Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) in a Greek family

Abstract Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is an adult-onset inherited disease, characterised by recurrent strokes, migraine and cognitive impairment. We present the first Greek family with CADASIL, caused by the R153C mutation at exon 4 of the Notch3 gene. A member of this family carrying this mutation was also found to be heterozygotic for the MTHFR mutation, factor V Leiden mutation and had low serum levels of antithrombin III, thus resulting in the appearance of recurrent strokes and thrombotic episodes since his early adulthood. The co-existence of these thrombophilic disorders with CADASIL in a single person poses serious therapeutic dilemmas, as the administration of anticoagulant agents may correlate with increased risk of potentially fatal intracerebral haemorrhage.     

冠心病患者甲基四氢叶酸还原酶基因多态性的研究

目的 :探讨同型半胱氨酸(HCY)代谢相关酶甲基四氢叶酸还原酶 (MTHFR)基因多态性、血浆HCY、叶酸、维生素B12 水平与冠心病的关系。方法:用酶联免疫试剂盒测定血浆HCY ,放射免疫法测定维生素B12 和叶酸水平 ,以多聚酶链反应 -限制性内切酶片段长度多态性 (PCR -RFLP)分析MTHFRC677T基因型。结果:冠心病组MTHRR基因TT型、TC型及CC型频率分布及T、C等位基因频率与对照组无显著差异 (χ2=1.427,P>0.05;χ2=1.257,P>0.05)。冠心病组HCY水平为 (21.58±12.69)umol/L显著高于对照组(P<0.01)。叶酸浓度平均(2.78±1.66)ng/ml,维生素B 12 浓度平均 (231.76±143.78) pg/ml,明显低于对照组 (P<0.01)。冠心病组中3种基因型的HCY水平有显著差异 ,TT型HCY明显高于CC型 (P<0.05)。结论:高HCY血症是冠心病发病的危险因素 ,血浆HCY水平的升高与叶酸、维生素B12 的降低有关。MTHFR基因C677T的TT突变是高同型半胱氨酸血症的原因 ,但MTHFRC677T基因多态性与冠心病的发生无显著相关     

Association of acute ischemic stroke with the MTHFR C677T polymorphism but not with NOS3 gene polymorphisms in a Singapore population

Background and purpose: The association of polymorphisms in the nitric oxide synthase 3 (NOS3) gene (T‐786C, variable number tandem repeats 4A/B/C, and G894T) and in the methylenetetrahydrofolate reductase (MTHFR) gene (C677T) with acute ischemic stroke have been reported. Methods: First‐time onset acute ischemic stroke patients (n = 120) and controls (n = 207) with no past history of stroke were compared. Allele specific gene amplification and restriction fragment length polymorphism (RFLP) analysis were used to determine the genotype and allelic frequencies in both groups. Plasma homocysteine (Hcy) and nitrite levels were measured. Results: No significant association of NOS3 polymorphisms with ischemic stroke was noted. The TT genotype of the MTHFR C677T polymorphism was significantly associated with ischemic stroke (P = 0.004). Elevated plasma Hcy levels were also significantly associated with ischemic stroke (P = 0.001). Conclusions: The TT genotype of C677T polymorphism in the MTHFR gene contributes to genetic susceptibility of acute ischemic stroke in a Singapore population.     

Dietary folate is associated with p16(INK4A) methylation in head and neck squamous cell carcinoma

Inactivation of the p16(INK4A) (CDKN2A) gene in the Rb pathway is among the most common somatic alterations observed in tobacco-related solid tumors, including head and neck squamous cell carcinoma (HNSCC). In addition, a low folate diet is an important risk factor for HNSCC. Decreased dietary folate in an animal model of hepatocellular carcinoma has been associated with the induction of epigenetic silencing of the p16(INK4A) gene. In an ongoing population-based study of HNSCC, we sought to extend this observation to human disease testing the hypothesis that p16(INK4A) methylation is associated with decreased dietary folate. We also investigated the association of methylation silencing with functional polymorphisms in the folate metabolism enzyme methylene tetrahydrofolate reductase (MTHFR). In 169 HNSCCs, the odds ratio for p16(INK4A) methylation among those with low dietary folate intake was 2.3 (95% CI = 1.1-4.8) when compared with those with high folate intake. Furthermore, this increased risk for epigenetic silencing at p16(INK4A) was modified by the MTHFR alleles previously associated with diminished serum folate levels. Hence, in HNSCC low dietary intake of folate is associated with p16(INK4A) methylation, and this relationship is modified by the MTHFR genotype. Our data provides important evidence for a mechanism of action of folate deficiency in cancer.     

