MTHFR、TS联合作用与ALL患儿HD-MTX化疗毒副作用的关系

目的：探讨 MTHFR、TS基因多态性联合作用对ALL患儿HD-MTX化疗后不良反应的影响,以及与MTX血药浓度变化之间的关系;分析MTHFR、TS基因多态性联合作用在个体化治疗及疾病防治中的作用。方法 ALL患儿73例,提取其基因组DNA,PCR扩增后测序鉴定MTHFR C677T、MTHFR A1298C、TS 5’-UTR的基因型。观察所有ALL患儿HD-MTX化疗后的毒副作用,并监测MTX血药浓度。以Logistic 回归分析基因多态性与化疗毒副作用的危险度;采用Fisher精确概率法比较 HD-MTX 化疗后 MTHFR C677T、MTHFR A1298C、TS 的不同基因型之间42～48 h MTX血药浓度的差异,以P＜0.05为差异有显著性。结果（1）MTHFR677 CT／TT合并1298 AC／CC基因型者,其血红蛋白降低发生的风险下降了2.9倍,而黏膜损害发生的风险则增加了4.3倍,但差异均无显著性。（2）MTHFR1298 AC／CC合并TS 3R／3R基因型者,其发生黏膜损害的风险增加了5.4倍,差异有显著性（χ2＝4.911,P＝0.027）。（3）MTHFR677 CT／TT合并TS 3 R／3R基因型与HD-MTX化疗毒副作用的发生无关。（4）MTHFR677 CT／TT＋MTHFR1298 AC／CC＋TS 3 R／3 R基因型者,其黏膜损害发生的风险增加了7.5倍,且差异有显著性（χ2＝5.295,P ＝0.021）。结论 TS和MTHFRC677T基因多态性可与ALL患儿HD-MTX化疗后黏膜损害的发生有关。     

Analysis of MTHFR 1298A>C in addition to MTHFR 677C>T polymorphism as a risk factor for neural tube defects in the Turkish population

Maternal folic acid intake in the periconceptional period is strongly related to reduction in recurrence and occurrence of birth defects involving the neural tube. Among the single nucleotide polymorphisms (SNPs) influencing the folate metabolism, the methylenetetrahydrofolate reductase (MTHFR) gene has been the one most exclusively studied. Many studies have reported significant association between MTHFR 677C>T and increased risk of neural tube defects (NTDs). Our previous study did not support this observation. The present study aimed to determine the prevalence of 1298A>C polymorphism in addition to 677C>T in the same Turkish population as a risk factor for NTDs. We genotyped case (95 offspring with NTDs, 80 mothers, 72 fathers) and control (93 healthy children) populations for MTHFR 677C>T and MTHFR 1298 A>C polymorphisms. The comparison demonstrated a significant increase in the 1298AA/677TT genotype frequency among mothers of offspring with NTDs (OR 5.23 [1.06-25.9]; p=0.067). The 677CT genotype was only 1.35 times higher than controls among mothers when 677C>T polymorphism was evaluated alone, while 677CT/1298AC in the current study demonstrated a 3.8 times increase in this risk. These observations led us to conclude that although not statistically significant, MTHFR 1298AC polymorphism might be a risk factor for the occurrence of NTDs in the Turkish population.     

