Association of a methylene tetrahydrofolate reductase C677T polymorphism with several blood chemical levels in a Chinese population

Susceptibility to hypertension based on MTHFR rs1801133 single nucleotide polymorphism and MTHFR promoter methylation

Background

The aetio-pathologenesis of hypertension is multifactorial, encompassing genetic, epigenetic, and environmental factors. The combined effect of genetic and epigenetic changes on hypertension is not known. We evaluated the independent and interactive association of MTHFR rs1801133 single nucleotide polymorphism (SNP) and MTHFR promoter methylation with hypertension among Taiwanese adults.

Methods

We retrieved data including, MTHFR promoter methylation, MTHFR rs1801133 genotypes (CC, CT, and TT), basic demography, personal lifestyle habits, and disease history of 1,238 individuals from the Taiwan Biobank (TWB).

Results

The distributions of hypertension and MTHFR promoter methylation quartiles (β < 0.1338, 0.1338 ≤ β < 0.1385, 0.1385 ≤ β < 0.1423, and β ≥ 0.1423 corresponding to

Conclusion

Independently, rs1801133 TT was associated with a higher risk of hypertension, but methylation was not. Based on genotypes, lower methylation was dose-dependently associated with a higher risk of hypertension in individuals with the CC genotype. Our findings suggest that MTHFR rs1801133 and MTHFR promoter methylation could jointly influence hypertension susceptibility.

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Key Words

• MTHFR
• hypertension
• interaction
• promoter methylation
• rs1801133
• susceptibility

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MESH Headings Collapse

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Affiliation(s)

Ming-Huang Chiu Department of Pulmonology and Respiratory Care, Cathay General Hospital, Taipei City, Taiwan
Chia-Hsiu Chang Cardiovascular Center, Cathay General Hospital, Taipei City, Taiwan
Disline Manli Tantoh Department of Medical Imaging, Chung Shan Medical University Hospital, Taichung City, Taiwan Department of Public Health and Institute of Public Health, Chung Shan Medical University, Taichung City, Taiwan
Tsui-Wen Hsu Superintendent Office, Institute of Medicine, Cathay General Hospital, Taipei City, Taiwan
Chih-Hsuan Hsiao Department of Public Health and Institute of Public Health, Chung Shan Medical University, Taichung City, Taiwan
Ji-Han Zhong Department of Public Health and Institute of Public Health, Chung Shan Medical University, Taichung City, Taiwan
Yung-Po Liaw Department of Medical Imaging, Chung Shan Medical University Hospital, Taichung City, Taiwan Department of Public Health and Institute of Public Health, Chung Shan Medical University, Taichung City, Taiwan Institute of Medicine, Chung Shan Medical University, Taichung City, Taiwan

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APOE Genetic Polymorphism rs7412 T/T Genotype May Be a Risk Factor for Essential Hypertension among Hakka People in Southern China

Objective

One of the causes of hypertension is a genetic factor. The purpose of this study was to look at the relationship between apolipoprotein E (APOE) and methylenetetrahydrofolate reductase (MTHFR) polymorphisms and essential hypertension in the Hakka population.

Methods

The study included 2,850 patients with hypertension and 2,034 controls. APOE rs429358, rs7412, and MTHFR rs1801133 were genotyped by polymerase chain reaction (PCR)-microarray. The differences in these polymorphisms between the two groups were analyzed.

Results

The genotype and allele frequency of APOE and MTHFR polymorphisms did not differ significantly between hypertensive patients and controls. Patients with hypertension who were APOE rs429358C/C homozygous had higher TG, TC, LDL-C, and Apo-B levels, whereas patients with the T/T genotype had higher HDL-C levels. Patients with hypertension who were APOE rs7412T/T homozygous had higher TG and TC levels and lower LDL-C and Apo-B levels. Homocysteine (Hcy) levels in patients with MTHFR CC, CT, and TT genotypes were increased, while patients with the TT genotype and T allele had higher Hcy levels than those of patients with other genotypes and the C allele. The APOE rs7412T/T genotype in the co-dominant model (APOE rs7412T/T vs. C/C) (gender-, age-, smoking-, and drinking-adjusted OR 2.682, 95% CI, 1.072–6.710, P=0.035) was a significant risk factor for hypertension. The APOE rs429358 and MTHFR rs1801133 genotypes in co-dominant, dominant, and recessive models were not significant risk factors for hypertension.

