A Molecular Epidemiology Study On The Association Of ADIPOQ Gene Polymorphisms With Metabolic Syndrome And Its Components

The metabolic syndrome (MetS), which has seriously impact to human health, isnow well-recognised as being associated with increased risk of cardiovascular disease,shows obesity, hypertension, hyperglycemia, elevated plasma triglycerides and lowhigh-density cholesterol. In2005, the International Diabetes Federation(IDF)estimated that there were about a quarter of people in the world with MetS. MetS isone of the important risk factors which can increase the mortality rates of diabetesand cardiovscular disease. With the development of economy and the change of thepeople’s lifestyle, the prevalence of MetS increases rapidly in nearly years. Therefore,the pathogenesis and preventive measure of MetS are concerned widely.MetS is an obvious heterogeneity disease with multiple environmental factorsand multiple genes, and its principal contradiction is excess calories lead to the fataccumulated unduly in adipose tissue or non-fatty tissues and correlative insulinresistance. Adipose tissue is not only a tissue which stores excess energy, but also anendocrine tissue regulating the metabolism. Adiponectin is a protein exclusivelysecreted by adipose tissue and also an adipocytokine which plays a pivotal role in theregulation of insulin action and the metabolism of glucose. Adiponectin is the geneproduct of ADIPOQ which has been mapped on chromosome3q27.Varioussingle-nucleotide polymorphisms (SNPs) of the human adiponectin gene (ADIPOQgene) were reported to be associated with MetS traits(obesity, T2DM, and insulinsensitivity) in many ethnic groups. At present, researchers found that MetS andhypoadiponectinemia are associated with ADIPOQ gene polymorphism and rarely missense-mutationIn this study, we conducted a case-control study of the Chinese southeast Hanpopulation,and analyzed the potential functional SNPs, tagging SNPs andhaplotype analysis, combined with environmental factors, to find whether ADIPOQgene polymorphisms and its phenotype(serum adiponectin level) are associated withthe MetS; We further researched the association between ADIPOQ genepolymorphisms and the components of MetS, to investigate the association ofADIPOQ gene and the susceptibility of MetS in southeast Han population of China.In order toprovide the scientific evidence for the prevention of MetS and screening of high-riskpopulation.Part Ⅰ SNPs in ADIPOQ gene and metabolic syndrome riskWe conducted a case-control study, and studied gene polymorphisms from twoaspects of potential functional SNPs and tagging SNPs. By utilizing TaqMan assaydetection technology. We detect all subjects(1049MetS patients,1092healthcontrols)and alyzed the association between the polymorphisms of ADIPOQ gene andMetS in the Chinese Han population. Associations between genotypes and MetS risk(ORs and95%CI) were estimated by logistic regression. Basing on MATLAB7.0software platform, BP artificial neural network prediction model was established andeach input neurons’ mean impact value (MIV) could be calculated. The main resultswere as follows:1. The distribution in cases and controls of SNPs of ADIPOQ geneWe analyzed ten SNPs of ADIPOQ gene. After adjustment for age, gender,smoking, drinking and physical activity, Compared with the wild-type homozygoters1063539GG, the variant genotypes GC and the combined genotype GC/CC ofrs1063539were all associated with a significant risk effect for MetS [AdjustedORs(95%CIs)=1.22(1.01-1.49),1.24(1.03-1.49)].The variant genotypes rs266729CG,16861205AA, rs7649121AT and the combined genotype AT/TT were all associatedwith a significantly decreased risk of MetS compared with the wild-typehomozygote.[Adjusted ORs (95%CIs)＝0.81(0.67-0.99),0.49(0.28-0.85),0.79 (0.64-0.96),0.80(0.66-0.97)]. After inspected by thousand times permutation test, thefrequency distribution of those sites genotype between the case group and controlgroup still existed statistical differences. No evidence suggested other SNPs wereassociated with MetS(P＞0.05).2. Stratified analysis by gender of SNPs of ADIPOQ geneThe stratified analysis by gender showed that significantly lower risk of MetSwas observed in females who carried the rs16861205AA genotype [Adjusted OR(95%CI)=0.34(0.15-0.80)]. Similarly, a decreasing risk of MetS was observed inmales, who carried rs7649121AT and rs7649121AT/TT genotype, compared with theAA genotype [Adjusted OR (95%CI)=0.68(0.51-0.91),0.71(0.55-0.95)].3. Comparison of serum levels of adiponecin in SNPs genotypes of ADIPOQ geneWe calculated the adiponectin levels in different