急性淋巴细胞白血病患儿亚甲基四氢叶酸还原酶基因多态性与大剂量甲氨蝶呤不良反应的相关性

目的探讨急性淋巴细胞白血病(ALL)患儿亚甲基四氢叶酸还原酶(MTHFR)基因677位点多态性与大剂量甲氨蝶呤(HDMTX)体内排泄及不良反应的相关性。方法 2008年3月-2010年2月在本院儿科中心和血液内科住院的完全缓解并接受HDMTX治疗的40例ALL患儿,在接受HDMTX治疗前应用PCR-限制性酶切片段长度多态性(RFLP)技术检测MTHFR基因C677T多态性,在HDMTX静脉输注开始后24 h、48 h应用荧光偏振免疫法(FPIA)测定其血浆MTX水平,密切观察ALL患儿HDMTX化疗后的不良反应,对化疗不良反应进行分级。对MTHFR677的基因多态性与MTX不良反应及HDMTX 48 h的MTX水平(MTX-48 h)的相关性进行分析。结果在有HDMTX相关不良反应的ALL患儿中,肝损害和骨髓抑制发生率最高。MTHFR C677T有肝脏损害的基因型分布频率由低到高为CC型40.0%,TT型60.0%,CT型80.0%,CT基因型者肝脏损害发生的风险是CC基因型者的6倍(OR=6.00,95%CI:1.05～34.32,P=0.044);677CT+TT基因型者肝脏损害发生的风险是CC基因型者的4.13倍(OR=4.13,95%CI:1.02～16.67,P=0.047)。MTHFR C677T基因型与骨髓抑制无明显相关性。携有MTHFR突变基因型(CT+TT)患者的48 hMTX血药质量浓度明显高于携带MTHFR野生型基因CC者(P=0.006)。结论 MTHFR 677位基因型可作为ALL患儿HDMTX化疗不良反应和药物体内排泄的有效预测指标。     

5，10-亚甲基四氢叶酸还原酶基因C677T多态性与先天性心脏病关系的Meta分析

摘要 目的 对5,10 亚甲基四氢叶酸还原酶（MTHFR）基因C677T多态性与先天性心脏病（CHD）的相关性研究进行Meta分析。方法 制定原始文献的纳入标准及检索策略,检索PubMed、EMBASE、Ovid、Springer、中国期刊全文数据库、维普中文科技期刊数据库、万方数据库和中国生物医学文献数据库（1994年1月至2009年1月）中的文献,收集MTHFR基因C677T多态性与CHD相关性的病例 对照研究,剔除不符合要求的文献,应用RevMan 4.2软件进行Meta分析,得出合并后的OR值及其95％CI。结果 共18篇文献符合纳入标准进入Meta分析。数据合并结果显示,子代MTHFR基因 677位点TT/CC和(TT+CT)/CC与CHD易感性有统计学意义,OR值（95％CI）分别为1.55（1.24~1.93）和1.23（1.06~1.42）,P<0.05;子代MTHFR基因677位点CT/CC与CHD易感性无统计学意义,OR值（95％CI）为1.15（0.99~1.34）,P>0.05。父亲MTHFR基因677位点TT/CC和(TT+CT)/CC与子代CHD的易感性有统计学意义,OR值（95％CI）分别为1.84（1.23~2.74）和1.33（1.04~1.71）,P<0.05;父亲MTHFR基因677位点CT/CC与子代CHD易感性无统计学意义,OR值（95％CI）为1.25（0.96~1.62）,P>0.05 。母亲MTHFR基因677位点TT/CC、CT/CC和(TT+CT)/CC与子代CHD易感性均无统计学意义,OR值（95％CI）分别为1.20（0.92~1.56）、1.03（0.86~1.24）和1.07（0.90~1.27）,P均>0.05。传递不平衡分析未发现在CHD核心家系的MTHFR基因677位点存在突变的传递不平衡现象,OR值为0.90（95％CI：0.79~1.12）,P>0.05。结论 子代MTHFR基因677位点TT和TT+CT为CHD的危险因素之一;父亲MTHFR基因677位点TT和TT+CT是子代CHD的危险因素之一;母亲MTHFR基因677位点多态性与子代CHD的发生无关。     

