缺血性心、脑血管疾病患者同型半胱氨酸代谢相关酶基因突变频度的研究

目的 确定胱硫醚β－合成酶（CBS）基因844ins68、甲硫氨酸合成酶（MS）基因A2756G、亚甲基四氢叶酸还原酶（MTHFR）基因C677T三种同型半胱氨酸代谢相关酶基因突变在缺血性心、脑血管疾病发病中的意义。方法 PCR扩增102例脑梗死（BI）、73例心肌梗死（MI）患者及100名正常人的CBS、MS、MTHFR、MTHFR基因突变点,直接或经限制性内切酶消化后行聚丙烯酰胺凝胶电泳确定其原因型。结果 CBS844ins68和MSA2756G的基因突变率较国外所报道者低;CBS844ins68、MSA2756G和MTHFRC677T的各种基因型频率在患者组与正常对照组之间的差异无显著性;正常对照组CBS844ins68杂合突变率较患者组有升高趋势。结论 CBS844ins68、MSA2756G两种基因突变存在一定的人种或地域差异;CBS844ins68、MSA2756G和MTHFRC677T突变可能不足以构成长沙地区汉族人缺血性心、脑血管疾病的独立遗传性危险因子。     

亚甲基四氢叶酸还原酶基因多态性与深静脉血栓形成

目的　研究血浆同型半胱氨酸 (Hcy)水平及亚甲基四氢叶酸还原酶 (MTHFR)基因多态性与深静脉血栓形成 (DVT)的关系。方法　采用聚合酶链反应 限制性片段长度多态性法检测 10 1名健康对照者和 6 9名DVT患者的MTHFRC6 6 7T基因型 ,采用荧光偏振免疫法 (FPIA)测定血浆Hcy水平。结果　DVT组MTHFRC6 77T的TT基因型频率 (2 0 3% )高于对照组 (11 9% ) ,但两者差异无显著意义 (P >0 0 5 ) ,TT基因型不增加DVT患病的危险性 [比数比 (OR) =0 5 3,95 %可信限 (CI) 0 2 2 8～1 2 2 8]。DVT组的血浆Hcy水平为 (12 2± 8 7) μmol/L明显高于对照组的 (10 4± 4 8) μmol/L(P <0 0 5 ) ,轻度升高的同型半胱氨酸水平增加了DVT患病的危险性 (OR =2 5 3,95 %CI 1 0 4 9～ 6 0 5 )。两组人群MTHFRC6 77T的TT型血浆Hcy水平分别为 (19 7± 15 3) μmol/L和 (17 2± 7 8) μmol/L均明显高于同组CC型和CT型的血浆Hcy水平 (P <0 0 5 )。结论　轻度升高的同型半胱氨酸水平是我国北方地区汉族人DVT发病的独立危险因子 ,MTHFR基因C6 6 7T多态性可能与DVT无关联     

广西汉族老年缺血性脑梗死患者胱硫醚β-合酶(CBS)基因C770T突变频率观察

目的 初步探索胱硫醚β-合酶(CBS)基因C770T突变在广西汉族老年缺血性脑梗死发病中的作用.方法 用扩增阻滞突变体系法检测61例广西汉族老年缺血性脑梗死患者(病例组)及30例正常老年人(对照组)CBSC770T基因型;采用酶联免疫分析法检测血浆Hcy.结果 CBS C770T产生C/C和C/T两种基因型,病例组C/C及C/T型频率分别为45.90％及54.10％,C,T等位基因频率分别为72.95％及27.05％;对照组上述基因型及等位基因频率分别为60％,40％,80％和20％.卡方检验结果显示,两组之间基因型频率以及等位基因频率差异均无统计学显著性意义(x2分别为1.60,1.07,P均＞0.05);病例组血浆Hcy浓度为(21.82±3.92)μmol/L,其中C/C型为(19.29±4.19) μmol/L,C/T型为(24.36±4.25)μmol/L,对照组血浆Hcy为(13.15±2.11)μmol/L,其中C/C型和C/T型分别为(12.71±2.31)μmol/L和(13.59±1.91)μmol/L,经配对t检验,血浆Hcy在两组之间以及各基因型之间差异均有统计学显著性意义(t值分别为4.79,3.45和4.60,均P＜0.05).结论 CBS C770T基因突变对广西汉族老年缺血性脑梗死发病的作用可能非常有限,该基因位点突变可能不足以构成广西汉族老年缺血性脑梗死发病的独立遗传风险因素.     