Conclusions

It supports that APOE polymorphisms are related to hypertension in the Hakka population. Specifically, the APOE rs7412T/T genotype may be a risk factor for hypertension.

Associations of Two Common Polymorphisms in MTHFR Gene with Blood Lipids and Therapeutic Efficacy of Simvastatin

BACKGROUND AND PURPOSE

Cardio-cerebrovascular disease is an important public health challenge worldwide, and its complex etiology has not been elucidated fully. The study was to investigate the relationship between two common polymorphisms C677T and A1298C in the methylenetetrahydrofolate reductase (MTHFR) gene, baseline lipids and the lipid-lowering efficacy of simvastatin in a Chinese hyperlipidemic population.

METHODS

All participants were recruited from Anhui, China. By the extreme sampling method, we selected subjects with low response (n=108) and high response (n=106) based on their adjusted lipid-lowering response to simvastatin administrated for 8 consecutive weeks. Both MTHFR C677T and A1298C loci were genotyped by MALDI-TOF MS platform. Serum triglyceride (TG), total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), and high-density lipoprotein cholesterol (HDL-C) levels were measured at baseline and after 8 weeks of oral 20 mg/d tablet of simvastatin.

RESULTS

Patients with the 677TT genotype had significantly higher baseline TC, HDL-C, and change in HDL-C (ΔHDL-C) levels after treatment than those with 677CC+CT genotypes (β = 0.207, P = 0.045; β = 0.182, P = 0.026; and β = 0.16, P = 0.002, respectively). Patients with 1298AC+CC genotypes had significantly higher baseline LDL-C and change in LDL-C (ΔLDL-C) levels (β = 0.276, P =0.043; β = 0.359, P = 0.025, respectively) than those with 1298AA genotype. We found statistical interactions between the two SNPs in association with baseline HDL-C (P for interaction = 0.034), TC (P for interaction = 0.069), and TG (P for interaction = 0.034). Baseline TC (P = 0.027) and HDL-C (P = 0.046) and change in HDL-C (P = 0.019) were different among those with the MTHFR A-T haplotype compared with A-C.

CONCLUSIONS

Our major findings suggest that both MTHFR C677T and A1298C polymorphisms could be important genetic determinants of lipid traits and drug efficacy of simvastatin. This will contribute to a better understanding of strategies for personalized medication in Chinese patients with dyslipidemia.

Methylenetetrahydrofolate Reductase Polymorphism (rs1801133) and the Risk of Hypertension among African Populations: A Narrative Synthesis of Literature

In this review, we have gathered and analyzed the available genetic evidence on the association between the methylenetetrahydrofolate reductase gene (MTHFR), rs1801133 and the risk of Hypertension (HTN) in African populations, which was further compared to the global data evidence. This review was reported following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) protocol and Human Genome Epidemiology Network (HuGENet) guidelines. Literature was retrieved through major search databases, including PubMed, Scopus, Web of Science, and African Journal Online. We identified 64 potential studies, of which 4 studies were from the African continent and 60 studies were reported globally. Among the studies conducted in Africa, only two (n = 2) reported a significant association between the MTHFR (rs1801133) and the risk of developing HTN. Only one (n = 1) study population was purely composed of black Africans, while others were of other ethnicities. Among studies conducted in other continents (n = 60), forty-seven (n = 47) studies reported a positive association between MTHFR (rs1801133) and the risk of developing HTN, whereas the remaining studies (n = 14) did not show a significant association. Available literature suggests an apparent association between rs1801133 and HTN in global regions; however, such information is still scarce in Africa, especially in the black African population.

Association of ALDH2 rs671 and MTHFR rs1801133 polymorphisms with hypertension among Hakka people in Southern China

Background

Genetic factors play an important role in susceptibility to hypertension. Herein, the association between acetaldehyde dehydrogenase 2 (ALDH2) and methylenetetrahydrofolate reductase (MTHFR) gene polymorphisms and hypertension was analyzed among Hakka population in southern China.

