The Study On CBS Gene Polymorphisms, Plasma Homocysteine And Its Metabolic Related Factors In Isolated Systolic Hypertension

Objective To study the relationship between hypertension especially isolated systolic hypertension(ISH) and cystathionine β synthase(CBS) different site polymorphisms,variation of plasma homocysteine level, its partial metabolic related factors:folic acid,vitamin B and lipids;to screen the predisposing gene and intermediate phenotype of ISH.Methods 55 cases of ISH,50 of hypertension and 46 normal are enrolled to the study. Amplification retardation mutation system(ARMS) is used to analyze the gene polymorphisms of CBS.The plasma homocysteine levels are measured by high performance liquid chromatography method, and the concentration of serum lipids are measured by enzemy and Friedewald formula,the concentration of folic acid and vitamine are detected by radioimmunoassay.Results 1. There are three kinds of genotype in CBS polymorphism: wild type(-/-),heterozygous mutation(-/+)and homozygous mutation(+/+). 2. The genotype frequency of ISH group is as follow:29.1%,54.5% and 16.4%, which is significantly different from other two groups. 3.The mutation allele gene frequency of ISH is 15.2%, wild allele gene frequency is84.8%,whichboth different from non-ISH (=9.19, PO.01 ),but in hypertension group ,we can not found this result. 4.The alteration of plasma homocysteine level in three groups seem have the same tendency: the level of homozygous is higher than other two groups, but the level of homocysteine has nothing to do with the level of blood pressure. S.The homocysteine level of ISH( 17.7+8.5 umol/L) are higher ,but the concentration of folic acid( 19.98+13.1 nmol/L and 0.85+12 nmol/L) and vitamin B12(232.31+116 pmol/L and 271.76+141 pmol/L) become lower, which are all significantly different from control group (P<0.05) ,and we can not find the same results in hypertension group. (P>0.05) 6.Systolic blood pressure level has close correlated with folic acid concentration, but we do not find negative correlation between systolic blood pressure and vitamine 85. 7.We also find that plasma homocysteine level have correlation with TC and LDL concentration. 8.CBS genotype may contribute to the variation of systolic blood pressure level.Conclusion l.CBS gene polymorphism may be a risk factor and important genetic element for ISH by elevating homocysteine level . 2.The porportion of hyperhomocysteinemia ISH is 15.2%,then hyperhomocysteinemia may be the intermediate phenotype of ISH. 3.Homocysteine level is correlated with lipid concentration ,so they may have synergistic action in the pathogenesis of ISH. 4.There are negative correlation between homocysteinemia level and folic acidand vitamineB respectively, so we think the lower concentration of vitamine B and folic acid may be important nutritional factors for the hyperhomocystenemia in ISH patients.