同型半胱氨酸及其酶基因多态性与脑血栓形成的关系

目的探讨血浆同型半胱氨酸(Hcy)及其代谢酶N5,10亚甲基四氢叶酸还原酶(MTHFR)和胱硫醚β合成酶(CBS)基因多态性与脑血栓形成的关系。方法对87例脑血栓形成患者和80例对照者,应用高效液相色谱荧光法测定血浆Hcy浓度,应用聚合酶链限制性内切酶片段长度多态性分析和扩增阻滞突变体系法检测MTHFR及CBS基因型。结果病例组血浆Hcy浓度为(15.28±4.33)μmol/L,显著高于对照组的(11.32±3.86)μmol/L(P<0.001);不同基因型对血浆Hcy浓度影响不一致;两组间基因型分布、纯合子频率和等位基因频率无显著性差异(P>0.05)。结论血浆Hcy浓度升高是脑血栓形成的独立危险因素,单纯的MTHFR和CBS突变不能被确定为脑血栓形成的独立遗传危险因素。     

亚甲基四氢叶酸还原酶基因多态性及血浆同型半胱氨酸水平与脑血管病的关系

目的探讨亚甲基四氢叶酸还原酶(MTHFR)基因多态性及同型半胱氨酸(Hcy)水平与脑血管病的关系.方法应用聚合酶链反应-限制性片断长度多态性(PCR-RFLP)技术分析223例脑血管病患者及100名正常对照者的MTHFR基因多态性,同时应用高效液相色谱法(HPLC)测定其血浆Hcy水平.结果 MTHFR基因677位T等位基因携带频率脑血管病组(48.9%)显著高于正常对照组(30.5%,P<0.05),在脑出血患者组(53.3%)与脑梗死患者组(47.2%)之间差异无显著性(P>0.05);脑血管病组血浆Hcy水平[(20.01±8.89) μmol/L]显著高于对照组[(9.12±3.19) μmol/L,P<0.05],而脑出血患者组[(21.71±7.72) μmol/L]与脑梗死患者组[(19.35±8.51) μmol/L]间差异无显著性(P>0.05);各组中MTHFR TT型、TC型血浆Hcy浓度明显高于CC型.结论 MTHFR C677T突变可引起血浆Hcy水平升高,从而增加患脑血管病的危险度.     

血浆同型半胱氨酸及亚甲基四氢叶酸还原酶基因多态性与缺血性脑卒中的相关性研究

目的探讨血浆同型半胱氨酸(Hcy)及亚甲基四氢叶酸还原酶(MTHFR)基因多态性与缺血性脑卒中的相关性。方法急性缺血性脑卒中患者148例为缺血性脑卒中组,同时健康体检者100例为对照组。患者入院后行血压、血糖、血脂等常规检查。清晨空腹取肘静脉血5 mL,EDTA抗凝后离心10 min,分离上层血浆,检测Hcy水平;中层白细胞4℃保存,3 d内行基因组DNA提取。结果缺血性脑卒中组患者血浆Hcy水平为(15.9±1.9)μmol/L,对照组血浆Hcy水平为(12.0±1.1)μmol/L,2组比较有显著差异。缺血性脑卒中组的高Hcy血症患者比率为39.3%,明显高于对照组中高Hcy血症患者比率(19.0%)。2组T/T纯合子组的血浆Hcy水平均明显高于非T/T纯合子组。结论缺血性脑卒中与高Hcy血症相关,MTH-FR基因对血浆Hcy水平影响显著。     