急性淋巴细胞白血病患儿MTHFR基因多态性与大剂量甲氨蝶呤毒副反应的关系

目的：探讨亚甲基四氢叶酸还原酶（MTHFR）基因单核苷酸多态性对急性淋巴细胞白血病（ALL）患儿使用大剂量甲氨蝶呤（HD-MTX）化疗后毒副反应的影响。方法：应用RT-PCR-变性梯度凝胶电泳结合DNA测序技术,对52例ALL患儿MTHFR C677T、A1298C和G1793A基因型进行检测。按照国立癌症研究所常规毒性判定标准（NCI-CTC）对患儿HD-MTX化疗后的不良反应统一评价。结果：MTHFR 1298AC基因型患儿发生血小板减少的风险较AA型提高了13.7倍（OR=13.7,95%CI=1.18～159.36,P=0.036）。MTHFR C677T和G1793A各基因型发生各类HD-MTX化疗不良反应的差异无统计学意义（P>0.05）。结论：MTHFR A1298C多态性可能与ALL患儿HD-MTX化疗后的毒副反应相关。     

Methylenetetrahydrofolate reductase and methionine synthase reductase gene polymorphisms and protection from microvascular complications in adolescents with type 1 diabetes

Abstract:  Folate status has been associated with endothelial dysfunction in adolescents with type 1 diabetes, and elevated total plasma homoocyst(e)ine (tHcy) is a risk for vascular disease in the non-diabetic population. Polymorphisms in genes involved in folate and homocysteine metabolism are implicated in vascular disease. We aimed to determine whether polymorphisms in the methylenetetrahydrofolate reductase (MTHFR) and methionine synthase reductase (MTRR) genes are risk factors for early microvascular disease in a large group of adolescents with type 1 diabetes. Four hundred and eighty adolescents were screened annually for retinopathy and microalbuminuria for a median of 4 yr. Molecular analysis for the polymorphisms 677C→T, 1298A→C in MTHFR, and 66A→G in MTRR was performed. The MTRR 66GG genotype reduced the risk for elevated albumin excretion rate (AER) (OR 0.47, CI 0.25, 0.88, p = 0.018) and showed a trend to reduced risk for microalbuminuria (OR 0.27, CI 0.06–1.21, p = 0.09). Survival without elevated AER was increased with the MTRR 66GG genotype (12.4 vs. 9.7 yr, p = 0.04) and with the MTHFR 1298CC genotype (15.2 vs. 10.2 yr, p = 0.007). Conversely, survival without retinopathy was reduced with the MTHFR 677TT and MTRR 66GG combined genotype (6.2 vs. 10.2 yr, p = 0.015). The MTRR 66GG and MTHFR 1298 CC genotypes may confer protection against early nephropathy, possibly because they are associated with lower tHcy. The MTHFR 677 TT was only related to earlier onset retinopathy in combination with MTRR 66GG.     

The MTHFR C677T and A1298C polymorphisms and susceptibility to childhood acute lymphoblastic leukemia in Portugal

Methylenetetrahydrofolate reductase (MTHFR) is an essential enzyme in folate metabolism and in DNA methylation and synthesis. The role of two common polymorphisms at the MTHFR gene, C677T and A1298C, in the etiology of childhood or adult acute lymphoblastic leukemia (ALL) has been previously investigated. Although a protective effect of MTHFR*677T against ALL was systematically reported, the magnitude of the effect appeared to be influenced by population-specific gene-environmental interactions. The evidence of the role of MTHFR*1298C in ALL susceptibility was less consistent, emphasizing the need for enlarging molecular epidemiologic studies to independent trials from different populations. The authors analyzed in North Portugal the association between variations at the two MTHFR positions and risk of ALL by comparing genotypes and gene frequencies in 103 affected children with those in 111 healthy controls. None of the variations was found to significantly affect the risk of developing childhood ALL in North Portugal, and this finding per se is of relevance in further studies aimed at assessing the etiology of the pathology in this specific population. Despite the absence of statistical significance, these data revealed that the frequency of MTHFR*677T was lower in patients than in controls, a result that is congruent with other reports and with the functional model usually invoked to explain its ALL protective effect. Concerning MTHFR1298*C, this study failed to corroborate previous findings of decreased risk of ALL in the presence of the variant.     