The thymidylate synthase tandem repeat promoter polymorphism: A predictor for tumor-related survival in neoadjuvant treated locally advanced gastric cancer

We evaluated DNA polymorphisms in the thymidylate synthase (TS) and 5,10-methylene-tetrahydrofolate reductase (MTHFR) genes for an association with response and survival in locally advanced gastric cancer treated with 5-FU based preoperative chemotherapy (CTx). DNA of 238 patients (CTx-group: total n = 135, completely resected (R0) n = 102; without CTx: R0 n = 103) was isolated from blood or from nontumorous tissues. In the CTx-group, genotyping of the tandem repeat and the G/C polymorphism in the triple repeat in the promoter region of the TS gene and of the C677T polymorphism of the MTHFR gene was performed. None of the TS or MTHFR genotypes were associated with histopathological response and only the TS tandem repeat polymorphism was significantly related to survival (all patients n = 135, p = 0.002; R0 resected patients n = 102, p = 0.007; log-rank test). Multivariate analysis revealed ypN (p < 0.001) and the TS tandem repeat polymorphism as independent prognostic factors in the CTx-R0-group (p = 0.003). Analyzing the prognostic significance of the TS polymorphisms in the R0-group without CTx, TS genotypes were not significantly associated with survival. Comparing survival between R0 patients with and without CTx in the respective TS genotype groups of the tandem repeat polymorphism, a significant survival benefit for the patients with CTx was found for the 2rpt/2rpt (n = 49; p = 0.002) and 2rpt/3rpt genotypes (n = 99; p = 0.004), but not for the 3rpt/3rpt genotype (n = 57; p = 0.93). Patients' survival after CTx was associated with the TS tandem repeat polymorphism. CTx did not improve survival of patients with the 3rpt/3rpt genotype. Thus, a different therapy might be more appropriate for these patients.     

Thrombophilic screening in young patients (< 40 years) with idiopathic ischemic stroke: a controlled study

Introduction

Despite extensive clinical and laboratory investigations, the etiology of ischemic stroke remains unknown in approximately one third of patients.

Materials and Methods

Thirty-four consecutive patients less than 40 years old (Males 13, Females 21, mean age 26.6 years, range 2-39) with documented ischemic stroke underwent, one year after the acute event, laboratory evaluation of antithrombin, protein C, free and total protein S, activated protein C resistance, fibrinogen, factor VII:C, homocysteine levels and antiphospholipid antibodies (APA). Moreover, prevalence of F5 R506Q, F2 G2021A and homozygosis for thermolabile variant C677T of the methylenetetrahydrofolate reductase (MTHFR) were also evaluated and compared to the results obtained in 120 normal controls.

Results

Antithrombin and protein C levels resulted normal in all cases. One patient (2.9%) showed free protein S deficiency and 3 patients (8.8%) had activated protein C resistance. Homocysteine levels above 15 μmol/L were found in one patient (2.9%). APA were found in 21 patients (61.7%) and in only 2 out of 120 (1.66%) controls (OR = 95.31; 95% C.I.: 18.22-667.81). The multivariate analysis selected that the presence of APA was significantly associated with an increased risk of stroke (OR = 156.60; 95% C.I.: 25.99-943.47) in this cohort of patients. The combination between APA and cardiovascular risk factors determined a risk of 29-fold (OR = 29.31; 95% CI: 3.28-261.69).

Discussion

Our data suggest that the presence of APA is associated with an increased risk of idiopathic ischemic stroke in young patients. Furthermore, also the combination of APA and cardiovascular risk factors is significantly associated with development of idiopathic ischemic stroke.     

