Loci C677T and A1298C of the methylenetetrahydrofolate reductase gene and the risk of neural tube defects in the Kyrgyz population

Цель. Изучить ассоциацию полиморфных локусов С677Т и А1298С гена MTHFR с развитием дефектов нервной трубки (ДНТ) у детей киргизской национальности. Методы. В исследование включены 76 детей и их матери. В основную группу вошли 30 детей с пороками невральной трубки, чаще всего в виде изолированной спиномозговой грыжи или в сочетании с другими врожденными пороками развития, а также их матери. 46 детей без ДНТ и их матери составили контрольную группу. Идентификация генотипов полиморфных локусов С677Т и А1298С гена MTHFR проводилась методом анализа полиморфизма длин рестрикционных фрагментов (ПДРФ). Результаты. При анализе распределения генотипов и аллелей полиморфизма А1298С гена MTHFR выявлено, что среди детей с ДНТ статистически значимо чаще встречались гетерозиготный генотип А1298С (χ²=9,67; р=0,0079) и аллель 1298С (χ²=4,17; р=0,04). При наличии генотипа А1298С риск развития ДНТ повышается в 4,71 раза (OR=4,71; p=0,0079), а при наличии аллеля 1298С - в 2,2 раза (OR=2,20; p=0,04). Полиморфный локус С677Т гена MTHFR самостоятельно не был ассоциирован с ДНТ, однако гетерозиготность по двум полиморфным аллелям ассоциирована с ДНТ (χ²=5,60; p=0,018) и существенно повышает относительный риск развития ДНТ (OR=9,75; p=0,018). Заключение. У детей киргизской национальности полиморфный локус А1298С гена MTHFR ассоциирован с развитием дефекта нервной трубки. Комбинированная гетерозиготность (С677Т/А1298С) по обоим полиморфизмам является дополнительным отягощающим фактором. Aim. The aim of the study was to investigated whether polymorphisms С677Т and А1298С of the MTHFR gene are associated with neural tube defects (NTDs) in the Kyrgyz population. Methods. The study included 76 children and their mothers. The study group included 30 children and their mothers, where the child had a neural tube defect, most commonly in the form of an isolated spina bifida or in combination with congenital anomalies. Control group - 46 children without congenital malformations. С677Т and А1298С polymorphisms analysis in the MTHFR gene were performed by PCR-RFLP method. Results. The frequency of the heterozygous A1298C genotype (χ²=9,67; p=0,0079) and 1298C allele (χ²=4,10; p=0,041) of the MTHFR gene was higher in cases than in controls. Child with heterozygous A1298C genotype had a 4,71- fold (OR=4,71; p=0,0079) higher risk of NTDs when compared with those who had the AA genotype. Child carriers of the 1298C allele had a 2,2-fold higher risk of NTDs (OR=2,20; p=0,041). С677Т/А1298С genotypes are more frequent among cases than controls (χ²=5,00; p=0,025). We showed that the combinations of С677Т/А1298С is strong association with NTDs (χ²=5,60; p=0,018). Subjects carriers of the combinations of С677Т/А1298С genotypes had a significant 9,7-fold higher risk of NTDs (OR=9,75; p=0,018). Conclusion. There is significant association between С677Т and А1298С polymorphism in MTHFR gene and neural tube defects in the Kyrgyz population. An increased risk of neural tube defects associated with heterozygous A1298C genotype, 1298C allele and combinations of С677Т/А1298С in MTHFR gene.

Polymorphisms of Methylenetetrahydrofolate Reductase Gene and Risk of Ischemic Stroke in a Spanish Population.

Ischemic stroke (IS) is a multifactorial disease caused by the interaction of genetic and environmental factors. The question of whether mild hyperhomocysteiemia (Hcy) is a risk factor for CVD has been debated and is still unclear. Common single nucleotide polymorphisms (C677T and A1298C) in the methylenetetrahydrofolate reductase gene (MTHFR) decrease the activity of the enzyme, leading to hyperhomocysteinemia, particularly in folate-deficient states. We investigated whether there is a link between MTHFR gene C677T and A1298C polymorphisms or plasma homocysteine and IS. Patients and methods: Genotypic analyses were performed on 308 consecutive unrelated patients diagnosed with IS, 147 women and 161 men, mean age 700.8 years, who were diagnosed according to the Trial of Org 10172 in Acute Stroke Treatment. All included cases were age and sex matched to a control from the same geographic area who had no history of vascular disease. Patients and controls completed a questionnaires including blood pressure, diabetes status, total serum cholesterol level and smoking history. Genetic tests were performed by RFLP-PCR and homocysteine levels in plasma were measured by ELISA method. The strength of the association of the polymorphisms with the occurrence of IS was estimated by calculation of the OR and its 95%CI by exact method. P values less than 0.05 were considered significant. Logistic regression analysis was applied to estimate the risk in a multivariable predictive model with dependent variable (case/control) and all independent variables significant in the bivariate analysis. SPSS 9.0 was used for the statistical analysis. Results: The distribution of MTHFR gene C677T genotypes in patients (or controls) was: CC-genotype in 134 cases, 44.1% (155 controls, 50.5%); CT-genotype in 131 cases, 43.1% (138 controls, 44.9%); and TT-genotype in 39 cases, 12.8% (14 controls, 4.6%). The distribution of MTHFR gene A1298C genotypes in patients (or controls) was: AA-genotype in 164 cases, 55.6% (127 controls, 41.2%); AC-genotype in 113 cases, 38.3% (149 controls, 48.4%); and CC-genotype in 18 cases, 6.1% (32 controls, 10.4%). Genotype analysis showed a significant higher prevalence of the TT-genotype of MTHFR C677T in patients (p= 0.001;OR= 3.08;95%CI= 1.63–5.79). Nevertheless, genotype analysis showed a lower prevalence of the CC genotype of MTHFR A1298C in patients (p= 0.056;OR= 0.56;95%CI= 0.3–1.02). The genetic analysis was similar for the different subtypes of IS. Homocysteine plasma level was significantly higher in homozygosity for 677T allele than wild type (20.2±9.3 mmol/l and 17.4±6.5 mmol/l; p=0.029) and was lower in homozygosity for 1298C allele than wild type (16.2±5.7 mmol/l and 18.7±9.0 mmol/l; p=0.029). Homocysteine plasma levels in doubly heterozygous for C677T and A1298C mutations in the MTHFR gene were higher than the other genotypes (20.6±8.4 mmol/l and 18.6±8.3 mmol/l; p= 0.133). Logistic regression analysis showed a independent association of 677T allele of MTHFRwith CVD. Also hypertension, diabetes mellitus and current smoking status were statistically associated with CVD. Conclusions: Our findings suggest that the T allele of 677 MTHFR polymorphism is a genetic risk factor for IS in Spanish population. The unexpected protective effect of the 1298C allele of 1298 MTHFR polymorphism for IS needs further study. Supported by Grant FIS 03/0176. Oa R: Fundacion Conchita Rabago Grant. Santos AB: Fundacion LAIR 2004 Grant.