Methods

A total of 3057 hypertensive patients and 2215 controls were enrolled. The ALDH2 rs671 and MTHFR rs1801133 genotyping were analyzed using gene chip. Relevant information and medical records of these subjects were collected.

Results

Hypertensive patients with ALDH2 rs671 G/A heterozygous had lower systolic blood pressure (SBP) than other genotypes (P < 0.001), while hypertensive patients with A allele had lower diastolic blood pressure (DBP) than patients with G allele (P < 0.001). The level of plasma homocysteine (Hcy) in patients with MTHFR CC, CT and TT genotypes showed an increasing trend (P < 0.001). The ALDH2 G/A genotype in the co-dominant model (adjusted OR 1.251, 95% CI 1.024–1.528, P = 0.028) and ALDH2 A/A genotype in the recessive model (adjusted OR 1.221, 95% CI 1.008–1.478, P = 0.041) were significant risk factors for the presence of hypertension. The MTHFR C/T genotype in the co-dominant model (adjusted OR 1.307, 95% CI 1.039–1.643, P = 0.022) and MTHFR C/T and T/T genotypes in the dominant model (adjusted OR 1.281, 95% CI 1.146–1.430, P < 0.001) were significant risk factors for the presence of hypertension. Further, logistic regression analysis showed that age, smoking, alcohol consumption, hyperhomocysteinemia, and high level of serum TG, Apo-A1, Apo-B were significant risks for hypertension.

Conclusions

In summary, ALDH2 rs671 G/A, A/A genotypes and MTHFR rs1801133 C/T, T/T genotypes may be risk factors for hypertension in this Chinese Hakka population.

Association Between MTHFR Polymorphisms and the Risk of Essential Hypertension: An Updated Meta-analysis

BACKGROUND

Since the 1990s, there have been a lot of research on single-nucleotide polymorphism (SNP) and different diseases, including many studies on 5,10-methylenetetrahydrofolate reductase (MTHFR) polymorphism and essential hypertension (EH). Nevertheless, their conclusions were controversial. So far, six previous meta-analyses discussed the internal relationship between the MTHFR polymorphism and EH, respectively. However, they did not evaluate the credibility of the positive associations. To build on previous meta-analyses, we updated the literature by including previously included papers as well as nine new articles, improved the inclusion criteria by also considering the quality of the papers, and applied new statistical techniques to assess the observed associations.

OBJECTIVES

This study aims to explore the degree of risk correlation between two MTHFR polymorphisms and EH.

METHODS

PubMed, EMBASE, the Cochrane Library, CNKI, and Wan Fang electronic databases were searched to identify relevant studies. We evaluated the relation between the MTHFR C677T (rs1801133) and A1298C (rs1801131) polymorphisms and EH by calculating the odds ratios (OR) as well as 95% confidence intervals (CI). Here we used subgroup analysis, sensitivity analysis, cumulative meta-analysis, assessment of publication bias, meta-regression meta, False-positive report probability (FPRP), Bayesian false discovery probability (BFDP), and Venice criterion.

RESULTS

Overall, harboring the variant of MTHFR C677T was associated with an increased risk of EH in the overall populations, East Asians, Southeast Asians, South Asians, Caucasians/Europeans, and Africans. After the sensitivity analysis, positive results were found only in the overall population (TT vs. CC: OR = 1.14, 95% CI: 1.00-1.30, P _h = 0.032, I ² = 39.8%; TT + TC vs. CC: OR = 1.15, 95% CI: 1.01-1.29, P _h = 0.040, I ² = 38.1%; T vs. C: OR = 1.14, 95% CI: 1.04-1.25, P _h = 0.005, I ² = 50.2%) and Asian population (TC vs. CC: OR = 1.14, 95% CI: 1.01-1.28, P _h = 0.265, I ² = 16.8%; TT + TC vs. CC: OR = 1.17, 95% CI: 1.04-1.30, P _h = 0.105, I ² = 32.9%; T vs. C: OR = 1.10, 95% CI: 1.02-1.19, P _h = 0.018, I ² = 48.6%). However, after further statistical assessment by FPRP, BFDP, and Venice criteria, the positive associations reported here could be deemed to be false-positives and present only weak evidence for a causal relationship. In addition, when we performed pooled analysis and sensitivity analysis on MTHFR A1298C; all the results were negative.

