Association Of The -759C/T Polymorphism Of The 5-HT_2C Receptor Gene With Type 2 Diabetes Mellitus In Dongxiang And Han Population Of Gansu Province

Objectives To investigate the association of the -759C/T polymorphism of the 5-HT_2C receptor gene(5-hydroxytryptamine 2C receptor,HTR2C) with type 2 diabetes(T2DM) and obesity in Dongxiang and Han population.Methods The -759C/T polymorphism of the 5-HT_2C receptor gene was detected by PCR-ligase detection reaction(PCR-LDR) technique in 100 type 2 diabetics and 126 normal control subjects of Dongxiang population,133 type 2 diabetics and 135 normal control subjects of Han population.At the same time,we measured the body height,body weight, waist circumference,hip circumference,systolic blood pressure(SBP),diastolic blood pressure(DBP).Total cholesterol(TC),triglyceride(TG),high density lipoprotein cholesterol(HDL-C),low density lipoprotein cholesterol(LDL-C) and fasting blood glucose levels were determined by automatic biochemistry analyzer.Fasting blood insulin concentration was measured using insulin radioimmunoassay kit.The homeostasis model assessment insulin resistance index(HOMA-IR) was calculated by the formula:fasting glucose(millimoles per liter)×fasting insulin(microunits per milliliter)/22.5.Results1.Clinical data comparison between the diabetic group and control group in Dongxiang population:In the diabetic group,the levels of waist circumference,waist-to-hip ratio, fasting blood glucose,fasting blood insulin,HOMA-IR,systolic blood pressure(SBP), diastolic blood pressure(DBP),triglyceride(TG),and low density lipoprotein cholesterol (LDL-C) were significantly higher than those in the control group(P＜0.05).2.Clinical data comparison between the diabetic group and control group in Han population: In the diabetic group,the levels of waist circumference,waist-to-hip ratio,fasting blood glucose,fasting insulin,HOMA-IR,SBP,and TG were significantly higher than those in the control group(P＜0.05).HDL-C was significantly lower than it in the control group (P＜0.05).3.In Dongxiang population,the frequency of CC,CT genotypes in female diabetics and normal control subjects were 80.6%,19.4%and 61%,39%,respectively.The frequency of CT genotype was significantly lower in the female diabetics than in the normal control subjects(x²=3.950,P=0.047),and the allele frequencies showed no statistical difference between two groups(x²=3.210,P=0.073).The frequency of C and T hemizygote also showed no statistical difference between male diabetics and normal control subjects(x²= 0.122,P=0.727).4.In Han population,the frequency of genotypes and alleles of -759C/T showed no statistical difference between diabetics and normal control subjects(P＞0.05).5.The frequency of C and T allele showed no statistical difference between Dongxiang and Han population in normal control subjects(x²=3.413,P=0.065).The frequency of C and T hemizygote showed no significantly difference between male Dongxiang and Han population(x²=0.367,P=0.545).The frequency of CT genotype in female Dongxiang and Han population were 39%and 21.9%,respectively.The distribution of CT genotype showed significantly difference between two populations(x²= 4.272,P=0.039).6.In Dongxiang population,the BMI,WC,WHR,FPG,Fins,BP,TC,TG,HDL-C,and LDL-C were no significantly difference between the C+CC genotype and T+CT genotype in control group and type 2 diabetic group respectively(P＞0.05).7.In Han population,the HOMA-IR was significantly higher in C+CC genotype than in T+CT+TT genotype(t=2.267,P=0.026).8.The frequency of genotypes and alleles of -759C/T showed no statistical difference between obesity and control subjects in Dongxiang and Han population.Conclusions Thc correlation between the -759C/T polymorphism of the HTR2C gene and type 2 diabetes may have ethnic difference.In Dongxiang population,the polymorphism was related to the occurrence of T2DM in female.-759C→T may be a protective factor for the development of T2DM.The polymorphism was not related to the occurrence of T2DM in Han population.HTR2C gene -759CC genotype and -759C hemizygote may be associated with the higher HOMA-IR in type 2 diabetic patients of Han population.The -759C/T polymorphism of the HTR2C gene was not associated with obesity in both Dongxiang and Han population.