iron overload with NAFLD.[Methods]1.We conducted a 1:1 case-control study including 280 NAFLD patients and280 age-and sex(±5)-frequency matched controls.A dietary survey was performed with a semi-quantitative food frequency questionnaire(SQFFQ).Then the dietary iron intake was calculated and the association between dietary iron intake and NAFLD was analyzed by the methods of Student's t-test and unconditional Logistic regression.2.We used ELISA to detect the plasma ferritin levels,sTFR2 levels and hepcidin levels,and calculated the ratios of sTFR2/SF,hepcidin/SF.The methods of MannWhitney Test and unconditional Logistics regression model were performed to evaluate the association between body iron status and NAFLD.3.Five SNPs in the TFR2 gene were selected and genotyped by the method of iMLDR in this case-control study.The Hardy-Weinberg equilibrium was checked in controls by using the chi-squared test.Unconditional univariate and multivariate logistic regression analyses were performed to obtain the crude and adjusted odds ratios(ORs)for risk of NAFLD,and their 95% confidence intervals(95%CIs).Haploview 4.2 software was used to construct the haplotypes.Haplo.stats software package developed by using the R language was used to estimate adjusted ORs and95% CIs for each haplotype.[Results]1.The mean of heme iron intake per day in patients with NAFLD [(5.20±2.27)mg/d] was higher than that in controls [(4.67±2.16)mg/d,P= 0.032].However,the means of total iron intake and non-heme iron intake were not significant difference between the two groups(P>0.05).After adjustment for the traditional risk factors of NAFLD,heme iron intake was associated with increased risk of NAFLD,the odds ratios(ORs)were 1.0(reference),1.73(0.98,1.99),and 2.13(1.25,3.62)for tri-sectional quantiles 1-3.Further adjustment for the total energy,the higher daily intake of heme iron still was a risk factor for NAFLD,but there are no associations between iron,non-heme iron and NAFLD.2.The results from the univariate Logistics regression model showed that,being compared with the first percentile of serum sTFR2(<10.04?g/L),the higher expressions of serum sTFR2(?19.11?g/L)had lower risk of NAFLD [OR=0.56(0.36,0.86)],so did the higher ratios of sTFR2/SF and hepcidin/SF.However,there were no statistical correlations between SF,hepcidin and NAFLD.The results from multivariate Logistics regression model showed that,adjustment for the traditional risk factors,being compared with the first percentile of SF(<123.91?g/L),the higher expressions of SF(?322.94?g/L)had higher risk of NAFLD [OR=0.56(0.36,0.86)].However,the higher ratios of sTFR2/SF,hepcidin/SF had lower risk of NAFLD.There were no statistical correlations between sTFR2,hepcidin and NAFLD.3.Compared with the AA genotype of the rs4434553,subjects with G allele had lower risk of NAFLD [ adjusted OR=0.45(0.25,0.81)].A allele of the rs2075 672 or rs1052897 had lower risk of NAFLD than the wild genotype GG or genotype TT abound female [OR=0.31(0.12,0.77)for A allele of the rs2075672,0.32(0.11,0.98)for the rs1052897].G allele of the rs4434553 or A allele of rs2075672 had lower risk of NAFLD than the wild genotype AA or genotype GG abound aged 60 yearsand above [OR=0.17(0.04,0.69)for G allele of the rs4434553,0.32(0.11,0.91)for A allele of the rs2075672].Calculating the GRS(genetic risk score)of each subject,we found the risk of NAFLD increased with the increase of the number of risk alleles(P for trend was 0.048).Being compared to the haplotype GT,which was the highest frequency in the study population,there were no statistical correlations between the haplotype AA,AT and NAFLD.[Conclusion]1.The higher heme iron intake maybe was a dangerous factor for NAFLD,so iron intake,especially the dietary heme iron intake,for the patients with NAFLD should be appropriate.2.The higher expression of SF might be a dangerous factor for NAFLD,but the higher ratios of sTFR2/SF,hepcidin/SF had the opposite effect.3.TFR2 gene polymorphism maybe associate with NAFLD,in which,the GA or GG genotype of the rs4434553,TA or AA genotype of the rs1052897,GA or AA genotype of the rs2075672 might be protective factors for NAFLD.