CONCLUSION

The positive relationships between MTHFR C677T and A1298C polymorphisms with the susceptibility to present with hypertension were not robust enough to withstand statistical interrogation by FPRP, BFDP, and Venice criteria. Therefore, these SNPs are probably not important in EH etiology.

Evidence on the causal link between homocysteine and hypertension from a meta-analysis of 40 173 individuals implementing Mendelian randomization

Numerous researchers have investigated the associations among methylenetetrahydrofolate reductase gene (MTHFR) C677T polymorphism, homocysteine (Hcy) concentration, and hypertension. However, the results are controversial. Thus, a meta-analysis implementing Mendelian randomization approach was conducted to examine the hypothesis that elevated Hcy concentration plausibly contributes to increased risk of hypertension. Based on several inclusion and exclusion criteria, eligible studies were selected to explore the correlation between MTHFR C677T and hypertension risk, MTHFR C677T and Hcy concentration in hypertension, and Hcy concentration and hypertension, and they were evaluated by odds ratios (ORs), effect size (ES), and standard mean difference with their corresponding 95% confidence intervals (95% CIs), respectively. Moreover, Mendelian randomization was implemented to evaluate the relationship between Hcy and hypertension. Consequently, 14 378 cases and 25 795 controls were involved in this study and the results showed that MTHFR C677T led to an elevated risk of hypertension (for T vs C: OR = 1.27, 95% CI = 1.17-1.37; for TT vs CC: OR = 1.53, 95% CI = 1.30-1.79). Additionally, in hypertensive subjects, the pooled Hcy concentration in individuals of TT genotype was 7.74 μmol/L (95% CI: 5.25-10.23) greater than that in individuals of CC genotype. Moreover, the pooled Hcy concentration in hypertensive was 0.69 μmol/L (95% CI: 0.50-0.87) greater than that in controls. The estimated causal OR associated with hypertension was 1.32 for 5 μmol/L Hcy increment. Via MTHFR C677T polymorphism, the findings in the present study demonstrated that there exists evidence on causal link between Hcy concentration and the risk of hypertension.

Association of the MTHFR 677C>T Polymorphism with Obesity and Biochemical Variables in a Young Population of Mexico

BACKGROUND

Methylenetetrahydrofolate reductase (MTHFR) gene polymorphisms have been associated with overweight people and obesity. The goal of this study was to investigate the relationship of the MTHFR 677C>T polymorphism with obesity and biochemical variables in young individuals of Mexico.

METHODS

A total of 316 young individuals were included in the study, 172 with normal weight (NW) and 144 with over weight/obesity. Body mass index (BMI) was classified as NW, overweight, and obesity. Also, waist circumference was measured. Moreover, glucose, total cholesterol, and triglycerides were determined. Genotyping for MTHFR 677C>T polymorphism was performed by the PCR-RFLP method.

RESULTS

There was no difference in the distribution of the MTHFR 677C>T polymorphism between individuals with NW and overweight/obesity; neither when they were divided by overweight vs NW, nor when we contrasted obese vs NW. However, an analysis stratified by gender showed a significant protector effect of the TT genotype against obesity in males and elevated waist circumference in females. Also, overweight/obese individuals with TT genotype had less risk of high cholesterol or triglycerides than overweight/obese subjects with the other genotypes.

CONCLUSIONS

These results suggest that the MTHFR 677T polymorphism might not be a risk factor for being overweight/obesity. Rather, on the basis of our results, this variant could be a protector effect. However, further large-scale population-based studies are still necessary to clarify the role of the MTHFR 677C>T polymorphism in overweight, obesity, and lipid profile level.