Influence of MTHFR and RFC1 polymorphisms on toxicities during maintenance chemotherapy for childhood acute lymphoblastic leukemia or lymphoma

We investigated preliminarily whether methylenetetrahydrofolate reductase (MTHFR) 677C/T or reduced folate carrier 1 (RFC1) 80G/A polymorphisms were associated with toxicities during maintenance chemotherapy with mercaptopurine (6MP) and methotrexate (MTX) in children with acute lymphoblastic leukemia or lymphoblastic lymphoma. The clinical records of 20 children (2 to 15-y old) who had received maintenance chemotherapy were reviewed retrospectively and their genomic DNA was genotyped to identify polymorphisms at MTHFR 677C/T, RFC1 80G/A, and thiopurine methyltransferase 719A/G. Maintenance chemotherapy with 6MP and MTX was repeated on a weekly basis, and any week during which 6MP and/or MTX dosing was withheld was counted as an interrupted episode. Associations between the risk of interruptions and polymorphisms were studied using a generalized estimating equation analysis. Patients with an increasing number of T alleles at MTHFR 677C/T experienced interruptions in both 6MP (P<0.01) and MTX (P=0.03) more frequently. Patients with an increasing number of A alleles at RFC1 80G/A experienced interruptions in 6MP (P=0.04) more frequently. This preliminary study does not prove but suggests that MTHFR 677C/T and RFC1 80G/A polymorphisms may serve as predictors of toxicity during maintenance chemotherapy.     

Cardiovascular fitness is negatively associated with homocysteine levels in female adolescents

OBJECTIVE: To examine the association between cardiovascular fitness and homocysteine levels in adolescents. DESIGN: Cross-sectional study. SETTING: Madrid, Murcia, Granada, Santander, and Zaragoza, Spain. PARTICIPANTS: One hundred fifty-six Spanish adolescents (76 boys and 80 girls) aged (mean +/- SD) 14.8 +/- 1.4 years. MAIN EXPOSURES: Cardiovascular fitness was measured by the 20-m shuttle run test. Pubertal stage, birth weight, smoking status, and socioeconomic status were determined, and the sum of 6 skinfold thickness measurements, and serum folic acid and vitamin B(12) levels were measured. Methylenetetrahydrofolate reductase (MTHFR; 677C>T genotype) polymorphism was done by DNA sequencing. MAIN OUTCOME MEASURE: Fasting homocysteine levels. RESULTS: Mean values of homocysteine were significantly higher in the MTHFR 677CT and TT genotype subgroups compared with the CC genotype subgroup in adolescent boys, whereas in adolescent girls, mean values of homocysteine were significantly higher in the MTHFR 677CT and TT genotype subgroup compared with the CC and CT genotype subgroups. Multiple regression analyses showed that cardiovascular fitness was significantly associated with homocysteine levels in female adolescents after controlling for potential confounders including the MTHFR 677C>T genotype (beta = -0.40; semipartial correlation = -0.35; P = .007). No associations were found between cardiovascular fitness and homocysteine levels in male adolescents (beta = 0.12; semipartial correlation = 0.08; P = .51). CONCLUSION: The results suggest that cardiovascular fitness is negatively associated with homocysteine levels in female adolescents after controlling for potential cofounders including MTHFR 677C>T genotype.     

Total homocysteine, folate, and cobalamin, and their relation to genetic polymorphisms, lifestyle and body mass index in healthy children and adolescents

We investigated total homocysteine (tHcy) concentrations and relations between tHcy and folate, cobalamin (Cbl), genetic polymorphisms (MTHFR 677C > T, MTHFR 1298A > C, MTHFR 1793G > A), blood pressure (BP), body mass index (BMI), cholesterol, triglycerides, sports activities, family and individual history of cardiovascular disease (CVD) and lifestyle issues in 264 healthy children and adolescents (2-17 y). THcy concentrations significantly increased while folate and Cbl decreased with age without gender differences. Age, folate and Cbl were significant predictors for tHcy concentrations. THcy was higher but within normal ranges in MTHFR 677TT homozygotes (10.6%) and carriers of the MTHFR 1793A allele (8%). Only two individuals (0.8%), both with low tHcy concentrations, were homozygous for MTHFR 1793AA. THcy concentration correlated positively with creatinine, triglycerides, BMI and systolic BP and was not related to cholesterol, sports activities and family history of CVD. In conclusion, tHcy concentrations in this pediatric population were significantly influenced by age, folate and Cbl concentrations. No gender differences for tHcy, folate or Cbl concentrations were observed. Both the MTHFR 677TT genotype and the MTHFR 1793A allele were not associated with hyperhomocysteinemia. The prevalence of the MTHFR 1793AA genotype was too low for meaningful interpretation.     