同型半胱氨酸及胱硫醚β-合成酶基因多态性与2型糖尿病合并冠心病的关系

目的探讨我国北方汉族糖尿病(DM)合并冠心病(CHD)者同型半胱氨酸水平(Hcy)及Hcy代谢相关酶胱硫醚β-合成酶(CBS)的844ins68的基因多态性特点。方法检测104例2型DM合并CHD患者(DM合并CHD)、127例2型DM患者、61例CHD患者和91名健康对照者的Hcy、叶酸、维生素B12、总胆固醇(TC)、三酰甘油(TG)、高密度脂蛋白胆固醇(HDL-C)、低密度脂蛋白胆固醇(LDL-C)、载脂蛋白A-I(apo A-I)、载脂蛋白B(apo B)浓度。应用聚合酶链反应(PCR)分析CBS 844ins68基因多态性。结果DM合并CHD组Hcy水平明显高于DM组和对照组,叶酸、维生素B12水平明显低于DM组及对照组(P<0.01)。DM合并CHD组与CHD组Hcy、叶酸、维生素B12水平差异无统计学意义(P>0.05)。DM组与对照组之间Hcy、叶酸、维生素B12水平差异无统计学意义(P>0.05)。4组CBS 844ins68的基因型及等位基因频率差异均无统计学意义(P>0.05)。Lo-gistic回归分析显示高Hcy水平、年龄、TC是CHD发生的独立危险因素,OR值[95%可信区间(CI...     

血清肌钙蛋白T及血浆同型半胱氨酸在急性冠脉综合征中的作用

目的　探讨急性冠脉综合征时高同型半胱氨酸血症和心脏肌钙蛋白T的关系 ,评价高同型半胱氨酸血症是否能导致心肌损伤程度加重。方法　AMI 5 3例 ,UAP 5 5例 ,采用荧光标记免疫检测法测定血浆同型半胱氨酸 (Hcy) ,酶联免疫法 (ELISA)测定肌钙蛋白T(cTnT)。结果　AMI组Hcy明显升高时cTnT也明显升高 ,Hcy大于 16 0 μmol/L时cTnT明显高于Hcy小于 7 7μmol/L(P <0 0 1) ,Hcy分别为 7 7、9 0、11 3、14 3、16 0 μmol/L时cTnT分别为 4 6 3、4 6、4 8、6 2、7 8μg/L ;UAP组同样 ,Hcy分别为 9 8、11 0、12 1、12 8、15 4 μmol/L时cTnT分别为 0 0 3、0 0 3、0 0 2、0 0 4、0 15 μg/L ,最高浓度组与最低浓度组方差分析显示P <0 0 1。UAP组cTnT阳性者血浆Hcy浓度比阴性者显著升高 (P <0 0 0 1)。结论　血浆同型半胱氨酸浓度升高与ACS时心肌损伤有关。     

血浆总同型半胱氨酸水平与2型糖尿病和糖尿病肾病

目的探讨2型糖尿病(T2DM)和糖尿病肾病(DN)患者血浆总同型半胱氨酸(tHcy)水平、影响因素及与DN之间的关系。方法对诊断T2DM有大量蛋白尿的34例患者(组1),T2DM有微量白蛋白尿的60例患者(组2),T2DM微量白蛋白尿正常的148例患者(组3),尿微量白蛋白正常的非糖尿病对照的140例者(组4)的血浆tHcy及临床基本资料、血、尿相关指标进行调查和检测,并计算内生肌酐清除率(Ccr)和胰岛素抵抗指数(HOMA)。结果各组之间的血浆tHcy水平有显著性差异(P<0.001),组1 tHcy(16.9±5.0μmol/L),组2(13.4±3.7μmol/L),组3(11.8±4.2μmol/L)皆明显高于组4(11.0±6.0μmol/L)。组3、组2、组1的高同型半胱氨酸血症(HHe)发生率依次增高(15.5%,36.4%,58.8%),各组之间呈显著性差异(P<0.001),皆明显高于组4(7.9%)。组4至组1患者血清叶酸、VitB12呈明显下降趋势(P<0.001)。以糖尿病患者组(组1、组2、组3,n=242)lg tHcy为因变量,多元线性回归分析显示年龄、Scr、叶酸、VitB12是血浆lg tHcy的独立影响因素(R=0.613,R2=0.376)。在2型糖尿病患者(组1、组2、组3,n=242)中,以DN为因变量,经二项分类Logistic回归分析显示,血浆tHcy每升高5μmol/L,DN发病的危险率增加2.041倍(OR=2.041,95%CI 1.377~3.024)。结论尿微量白蛋白正常的T2DM患者血浆tHcy水平及HHe发生率明显升高,随DN的发展,血浆tHcy水平及HHe发生率呈梯度升高,各组之间有显著性差异。通过Logistic回归分析显示血浆tHcy水平升高是T2DM肾病的危险因素。提示临床需要关注和干预T2DM患者的高同型半胱氨酸血症。     

