【作者】 陈欣；

【导师】 刘克强；

【作者基本信息】 天津医科大学 ， 心血管内科， 2002， 硕士

【摘要】 [目的]研究冠心病患者同型半胱氨酸、叶酸、维生素B₁₂水平及同型半胱氨酸代谢相关酶甲基四氢叶酸还原酶（MTHFR）基因C677T和胱硫醚-β-合成酶（CBS）基因T833C位点和G919A位点碱基突变与冠心病的关系。 [方法]用酶联免疫试剂盒测定血浆同型半胱氨酸水平，以放射免疫法测定维生素B₁₂和叶酸水平，盐酸胍法提取DNA，以多聚酶链反应-限制性内切酶片段长度多态性（PCR-RFLP）分析MTHFR基因中C677T基因型，采用扩增阻滞突变体系法检测CBS基因中T833C和G919A基因型。 [结果]冠心病组107例同型半胱氨酸水平为21.58±12.69gmol／L，对照组96例同型半胱氨酸水平为14.86±8.37gmol／L，冠心病组同型半胱氨酸水平显著高于对照组（p＜0.01）。冠心病组叶酸浓度平均2.78±1.66ng／ml，对照组叶酸浓度平均8.78±2.69ng／ml，冠心病组与对照组比较，血浆叶酸浓度明显降低（p＜0.01）；冠心病组维生素B₁₂浓度平均231.76±143.78pg／ml，对照组维生素B₁₂浓度平均508.71±347.37pg／ml，冠心病组与对照组比较，血浆维生素B₁₂浓度明显降低（p＜0.01）。MTHFR基因冠心病组为TT（+／+）型占28.1％，TC（+／-型占38.3％，CC型（-／-）33.6％；对照组为TT型占20.8％，TC型占41.7％，CC型占37.5％。冠心病组中TT型、杂合TC型及CC型频率分布与正常对照组无显著差异（x²=1.427，p＞0.05），T、C等位基因频率在冠心病组和对照组无显 同型半脱氨酸代谢异常与冠心病发病机制的研究 著差异（x 2一1．257，p＞0．05）。CBS基因 TS33C冠心病组 CC（十／＋）型 9例，CT（／－） 型26例，TT（－／－）型72例，对照组CC型2例，CT型9例，TT型85例。冠 心病组CC型、CT型、TT型频率分布及C、T等位基因频率分布均与正常对 照组有非常显著差异（分别为厂＝13．271，p＜0．005；x 2＝15．916，p＜0．005）。CBS 基因Ggl gA冠心病组AA（十／＋）型6例，AG（／一）型22例，GG一／一）型79例，对 照组AA型2例，AG型9例，GG型85例。冠心病组AA型、AG型、GG 型频率分布及AG等位基因频率分布均与正常对照组有非常显著差异（分别为 x＝7．098，p＜0．05；xZ＝8．218，p＜0．005）。MTHFR基因冠心病组中三种基因 型的HC Y水平有显著差异(F一．269，p＝0．026L 对照组中三种基因型的HCY 水平无显著差异J叫．235，p二0．623人两两比较中冠心病组的TT基因型者HCY 水平显著高于CC基因型…一．892，p—0刀13人 其它两两间HCY水平无显著 差异。CBS 中T833C基因冠心病组中三种基因型的HCY水平有显著差异 (F—3．984，P—0乃37厂 对照组中三种基因型的HCY 水平无显著差异 (F—l．173，P—0．563人 两两比较中冠心病组的 CC基因型者 HCY水平显著高于 TT基因型…一．714，p－0．047人CT基因型者HCY水平显著高于rT基因型 （q－3．986，p二0＊23），其它两两间 ＊＊Y水平无显著差异。＊＊S中＊919A基因 冠心病组AA、AG＊G三种基因型间HCY水平有显著差异(F－3．402，p－0刀41＼ 对照组中三种基因型的 HCY水平无显著差异(F叫刀32，p＝0．423人两两比较中 冠心病组 AA基因型 HCY水平显著高于 GG基因型(q－4刀 14，p－0刀25人 AG 基因型HCY水平显著高于GG基因型（q—3．895，p。0刀12入 其它两两间HCY 水平无显著差异。 l结论l 门）高同型半脓氨酸血症是冠心病发病的危险因素，血浆 HCY水 〕 同型半脱氨酸代谢异常与冠心病发病机制的研究平的升高与叶酸、维生素B；。的降低有关。（2）MTHFR基因C677T的TT突变、CBS T833C的 CC、CT突变、CBS GglgA的 AA、AG突变是高同型半耽氨酸血症的原因。（3）MTHFR基因 C677T多态性与冠心病的发生无显著相关，CBS基因T833C、GglgA多态性与冠心病的发生有关。更多还原