MTHFR基因多态性与儿童原发性高血压的相关性研究北大核心CSCD

目的分析原发性高血压儿童亚甲基四氢叶酸还原酶(methylenetetrahydrofolate reductase,MTHFR)基因C677T多态性分布特征,探讨其与儿童H型高血压的相关性。方法回顾性选取2021年1~7月于心血管内科住院、初次诊断未经治疗的121例原发性高血压儿童为研究对象,按基因型分为CC型组(19例)、CT型组(51例)和TT型组(51例);按血清同型半胱氨酸(homocysteine,Hcy)水平分为H型高血压组(47例)和单纯高血压组(74例),比较各组间临床资料差异,分析MTHFR基因C677T多态性与儿童H型高血压的相关性。结果原发性高血压儿童T等位基因突变频率高于北京地区健康成年人群和中国汉族成年人群(P<0.001)。TT型组血清Hcy水平高于CC型组和CT型组(P<0.001)。H型高血压组血清Hcy水平高于单纯高血压组(P<0.001),且MTHFR基因C677T多为TT基因型,TT基因型与H型高血压的发生风险存在关联(OR=12.71,P<0.001)。H型高血压组和单纯高血压组间靶器官损伤发生率差异无统计学意义(P>0.05),但初次诊断时,H型高血压组即可存在多脏器受累情况,占11%(5/47)。结论原发性高血压儿童MTHFR基因C677T的T等位基因突变率高且与血清Hcy水平具有一定关联,TT基因型是儿童H型高血压的独立危险因素,与早期靶器官损伤严重程度可能相关。     

Genetic risk factors of bronchopulmonary dysplasia

The aim of the study was to assess the association between bronchopulmonary dysplasia (BPD) and polymorphisms of genes coding for vascular endothelial growth factor (VEGF), transforming growth factor (TGF-[beta]1), insulin-like growth factor (IGF-1), and 5,10-methylenetetrahydrofolate reductase (MTHFR). A sample of 181 newborns with mean gestational age of 28 wk was prospectively evaluated. Molecular analysis of TGF-[beta]1 -800G>A, -509C>T, 10T>C, 25G>C, VEGF -460T>C and 405G>C and MTHFR 677C>T polymorphisms were performed and the number of CA repeats in the promoter region of IGF-1 gene was assessed. The frequency of all TGF-[beta]1, IGF-1, and MTHFR polymorphisms, as well as the frequency of VEGF 405G>C polymorphism was similar in all groups. The newborns with -460TT and -460CT genotypes were significantly overrepresented in the BPD groups compared with the no BPD group. Multivariate analysis revealed that carrying T allele increased the risk of BPD by 9% (95%CI: 2-14%) above the baseline risk established for given gestational age, length of oxygen therapy, and sex. Based on our data from a single center, we propose that VEGF -460T>C polymorphism may influence the risk of BPD.     