B族维生素降低脑卒中患者血浆同型半胱氨酸

目的:探讨B族维生素(叶酸、B6和B12)治疗对降低脑卒中病人血浆总同型半胱氨酸(tHcy)的效果。方法:收集脑卒中患者120例为病例组,选择120例性别、年龄和种族等与病例组具有可比性的无脑卒中者作为对照组,采用以荧光偏振免疫检测技术为基础的自动化免疫检测方法测定血浆tHcy。然后脑卒中组病人被随机给予安慰剂或维生素。采集空腹血,并在1年内检测血浆tHcy水平。结果:脑卒中组血浆tHcy水平(17．82±4．21)μmol／L,显著高于对照组(13．82±3．59)μmol／L(P<0．05)。治疗前脑卒中患者两组中tHcy平均水平相似(安慰剂组17．54μmol／L;维生素组17．96μmol／L; P>0．05);治疗后1年内,安慰剂组tHcy平均水平是18．63μmol／L,维生素组12．38μmol／L(差值6．25μmol／L,P<0．001)。结论:血浆tHcy水平升高与脑卒中的发生密切相关,维生素治疗能降低脑卒中患者的平均tHcy水平。     

High-level multiplex genotyping of polymorphisms involved in folate or homocysteine metabolism by matrix-assisted laser desorption/ionization mass spectrometry

BACKGROUND: Increased plasma total homocysteine (tHcy), a risk factor for cardiovascular disease, is related to genetic, environmental, and nutritional factors, in particular folate status. Future large epidemiologic studies of the genetic basis of hyperhomocysteinemia will require high-throughput assays for polymorphisms of genes related to folate and Hcy metabolism. METHOD: We developed a high-level multiplex genotyping method based on matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) for the detection of 12 polymorphisms in 8 genes involved in folate or Hcy metabolism. The assay includes methylenetetrahydrofolate reductase (MTHFR) 677C>T and 1298A>C, methionine synthase (MTR) 2756A>G, methionine synthase reductase (MTRR) 66A>G, cystathionine beta-synthase (CBS) 844ins68 and 699C>T, transcobalamin II (TCII) 776C>G and 67A>G, reduced folate carrier-1 (RFC1) 80G>A, paraoxonase-1 (PON1) 575A>G and 163T>A, and betaine homocysteine methyltransferase (BHMT) 742G>A. RESULTS: The failure rate of the assay was < or = 1.7% and was attributable to unsuccessful DNA purification, nanoliter dispensing, and spectrum calibration. Most errors were related to identification of heterozygotes as homozygotes. The mean error rate was 0.26%, and error rates differed for the various single-nucleotide polymorphisms. Identification of CBS 844ins68 was carried out by a semiquantitative approach. The throughput of the MALDI-TOF MS assay was 1152 genotypes within 20 min. CONCLUSIONS: This high-level multiplex method is able to genotype 12 polymorphisms involved in folate or Hcy metabolism. The method is rapid and reproducible and could facilitate large-scale studies of the genetic basis of hyperhomocysteinemia and associated pathologies.     