【Abstract】 Object To study the relationship among plasma homocystein（HCY）, folate, vitamine B₁2, C677T mutation of the methylenetetrahydrofolate reductase（MTHFR） gene, the T833C,G919A mutation of the cystathionine-β-synthase（CBS） gene and coronary heart disease.Methods Plasma homocystein（HCY） were determined by enzyme linked irnmunosorbent assay（ELISA）, plasma folate and vitamine B₁2 as cofactors of MTHFR and CBS were determined by radioimmunologic assay, genomic DNA abstract with methods of guanidine hydrochloric acid .The mutation of the 677C-T transition of MTHFR was investigated by using polymerase chain reaction-restriction fragment length polymorphism（PCR-RFLP）, the mutation of the 833T-C, 919G-A transition was identify with amplification refractory mutation system（ARMS） methods.Results The plasma HCY mean levels of 107 patients in CHD group were 21.58?2.69umol/L, in control group are 14.86 + 8.37umol/L. They are higher in CHD group than those in control group（p<0.01）. The mean level of folate and vitamineBn are lower in CHD group（2.78?1.66ng/ml, 231.76?143.78pg/ml） than those in control group（8.78?.69 ng/ml, 508.71 ?47.37 pg/ml）（p<0.01）. Thegenotype frequencies of MTHFR were 28.1% for TT, 38.3% for TC and 33.6% for CC in CHD group, respectively, while 20.8% for TT, 41.7% for TC and 37.5% for CC in control group. There was no significant difference in the frequencies of genotype and alleles between two groups（ x 2=1.427, p>0.05; x 2=1.257, p>0.05）. 9 C homogenotype of CBS gene T833C was found ,26 heterogenetic type was found and 72 T homogenotype was found in CHD group, and 2,9,85 in control group, respectively. There were obvious differences in frequencies of genotypes and alleles of the two groups （ x 2=13.271, p<0.005; x 2=15.916, p<0.005）. 6 A homogenotype of CBS gene G919A was found , 22 heterogenetic type was found and 79 G homogenotype was found in CHD group, and 2,9,85 in the control one, respectively. There were significant differences in frequencies of genotypes of the two groups （ x 2=7.098, p<0.05; x 2= 8.218, p<0.005）. There were obvious differences in HCY levels among the three genotype of MTHFR gene in CHD group（F=4.269,p=0.026）, but there was no difference in control group （F=1.235,p=0.623）. The plasma HCY levels in TT genotype of MTHFR gene were much higher than those in CC（q=3.892,p=0.013）, but no difference between the levels in TC and CC. There were obvious differences in HCY levels among the three genotype of CBS T833C gene in CHD group（F=3.984,p=0.037）, there was no difference in control group （F=1.173,p=0.563）. The plasma HCY levels hi CHD group of CC genotype were much higher than those in TT（q=3.714,p=0.047）. The plasma HCY levels in CHD group of CT genotype were much higher than those in TT（q=3.896,p=0.023）. There were obvious differences in HCY levels among thethree genotype of CBS G919A gene in CHD group（F=3.402,p=0.041）, there was no difference in control group （F=1.032,p=0.423）.Plasma HCY concentrations are higher markedly in patients with homozygosity（AA） and heterozygosity（AG） of the G919A mutation than those in patients without mutations（GG） （q=4.014,p=0.025; q=3.895,p=0.012）.Conclusions （l）Hyperhomocysteinemia is an independent risk factor of CHD. Hyperhomocysteinemia is related with folate and vitamineBu decreasing. （2）MTHFR and CBS are the main enzymes related to homocysteine metabolism. Their genetic mutations are possibly important mechanism of hyperhomocysteinemia.（3） MTHFR mutation is not related with coronary heart disease, CBS mutation is related with it.更多还原