Hereditary thrombophilia in ethnic Omani patients

Hereditary thrombophilias are a group of inherited conditions that predispose to thrombosis. Mutations like factor V Leiden, prothrombin gene variant 20210A, and hereditary hyperhomocysteinemia are associated with an increased risk for thromboembolism as compared to mutations in natural inhibitors of coagulation. There is also evidence that multiple defects co-exists in persons with a tendency for thrombosis. We studied prothrombotic determinants, namely protein C, protein S, and AT along with factor V Leiden (1691G-->A), prothrombin gene mutation (20210G-->A), CBS 844ins68 mutation, and MTHFR mutation (677C-->T) in consecutive ethnic Omani patients with first episode of a thrombophilic event, namely, deep vein thrombosis (DVT), and/or pulmonary embolism (PE) or thrombosis at an unusual site. Fasting plasma homocysteine was also analyzed. Factor V Leiden and the prothrombin gene mutation were not seen in any patient nor in any control subject studied. The thermolabile MTHFR mutation (677C-->T) was present in 14 patients (35.89%) whereas the CBS 844ins68 mutation was documented in 6 patients (15.38%); 3 patients were common in both groups. Six patients had low protein C (15.38%), two patients had low protein S (5.12%), but none had low AT levels. Interestingly, one patient had triple abnormality, namely, PC deficiency with both CBS 844ins68 mutation as well as the MTHFR mutation (677C-->T) whereas another two patients had the latter two mutations together. This data set, although small, reflects the importance of multiple screening strategies. The yield appears high, emphasizing the referral pattern to a tertiary health center. Of these patients, 43.58% had either or both the hyperhomocysteinemic mutations studied, whereas in 38.46% of these patients, no underlying cause for thrombophilia could be documented.     

MTHFR C677T Polymorphism and Risk of HCC in Patients With Liver Cirrhosis: Role of Male Gender and Alcohol Consumption

Background:  A single nucleotide polymorphism (SNP) C677T in the methylenetetrahydrofolate reductase (MTHFR) gene has been identified. The TT or CT genotypes show a marked reduction of the enzyme activity; this causes higher homocysteine levels and alterations of folate metabolism. Folate metabolism is essential for DNA synthesis and methylation, crucial steps in carcinogenesis. In this paper, we investigated whether the MTHFR C677T SNP could influence the occurrence of hepatocellular carcinoma (HCC) in a cohort of patients transplanted for end stage liver disease of different etiologies.
Methods:  Two hundred and twelve consecutive patients who underwent liver transplantation for end stage liver disease due to hepatitis B or C, alcoholic liver disease, and other causes were studied. Two hundred and thirty-six blood donors served as controls. Focal hepatic lesions were searched in the sectioned explanted livers. The presence of the MTHFR C677T SNP was determined via polymerase chain reaction amplification.
Results:  Among the 65 patients with HCC, 22 had the CC genotype, 30 the CT, and 13 the TT genotype. Only in patients with alcoholic liver disease was a significant association detected between the TT genotype and the presence of liver cancer (6/17 vs. 5/46, p  < 0.05). At stepwise logistic regression analysis the independent selected predictors of HCC were found: age at transplantation >55 years ( p  < 0.001) and the association among male gender, alcoholic liver disease, and MTHFR TT genotype ( p  = 0.002).
Conclusions:  The present study suggests that male TT carriers with alcoholic cirrhosis bear an increased risk of developing HCC.     

Lack of association between the MTHFR (C677T) polymorphism and atopic disease

Background: Impaired folate metabolism has been suggested as a potential risk factor for the development of asthma and atopic disease. However, there have been conflicting reports on the potential association between atopic disease and a common polymorphism of the methylene‐tetrahydrofolate reductase (MTHFR)‐gene, a well‐known marker of impaired folate metabolism. Objectives: The aim of this study was to investigate the association between the MTHFR (C677T) polymorphism and different outcome variables of asthma and atopic disease. Methods: This study was a population‐based study of 1189 participants aged 15–77 years living in Copenhagen, the Capital of Denmark. Examinations included measurements of specific IgE and skin prick tests against inhalant allergens, metacholine bronchial hyper‐reactivity, and serum eosinophilic cationic protein, and a self‐administered questionnaire about diagnoses and symptoms of allergy and asthma. In addition, participants were genotyped for the MTHFR (C677T) polymorphism. Results: None of the examined outcomes were significantly associated with the MTHFR (C677T) polymorphism. Conclusions: The results of this study using detailed objective markers of atopic disease do not support the hypothesis that impaired folate metabolism as reflected by the MTHFR genotype is involved in the development of atopic disease. Please cite this paper as: Thuesen BH, Husemoen LLN, Fenger M and Linneberg A. Lack of association between the MTHFR (C677T) polymorphism and atopic disease. The Clinical Respiratory Journal 2009; 3: 102–108.