Accurate and rapid "multiplex heteroduplexing" method for genotyping key enzymes involved in folate/homocysteine metabolism

BACKGROUND: Hyperhomocysteinemia, which is often associated with low folate status, is an independent risk factor for cardiovascular diseases and several other pathologies. The four most common functional polymorphisms in genes involved in folate/homocysteine metabolism are methylenetetrahydrofolate reductase (MTHFR) C677T and A1298C, methionine synthase (MS) A2756G, and cystathionine beta-synthase (CBS) 844ins68. The pathogenic impact of these variants is under active investigation in many laboratories. However, conventional genotyping methods, mostly using PCR followed by restriction enzyme digestion, often are compromised by partial fragment digestion. There is, therefore, a need to develop more reliable approaches to genotyping the above polymorphisms that may be applied in large-scale studies. METHODS: Sequence-specific heteroduplex generators for each of the MTHFR and MS single nucleotide polymorphisms were generated by site-directed mutagenesis. These were subcloned into a single construct, pHcyHG-1, which could be multiplexed with a simple PCR amplification across the CBS 844ins68 polymorphic site to generate composite genotype-specific banding patterns from individual genomic DNA samples that could be electrophoretically resolved. RESULTS: The "multiplex heteroduplexing" method yielded unambiguous MTHFR, MS, and CBS genotypes in a single-tube reaction that could be analyzed in a single gel run. CONCLUSIONS: This method permits unambiguous genotyping of the four most common functional variants of enzymes involved in folate/homocysteine metabolism. It is rapid, reproducible, and inexpensive, and requires no special preparative or analytic facilities; consequently, it will facilitate large-scale studies of the genetic basis of hyperhomocysteinemia and the many pathologies that have been associated with this phenotype.     

Genetic defects as important factors for moderate hyperhomocysteinemia.

The genes for the enzymes methylenetetrahydrofolate reductase (MTHFR), methionine synthase (MS), methionine synthase reductase (MSR) and cytathionine-beta-synthase (CBS) play an important role in homocysteine metabolism. Rare mutations in these genes cause severe hyperhomocysteinemia and clinical symptoms. Growing interest has focused on common mutations with moderate effects on homocysteine levels. We studied 280 subjects of different age groups for the following mutations: MTHFR677C-->T and 1298A-->C, MS2756A-->G, MSR66A-->G and the 68 bp insertion in the CBS gene. The median value for homocysteine increased significantly with age (median homocysteine levels: 7.5, 12.4 and 16.5 micromol/l in the age groups 20-43, 65-75 and 85-96 years, respectively). The genotypes of the MTHFR677C-->T mutation were associated with differences in plasma homocysteine levels, but without reaching significance. Individuals homozygous for the MTHFR677C-->T mutation had a 2.3 micromol/l higher median homocysteine level compared to individuals with the wild-type allele. This effect was pronounced in combination with low folate levels and abolished with higher folate in plasma. For the other three mutations no association with homocysteine values could be determined. The analysis of homocysteine metabolite cystathionine by backward regression analysis revealed a significant correlation of the MS2756A-->G mutation with cystathionine level. This increase could indicate a disturbed remethylation. In summary, larger and homogeneous study populations are necessary to quantify the small effects of common mutations on homocysteine levels. This may also be the reason that no effects of genetic interactions between two genotypes were observed.     

5,10-Methylenetetrahydrofolate reductase 677C-->T and 1298A-->C mutations are genetic determinants of elevated homocysteine

BACKGROUND: Methylenetetrahydrofolate reductase (MTHFR) is one of the main regulatory enzymes of homocysteine metabolism. Elevated plasma total homocysteine (tHcy) is a major risk for cardiovascular disease. A common 677C-->T mutation in the MTHFR gene results in decreased enzymic activity, and contributes to increased plasma tHcy, in association with low plasma folate. A recently described 1298A-->C mutation in the MTHFR gene clearly reduces MTHFR activity (although to a lesser extent than the 677C-->T) but its effect on plasma tHcy levels is not yet clear. AIM: To investigate the frequency of these two MTHFR polymorphisms in a Portuguese population, and to correlate the MTHFR genotype with the biochemical phenotype at the level of homocysteine and folate concentrations. DESIGN: Prospective population survey. METHODS: We studied 117 healthy volunteers (71 females, 46 males). The 677C-->T and 1298A-->C mutations were screened by PCR-RFLP. Levels of plasma tHcy and folate, and red blood cell folate, were determined. RESULTS: The allele frequencies of the 677C-->T and 1298A-->C mutations were 0.33 and 0.28, respectively. Homozygotes for the 677C-->T mutation had significantly elevated plasma tHcy and RBC folate levels and significantly lowered plasma folate concentrations than subjects without the mutation. The 1298A-->C mutation showed a significant effect on plasma tHcy, but not on plasma folate or RBC folate levels. DISCUSSION: The observed 677T allele frequency is not consistent with the idea of a north-south gradient as previously suggested. The 1298A-->C mutation is common in Portugal. Both MTHFR mutations showed effects on plasma tHcy levels.     

