Correlation Of ZAG Gene Polymorphism With Overweight Obesity

1. Background and ObjectiveNowadays the global incidence of obesity is increasing yearly with the social-economic development. Obesity that has been a common disease to threaten human health is the main risk factor of type2diabetes mellitus, hypertension, hyperlipidemia, coronary heart disease and other diseases. Obesity is a multifactorial disease, in which genetic factors play an important role in pathogenicity. ZAG has been found to be a new kind of lipid mobilizing factor recently. It has been confirmed both in experiments in vitro and animal experiments that ZAG can promote lipolysis and help to loss weight. However there were no large human sample reports on the relationship between single nucleotide polymorphism and obesity currently. Therefore the main objective of present study is to investigate the ZAG genetic polymorphisms association with obesity in China Beijing Han Race.2. Methods2.1Collection of clinical samples and dataA case-control design was applied, and two groups including obesity/overweight group and healthy control group were established. Collection of clinical data and biochemical Indexes including general information, past medical history, familial disease history, anthropometric indexes and biochemical indexes. According to admitting and excluding standards stated in the following, a total of573overweight or obese and304healthy persons were recruited in our study.Overweight/obesity GroupAdmitting Standard:Examination:BMI≥25.0kg/m2Biochemical indexes:FBG<5.6mmol/L, ALT<100U/L, AST<92U/L, Cr<132umol/L, BUN<7.14mmol/L.Excluding Standards:Liver disease and malignant tumor history;Anyone that not to comply with admitting standard. Healthy Control GroupAdmitting standard:Examination:BMI<25.0kg/m2, BP<140/90mmHgBiochemical indexes:FBG<5.6mmol/L, ALT<100U/L, AST<92U/L, Cr<132umol/L, BUN<7.14mmol/L, TC<5.69mmol/L, TG<1.69mmol/L, LDL-C<362mmol/L、HDL-C>0.92mmol/L.Excluding Standards:Liver disease and malignant tumor history;Anyone that not to comply with admitting standard.2.2Selection of SNPSelection Criterias of SNPs was based on3aspects following:①select the ZAG genetic tag SNP of China Bejing Han provided by Hapmap.②30DNA samples were amplified and sequenced the4exons of1.5kb upstream of start codon and0.9kb downstream of stop codon of ZAG gene to search SNPs.③The positive SNP site from abroad study. Five SNPs were found:rs2247607(A>T), rs4727442(G>T), rs4215(A>G),rs2527923(C>T) and rs2527882(C>T)2.3SNP genotyping1) The sequence including rs2247607with adenine can be identified and cut by restriction endonuclease. When adenine is replaced by thymine, it will loss the restriction site, therefore restriction enzyme digestion of restriction endonuclease is applied to determine the genotype of SNP.2) SNP genotypings of rs4727442, rs4215, rs2527923and rs2527882are operated by TaqMan probe technology.3. Results3.1Result of testing of sample mean to age, body weight, BMI, waist circumference, body fat, blood pressure, FBG, UA, TC, TG, HDL-C, LDL-C between overweight/obesity group and healthy control group shows that P<0.01. The difference is significant. 3.2Hardy-Weinberg equilibrium was calculated using the chi-squard test. All SNPs were in Hardy-Weinberg equilibrium either in the cases or control.3.3Compared overweight/obesity group with healthy control group, the P vaules of allele frequencies of each SNP such as rs2247607, rs4727442, rs4215, rs2527923and rs2527882, was0.303、0.906、0.763、0.795、0.778respectively. All P vaules were over0.05, which had no statistical significance, and suggested that all above SNPs have no obvious correlation with obesity.3.4Compared overweight/obesity group with healthy control group, the P vaules of genotype frequencies of each SNP such as rs2247607, rs4727442, rs4215, rs2527923and rs2527882, was0.582、0.217、0.369、0.938、0.942respectively. All over0.05, which had no statistical significance, and suggested that all above SNPs have no obvious correlation with obesity.3.5In dominance and recessive models, there was no obvious difference of the genotype frequency of all above SNPs between the overweight/obesity group and healthy control group, which indicated that all above genotype of SNPs had no obvious correlation with obesity.3.6Data analysis results calculated by Haploview4.1software show that rs2527882and rs2527923are in the same LD blok, meanwhile rs4215, rs4727442and rs2247607are in another LD blok, so two groups of haplotype can be constructed. The P vaules of all above haplotypes frequency between overweight/obesity group and healthy control group are all over0.05, which has no statistical significance.3.7Clinic data analysis showed that the difference of systolic blood pressures between the genotypes of rs4215, rs2527923and rs2527882is significant (P<0.05). The differences of body weights between rs4215’s genotype of GG and AG+AA, and between rs4727442’s genotype of GG and GT+TT were significant, which suggested that body weight may be related to rs4215and rs4727442. 4. Conclution4.1Five SNPs of ZAG gene (rs2247607, rs4727442, rs4215, rs2527923, rs2527882) had no association in Beijing Han population with obesity using case-control study.4.2The three SNPs of ZAG gene (rs4215, rs2527923, rs2527882) may have some association with SBP. The SNPs of ZAG gene (rs4215, rs4727442) may have some association with weight. The GG genotype of rs4215and rs4727442may increase risk of overweight.