genotypes of the four SNPs(rs266729, rs16861205, rs1063539and rs7649121) genes which had shown theassociation with MetS in the logistic regression analysis. In the case group, patientswith genotype CG(6.99±2.80mmol/L) and the combined genotypeCG/GG(6.96±2.75mmol/L) of rs266729had higher levels of serum adiponectin thanthose with the genotype CC(6.58±2.13mmol/L),(P=0.034,0.035).Patients withAT(7.03±2.74mmol/L) and the combined genotype AT/TT(6.98±2.72mmol/L) ofrs7649121also had higher levels of serum adiponectin than those with the AAgenotype(6.59±2.22mmol/L),(P=0.013,0.022). No evidence suggested other twoSNPs were associated with the adiponectin levels(P＞0.05).4. Haplotype analysisIn the haplotypes of eight tagging SNPs, compared with the most commonhaplotype CTGAGGTC, in cases,the haplotype GGAAAATC and GGGTAACC wereless common (10.7%and4.5%) than in the controls(12.1%and5.9%). The twohaplotypes were associated with a significant protective effect for MetS [AdjustedORs (95%CIs)=0.70(0.54-0.91),0.65(0.46-0.92)].In the haplotype analysis of the two potential functional SNPs, there were nohalotypes which may increase or decrease risk of MetS compared with the mostcommon haplotype, even after adjusting for age, gender, smoking, drinking and physical activity(P＞0.05).5. Application of BPANN on the impact of gene and environmental factors to thesusceptibility of MetSThe mean impact value (MIV) for each input variables were calculated and thesequence of the factors according to their absolute of MIVs were sorted. By BPANNanalysis, the top ten sequences according to the importance of the MetS relatedfactors was in the order of BMI, rs1063539,diabetes family history, rs182052, serumadiponectin level, rs2241767, physical activity, gender, hypertension family history,rs12495941. The top four SNPs(rs1063539, rs182052,rs2241767, rs12495941) wereanalyzed by haplotype analysis. Compared with the most common haplotype GAAG,halotype CGGT can increase risk of MetS after adjusting for age, gender, smoking,drinking and physical activity [OR (95%CI)=1.30(1.08,1.57)].Part Ⅱ the Association of ADIPOQ Gene Polymorphisms andthe components of Metabolic SyndromeIn this study, we based on the PartⅠof the Association of ADIPOQ genepolymorphisms and the susceptibility of MetS, and selected rs266729, rs16861205,rs1063539and rs7649121genes which had shown the association with MetS in thelogistic regression analysis. We further researched the association of ADIPOQ genepolymorphisms and the components of MetS in the case group (n=1049).On the viewof MetS molecular etiology, further to investigate the mechanism of theADIPOQ gene polymorphisms.The main results were as follows:1. Comparison of the levels of triglycerides(TG) in SNPs genotypes of ADIPOQ genePatients who carriers with genotype CG of rs266729had lower levels of TG(2.62±2.50mmol/L) than those with the genotype CC (2.96±2.71mmol/L),(P=0.039),after adjusting for age, gender, HDL-C, FPG, BP and WC, smoking,drinking,physical activity,2. Comparison of the levels of high density lipoprotein (HDL-C) in SNPs genotypesof ADIPOQ genePatients who carriers with genotype CG of rs266729had higher levels of HDL-C (1.20±0.49mmol/L)than those with the genotype CC (1.13±0.37mmol/L),(P=0.010),after adjusting for age, gender, TG, FPG, BP, WC, smoking, drinking andphysical activity.3. Comparison of the levels of fasting glucose(FPG) in SNPs genotypes of ADIPOQgenePatients who carriers with genotype AA of rs16861205had lower levels of FPG(8.28±3.22mmol/L) than those with the genotype GG(9.04±4.04mmol/L),(P=0.019),after adjusting for age, gender, TG,HDL-C,WC,smoking, drinking and physicalactivity.4. Comparison of the levels of blood pressure(BP) in SNPs genotypes of ADIPOQgenePatients who carriers with genotype CC of rs1063539had higher levels ofsystolic blood pressure(141.17±22.66mmHg) and diastolic bloodpressure(88.02±13.60mmHg) than those with the genotype GG(137.82±19.00mmHg),(85.03±11.36mmHg)(P=0.048,0.013).Patients with genotypeAA of rs16861205had lower levels of systolic blood pressure(128.68±15.51mmHg)and diastolic blood pressure (81.91±13.02mmHg) than those with the genotypeGG(138.08±20.26mmHg),(85.19±11.82mmHg),(P=0.028,0.029), after adjustingfor age, gender, TG, HDL-C, FPG, WC, smoking, drinking and physical activity,5. Comparison of the levels of waist circumference (WC) in SNPs genotypes ofADIPOQ geneFemale patients who carriers with genotype AAof rs16861205had lowerWC(85.89±4.65cm) than those with the genotype GG(87.23±8.74cm),(P=0.026),after adjusting for age, gender, TG, HDL-C, FPG, BP, smoking, drinking andphysical activity.