Hyperhomocysteinemia is related to residual glomerular filtration and folate, but not to methylenetetrahydrofolate-reductase and methionine synthase polymorphisms, in supplemented end-stage renal disease patients undergoing hemodialysis.

Glomerular filtration is one of the major determinants of plasma total homocysteine (tHcy). To evaluate the respective roles of residual glomerular filtration (by measuring a specific protein marker, cystatin C), genetic polymorphisms and nutritional status in tHcy blood levels in end-stage renal disease patients (ESRD) under hemodialysis and supplemented with folate, we measured tHcy, folate, vitamin B12 (B12), creatinine, cystatin C, albumin and C-reactive protein and determined the polymorphism of methylenetetrahydrofolate reductase (MTHFR) (C677T and A1289C) and of methionine synthase (MS) (A2756G) in 114 ESRD patients before hemodialysis and 76 control subjects. All patients received a folate supplementation of 700 microg/day. Hyperhomocysteinemia was observed in all patients and exceeded the upper normal limit by 2-fold in 52.4% of the patients. Serum folate was significantly increased and the B12 level was not different from controls. Folate, Cystatin C and creatinine were significantly correlated to tHcy, while no correlation was found between tHcy, albumin and C-reactive protein. No difference in genotype frequency between ESRD patients and controls was found for MTHFR A1289C and MS A2756G. The MTHFR 677TT genotype was less frequent and was associated with a significantly higher tHcy level in patients. Folate and residual glomerular filtration estimated by cystatin C and creatinine levels were two independent determinants of tHcy in ESRD patients. These data suggest that hyperhomocysteinemia is a consequence as well as a complicating factor of renal failure.     

脑梗死患者同型半胱氨酸、5,10-亚甲基四氢叶酸还原酶基因多态性与颈动脉粥样硬化的相关性

目的探讨脑梗死患者急性期血清同型半胱氨酸（homocysteine,Hcy）、5,10-亚甲基四氢叶酸还原酶（methylenetetrahydrofolate,MTHFR）基因多态性与颈动脉粥样硬化之间的相关性。方法研究共纳入90例急性脑梗死患者和40例正常人,用循环酶法测定血清Hcy水平;用彩色多普勒超声检查颈动脉颅外段;采用聚合酶链反应-限制性内切酶片段长度多态性方法检测MTHFR基因型多态性。结果病例组颈总动脉（CCA）及颈内动脉（ICA）内中膜厚度（IMT）较对照组显著增厚（1.07±0.30）mm vs（0.87±0.33）mm,（1.00±0.31）mm vs（0.65±0.16）mm（均P〈0.01）。病例组较对照组颈动脉斑块发生率显著增高（74.4%vs 45.0%,P〈0.01）。病例组中不稳定斑块占所有斑块的比例较对照组中有增高的趋势,但差异无统计学意义（P〉0.05）。C/C、C/T、及T/T基因型人群血清Hcy水平分别为12.95（9.50~16.58）μoml/L,19.08（12.05~25.63）μoml/L,28.32（18.00~36.80）μoml/L,呈递增趋势,各组间差异有统计学意义（均P〈0.05）。Logistic回归分析显示在校正了传统的危险因素后,Hcy仍然是颈动脉粥样硬化的独立危险因素（P〈0.01）;MTHFRC677T基因多态性未进入回归方程。结论血清Hcy升高是脑梗死独立危险因素;MTHFRC677T基因多态性与颈动脉粥样硬化无相关性。     