中国心脏圆锥动脉干缺损患儿MTHFR基因C677T突变研究(英文)

目的：心脏圆锥动脉干缺损(CTD)是一组严重的、复杂的青紫型先天性心脏病。N5, 10 亚甲基四氢叶酸还原酶(MTHFR)是参与甲硫氨酸-叶酸代谢的关键酶,其基因677位点C→T错义突变可造成此酶活性降低,导致高同型半胱氨酸血症,现已证明高同型半胱氨酸是诱发胎儿出生缺陷和心血管疾病的一个独立危险因素。本研究旨在了解中国CTD患儿MTHFR基因C677T位点突变的情况。方法：用多聚酶链反应限制性内切酶片段长度多态性技术(PCR RFLP)检测97例CTD患儿和118例正常健康人MTHFR基因677位点C→T突变多态性,并比较两组677TT的纯合突变率。结果：CTD患儿中TT基因型频率为24. 7% (24 /97),显著高于对照组13. 6%,χ2 = 4. 40,P= 0. 036,OR值2. 1(95% CI: 1. 04~4. 22);CTD患儿组T等位基因频率为52. 6%,显著高于对照组42. 8%,χ2 = 4. 09, P= 0. 043,OR值1. 5(95% CI: 1. 01~2. 17)。其中法洛氏四联症、主动脉缩窄、主动脉弓离断的TT基因型频率为29. 7% ~40. 0%。结论：MTHFR基因与心脏圆锥动脉干缺损有一定关系,其677TT基因型可能是引起先天性心脏畸形的危险因素之一。     

Polymorphism 677C→T MTHFR Gene in Mexican Mothers of Children With Complex Congenital Heart Disease

Congenital heart defects (CHD) are the third leading cause of death in children <1 year of age in Mexico where there is a high prevalence of the 677C→T polymorphism of the MTHFR gene. This is important because the homozygous 677T/T MTHFR gene and deficiency of folic acid (FA) intake have been associated with CHD. Our objective was to analyze the possible association between the genotype 677T/T of the MTHFR gene and supplementation of FA in Mexican women with the presence of complex CHD in their children. We analyzed genotypes of 31 mothers of children with complex CHD (group I) and 62 mothers of healthy children (group II) and investigated FA supplementation during pregnancy in both study groups. Allele frequencies in group I were 41.9 % for C and 58.1 % for T and 22.6 % for genotype frequencies CC, 38.7 % for CT, and 38.7 % for TT. Allele frequencies in group II were 63.7 % for C and 36.3 % for T and 38.7 % for genotype frequencies CC, 50 % for CT and 11.3 % for TT. Both populations are in Hardy–Weinberg equilibrium. Odds ratio for having a child with a complex CHD was 5.9, p = 0.008 (95 % CI 1.67; 20.63) for the TT genotype. FA supplementation at any time during pregnancy was 90.3 and 87.9 % in groups II and I respectively (p > 0.05). Association was found between the maternal genotype (677/TT MTHFR) with the presence of complex CHD in their offspring. No differences in FA supplementation during any stage were found between groups.     

Methylene tetrahydrofolate reductase mutations as genetic risk factors for neural tube defects (NTF)

Folic acid supplementation before conception and during the first trimester of pregnancy prevents about 70% of all neural tube defects (NTD). Folic acid is a cofactor in the homocysteine metabolism. Its product--S-adenosylmethionine is a major methyl donor for reactions taking place in a cell. The 677 C-->T mutation in the methylene tetrahydrofolate reductase gene leads to thermolability and decreased activity of the enzyme. In the individuals homozygous for that mutation hyperhomocystynemia and lowered plasma folate level are observed. Presence of the MTHFR 677 C-->T mutation increases the requirements for folic acid, especially at the time of rapid foetal growth. Studies showed higher rate of TT homozygotes in people with NTD and their parents compared with the control group. Hyperhomocystynemia has been associated with higher risk of recurrent miscarriages in women. It was also proved that stillbirths are a risk factor associated with NTDs. TT homozygosity varies among different country populations, from 6% to 16%. An additional risk factor for NTD is MTHFR 1298 A-->C mutation. Combined heterozygosity for the 1298 A-->C and 677 C-->T mutations is associated with increased homocysteine and lowered plasma folate levels. This genotype is more frequent in NTD patients compared with controls. Further investigations in the field of genetic aspects of NTD in Poland will be very important for the primary prevention of NTD.     