Interactions between genetic variants involved in the folate metabolic pathway and serum lipid, homocysteine levels on the risk of recurrent spontaneous abortion

Background

The interaction between folate pathway gene polymorphisms and homocysteine, serum lipid leverls are poorly understood in patients with recurrent spontaneous abortion (RSA). The aim of this study is to explore the effects of folate pathway gene polymorphisms (the 5–10-methylenetetrahydrofolate reductase, MTHTR C677T, MTHFR A1298C and the methionine synthase reductase, MTRR A66G) and their interactions with homocysteine on serum lipid levels in patients with RSA.

Methods

A total of 403 RSA women and 342 healthy women were randomly selected. Genotyping of the MTHFR C677T, A1298C and MTRR A66G were performed by TaqMan-MGB technique. Serum homocysteine, folate, fasting glucose, fasting insulin, Interleukin 6, Tumor necrosis factorα (TNFα) and lipid profiles were measured according to the kits. Continuous variables were analyzed using 2-sample t-tests. Categorical variables were analyzed and compared by χ² or Fisher’s exact tests. Unconditional logistic regression model was applied to test the interactions of gene polymorphisms on RSA.

Results

The distribution of genotype of CC, CT TT and T allele of MTHFR C677T, genotype of AA and C allele of MTHFR A1298C, and genotype of AA, AG and G allele of MTRR A66G were different between cases and controls (all p were < 0.05). There were significant interactions between MTHFR C677T-A1298C and MTHFR A1298C-MTRR A66G in RSA group and control group, with ORs of 1.62 (95%CI: 1.28–2.04, p < 0.001) and 1.55 (95%CI: 1.27–1.88, p < 0.001), respectively. Serum TNFα level and insulin resistant status (HOMR-IR) were higher in RSA group than in control group (p = 0.038, 0.001, respectively). All the three gene SNPs except MTRR 66AG gene variant had detrimental effects on HOMA-IR (all p were < 0.05). RSA group who carried the MTHFR 677CT, TT, CT/TT genotypes and MTRR 66AG, AG/GG genotypes had detrimental effects on serum homocysteine levels, the MTHFR 677CT, CT/TT genotype carriers had favorable effects on serum folate levels, the MTHFR 677TT, CT/TT, 1298 AC, AC/CC genotype carriers had detrimental effects on serum low-density lipoprotein cholesterol (LDL-C) levels, and the MTRR 66AG genotype carriers had lower high-density lipoprotein cholesterol (HDL-C) levels than the AA genotype carriers (all p were < 0.05).

Conclusions

Interaction between the MTHFR C677T, A1298C and MTHFR A1298C, MTRR A66G are observed in our RSA group. Besides, all the three gene SNPs except MTRR 66AG gene variant had detrimental effects on HOMA-IR. MTHFR C677T and MTRR A66G gene variants had detrimental effects on serum homocysteine levels and insulin resistance status, while MTHFR C677T, A1298C and MTRR A66G gene variants had detrimental effects on certain serum lipid profiles.

Investigation of potential biomarkers for thrombosis related diseases in Turkish Cypriot population

Genetic and environmental factors are involved in development of many diseases. The allelic frequencies may differ in different populations and in different ethnic groups. The aim of this study was to investigate the genotypes of MTHFR and factor VII polymorphisms and to identify biomarkers for thrombosis related diseases in Turkish Cypriot population. The lipid profiles and genotypes of MTHFR polymorphisms (rs1801133, rs1801131) and factor VII (rs6046) genes were investigated for the first time in the Turkish Cypriot population. The heterozygosity for MTHFR (rs1801133, rs1801131) and FVII (rs6046) polymorphisms is high in Turkish Cypriot population. The heterozygosity for MTHFR C677T was 38%, MTHFR A1298C was 40% and factor VII G353A was 37%, respectively. Allelic frequencies between males and females were similar. There were no correlations between the genotypes of polymorphisms and the lipid profiles. This study is the first genetic epidemiology study that investigated the allelic frequencies of MTHFR and FVII polymorphisms associated with metabolic syndromes. This study proves to be a crucial analysis in order to use these polymorphisms as a predictor of disease development in the Turkish Cypriot community.