MTHFR基因多态性和同型半胱氨酸在冠心病脑梗死和糖尿病中的分析

目的探讨冠心病、脑梗死、糖尿病患者亚甲基四氢叶酸还原酶（MTHFR）和血浆同型半胱氨酸（Hcy）的关系,对三个病种的MTHFR基因型进行分析。方法收集120例冠心病,214例脑梗死,112例糖尿病患者及98例健康体检者标本,采用聚合酶链式反应-限制性片段长度多态性（PCR-RFLP）技术检测MTHFRC677T基因,采用酶循环法检测血浆Hcy,比较四组MTHFRC677T基因多态性及血浆Hcy的差异。结果（1）MTHFR基因型在冠心病,脑梗死和糖尿病组与健康对照组间差异无统计学意义（P＝0．670）;（2）MTHFR基因频率在冠心病,脑梗死和糖尿病组与健康对照组间差异无统计学意义（P＝0．721）;（3）冠心病组和脑梗死组的MTHFR基因TT型患者的Hcy水平远远高于CC型和CT型患者（F＝6．212,P＝0．003;F＝44． 362,P＝0．000）。结论不同病种间MTHFR基因型和基因频率差异无统计学意义,但冠心病组和脑梗死组MTHFR基因TT型患者Hcy水平则远远高于CC型和CT型患者,差异有统计学意义。     

Molecular analysis of homocystinuria in Brazilian patients

BACKGROUND: Cystathionine beta-synthase (CBS) deficiency is the most common cause of homocystinuria. However, no data are available concerning the molecular basis of this disease in Brazilian populations. METHODS: We studied 14 Brazilian patients from 11 unrelated families using a combined screening approach, involving restriction analysis, single-strand conformational polymorphism (SSCP) scanning, and sequencing. RESULTS: All patients presented homocysteine levels higher than 200 mumol/l before the beginning of treatment. The most common CBS gene mutations, p.G307S (c.919G > A) and p.I278T (c.833T > C), were evaluated and the allele c.919A was not found. One allele with the c.844 ins68 (4.5%) in the CBS gene was found. Three families (6 patients) presented the allele c.833 C (13.6%), without the insertion in the heterozygous state. SSCP scanning and sequencing showed 3 alleles p.T191M (13.64%) in 2 families. One allele with a novel mutation was found in exon 4 (c.168T > A) of the CBS gene (4.5%). We also analyzed c.677C > T and c.1298A > C polymorphisms in the methylenetetrahydrofolate reductase (MTHFR) gene and the 2756A > G polymorphism in the methionine synthase (MTR) gene. The frequencies of mutated alleles were: 50% c.677T and 18.2% c.1298C for MTHFR, and 27.3% c.2756G for MTR. CONCLUSION: In spite of the high level of racial mixing in the country, Brazilian homocystinuric patients did not present a high prevalence of the most common mutations described in the literature.     

颈动脉粥样硬化超声表现与同型半胱氨酸及MTHFR基因多态性的相关性

目的 探讨颈动脉粥样硬化超声表现与血浆同型半胱氨酸(Hcy)及MTHFR C677T基因多态性之间的相关性。方法 143例颈动脉粥样硬化患者作为动脉硬化组,再进一步细分为内膜增厚亚组(75例)与斑块亚组(68例),选择91名无颈动脉内膜增厚及斑块形成者作为对照组。对所有研究对象均进行血浆Hcy及MTHFR C677T基因多态性检测。结果 MTHFR C677T基因CC、CT及TT型血浆Hcy水平依次逐渐升高,各组间差异有统计学意义(P<0.05)。血浆Hcy是颈动脉粥样硬化的独立危险因素(P<0.05),而MTHFR C677T基因多态性未进入回归方程。结论 血浆Hcy升高是颈动脉粥样硬化的独立危险因素;MTHFR C677T基因多态性在颈动脉粥样硬化与正常人群中分布不同,并与血浆Hcy水平相关,但不是颈动脉粥样硬化的独立危险因素。