MTHFR C677T and A1298C polymorphisms as a risk factor for congenital heart defects in Down syndrome

Background: Congenital heart defects (CHD) are present in most, but not all, cases of Down syndrome (DS). The presence of methylenetetrahydrofolate reductase (MTHFR) C677T and A1298C polymorphisms has been reported as a risk factor for CHD in DS. The aims of the present study were to assess (i) the frequency of MTHFR C677T and A1298C polymorphisms in DS individuals in the Croatian population; (ii) the relationship between the two maternal MTHFR polymorphisms and CHD‐affected DS children; and (iii) the transmission frequencies of the variant alleles of the two MTHFR polymorphisms in CHD‐affected DS. Methods: The study population included 112 DS subjects and 221 controls. CHD were present in 48% of the DS subjects (54/112). The mothers of 107 DS individuals were available for the study; none was a periconceptional folic acid user. Allele transmission was analyzed in 34 complete parent–offspring triads. Results: The frequencies of the allele, individual, and combined genotypes of MTHFR C677T and A1298C in DS subjects were not statistically different compared to the normal healthy Croatian controls. The maternal MTHFR polymorphisms were not found to be a risk factor for DS‐related CHD. The allele transmission of the two MTHFR polymorphisms showed no deviations from random segregation. Conclusions: Because the fetus is lost in a great proportion of trisomy 21 pregnancies, both maternal and fetal, not only live‐born MTHFR C677T and A1298C, as well as maternal nutrition and lifestyle during pregnancy, should be analyzed to asses the impact on CHD in DS.     

支气管哮喘患儿亚甲基四氢叶酸还原酶基因多态性与血清免疫球蛋白E的关系

目的探讨支气管哮喘(哮喘)患儿亚甲基四氢叶酸还原酶(MTHFR)基因C677位点多态性与血清IgE水平的相关性。方法选择95例哮喘患儿作为病例组,均为急性发作期或临床缓解期哮喘患儿,患病前2周均未使用过肾上腺皮质激素及免疫调节剂。另选择健康儿童113例作为健康对照组。2组儿童年龄及性别比较差异均无统计学意义。采用PCR-限制性片段长度多态性分析法对病例组和健康对照组儿童外周血白细胞MTHFR基因C677位点基因多态性进行研究,应用双抗体夹心ELISA法检测2组儿童血清总IgE水平。结果健康对照组MTHFR 677C/T的3种基因型频率分别CC 35.4%、CT 45.1%、TT 19.5%,病例组分别为CC 24.2%、CT 40.0%、TT 35.8%,677C/T基因型分布频率在哮喘病例组和健康对照组间差异有统计学意义(χ2=7.556 5,P<0.05)。病例组T等位基因的频率为55.3%,健康对照组为42.0%,病例组较健康对照组显著增高,其患哮喘的危险度是健康对照组的1.71倍(χ2=7.254 7,P<0.01;95%CI:1.13～2.57)。病例组血清总IgE水平在各基因型患儿间比较差异有统计学意义(F=3.46,P<0.05),健康对照组血清总IgE水平在各基因型儿童间比较差异无统计学意义(F=0.13,P>0.05)。结论 MTHFRC677位点C→T的基因突变增加了患儿哮喘发病的危险度,TT基因型与哮喘的发生直接相关;哮喘患儿血清总IgE水平升高,该位点基因型并非导致血清总IgE水平升高的直接原因。     

Pediatric stroke and methylenetetrahydrofolate reductase polymorphisms: an examination of C677T and A1298C mutations

Although rare in children, stroke is becoming increasingly recognized as an important cause of morbidity and mortality with an annual incidence of approximately 3 per 100,000 per year. While several studies have documented the underlying mechanisms and pathogenesis related to stroke in adults, including genetic and acquired prothrombotic conditions, the data available on similar conditions in children is limited. Evidence suggests that mutations in methylenetetrahydrofolate reductase (MTHFR) appear to be linked with hyperhomocysteinemia (HHC) and cerebral-thrombotic events in children. While the C677T common missense mutation is the best-characterized MTHFR polymorphism, another common missense mutation, A1298C also exists. A recent study of children demonstrated that the homozygous form of C677T polymorphism occurred two-times as often in those with stroke versus healthy controls. In our retrospective chart review of 33 children seen at Children's Hospital of Orange County from January 1, 2000 to September 30, 2003 with the diagnosis of stroke, we examined both the C677T and A1298C polymorphisms for occurrence and type. In the subset (n=21), which excluded those with a confounding disorder, we observed a significant increase in the frequency of A1298C and C677T homozygosity (0.25 [p=0.01] and 0.20 [p=0.100], respectively); expected rate: (0.06 and 0.08, respectively). Our observed rates of heterozygosity for both MTHFR mutations (0.35 and 0.40, respectively) were consistent with expected rates (0.28 and 0.38, respectively). In all subjects, homocysteine (HC) levels were normal. The results of our study suggest that mutations in MTHFR are associated with pediatric stroke. However, additional studies are required to confirm our findings and to determine if this relationship is causal.     

Reduced total plasma homocyst(e)ine in children and adolescents with type 1 diabetes

OBJECTIVES: The objective was to investigate total plasma homocyst(e)ine (tHcy), methylenetetrahydrofolate reductase (MTHFR) genotype, and the contribution of diet to homocysteine values in children and adolescents with type 1 diabetes and a control group. STUDY DESIGN: A total of 78 children with type 1 diabetes and 59 members of an age- and sex-matched control group were recruited. Fasting samples were collected for tHcy, MTHFR genotype, serum vitamin B(12), serum folate, red cell folate, and plasma creatinine. Food frequency questionnaires targeted intake of folate, vitamin B(6), and vitamin B(12). RESULTS: Fasting tHcy was reduced in patients compared with the control group (4.7 vs 5.9 micromol/L, P <.001). Serum folate (P =.002), red cell folate(P <.001), and serum vitamin B(12) (P =.005) were higher, and plasma creatinine was lower. A significant difference in tHcy values between patients and the control group persisted after correction was done for these factors (r = 0.1, P =.02). No difference was seen in the frequency of MTHFR polymorphisms. tHcy was not elevated in those patients with the 677TT or 677T/1298C genotypes, although red cell folate was significantly higher in members of the case (P =.01) and control groups (P =.05) with a 677 TT genotype. Dietary intake of folate correlated with serum folate (r = 0.4,P =.005). CONCLUSION: tHcy values are lower in children and adolescents with type 1 diabetes. Higher serum levels of folic acid and vitamin B(12), reflecting differences in dietary intake between children with diabetes and members of a control group, partially account for this difference.     

Methylenetetrahydrofolate reductase C677T polymorphism: association with risk for childhood acute lymphoblastic leukemia and response during the initial phase of chemotherapy in greek patients

BACKGROUND: As of late, a number of studies have focused on the association of the gene for methyletetrahydrofolate reductase (MTHFR) with risk for acute lymphoblastic leukemia (ALL) in children and in adults, as well as with response to chemotherapy. The degree of this association may vary according to the ethnic background and geographic localization of the population under study, or the phase of treatment when response to chemotherapy is concerned. PROCEDURE: We have analyzed the MTHFR C677T polymorphism in 52 patients and 88 control individuals, all ethnic Greek residents of northern Greece, and examined the association of this polymorphism with (a) susceptibility to childhood ALL and (b) the distribution of average plasma alanine aminotransferase (ALT) levels, white blood cell counts (WBC), and hemoglobin levels (Hb) during the induction and consolidation phases of treatment. RESULTS AND CONCLUSIONS: We were able to detect a statistically significant protective effect, with respect to ALL, associated with carriage of the MTHFR 677T allele [OR = 0.387 (95% CI = 0.193-0.776)]. In addition, we observed a general tendency towards lower values in all three parameters studied, associated with the MTHFR 677CC genotype, which was more evident in the transition from the induction to the consolidation phase, indicating that MTHFR genotyping may be of prognostic value in the early phase of treatment for childhood ALL, in our population.