Relationship between lifestyle factors and hyperhomocysteinemia in general Chinese population: a cross-sectional study

OBJECTIVES

Hyperhomocysteinemia (Hhcy) is a known cardiovascular disease (CVD) risk factor. Observational studies had supported the role of lifestyle factors such as physical activity, diet and alcohol consumption in CVD prevention. Our study aimed to determine the relationship between Hhcy and lifestyle factors in general Chinese population.

METHODS

In this cross-sectional study, a total of 7135 adults (3320 men and 3815 women) aged 35 years or older were recruited from the rural Northeast China. Data on lifestyle factors, such as physical activities, sleep duration, current smoking and drinking status, dietary habits and familial factors were collected in interviews and laboratory examinations were performed by well-trained personnel.

RESULTS

Plasma total homocysteine (tHcy) level was higher in men than in women, and greater in the elderly than in other age groups. Subjects with Hhcy were more likely to be current smokers (men: OR 1.328, 95% CI 1.143-1.543, p<0.001; women: OR 1.465, 95% CI 1.214-1.767, p<0.001). Separately, men with Hhcy were more likely to have an education of primary school or below (OR 1.251, 95% CI 1.068-1.465, p=0.006) and less likely to eat more vegetables (OR 0.927, 95% CI 0.863-0.996, p=0.037) than the normal-tHcy participants. In women, participants with Hhcy were more likely to have longer sleeping time (>9h/d) (OR 1.677, 95% CI 1.292-2.177, p<0.001), low physical activity (OR 1.721, 95% CI 1.197-2.475, p=0.044) and increased diet score (OR 1.126, 95% CI 1.007-1.259, p=0.037) and less likely to be current drinkers (OR 0.488, 95% CI 0.297-0.802, p=0.005) than the normal-tHcy participants.

CONCLUSION

Our study revealed that physical activity and current drinking status were not significantly associated with Hhcy in males, but inversely associated in females. In both genders, current smoking status and dietary habits were significantly associated with Hhcy. Our study supports existing recommendations for Chinese to maintain a physically active behaviors and healthy lifestyle habits.

Gender-specific interactions of MTHFR C677T and MTRR A66G polymorphisms with overweight/obesity on serum lipid levels in a Chinese Han population

Background

Little is known regarding the interactions of methylenetetrahydrofolate reductase (MTHFR) C677T and methionine synthase reductase (MTRR) A66G polymorphisms with overweight/obesity on serum lipid profiles. The aim of the current study was to explore interactions between the two polymorphisms and overweight/obesity on four common lipid levels in a Chinese Han population and further to evaluate whether these interactions exhibit gender-specificity.

Methods

A total of 2239 participants (750 females and 1489 males) were enrolled into this study. The genotypes of the MTHFR C677T and MTRR A66G were determined by a TaqMan assay. Overweight and obesity were defined as a body mass index between 24 and 27.99 and ≥ 28 kg/m², respectively. The interactions were examined by factorial design covariance analysis, and further multiple comparisons were conducted by Bonferroni correction.

Results

There was no significant difference in the genotypic and allelic frequencies between females and males (MTHFR 677 T allele: 54.47 % for females and 54.40 % for males; MTRR 66G allele: 24.73 % for females and 24.71 % for males). Interaction between the MTHFR C677T polymorphism and overweight/obesity on serum triglyceride levels, and interaction between the MTRR A66G polymorphism and overweight/obesity on serum high-density lipoprotein cholesterol levels were detected in women (P = 0.015 and P = 0.056, respectively). For female subjects with overweight/obesity, the serum triglyceride levels in MTHFR 677TT genotype [1.09 (0.78–1.50) mmol/L] were significantly higher as compared with MTHFR 677CC genotype [0.90 (0.60–1.15) mmol/L, P = 0.007], and the MTRR 66GG genotype carriers had higher serum high-density lipoprotein cholesterol levels than those with MTRR 66AG genotype (1.46 ± 0.50 vs. 1.19 ± 0.31 mmol/L, P = 0.058). Furthermore, in male subjects with overweight/obesity, the MTHFR 677CT genotype carriers had higher low-density lipoprotein cholesterol levels than those with MTHFR 677TT genotype (2.96 ± 1.07 vs. 2.74 ± 0.88 mmol/L, P = 0.015).

Conclusions

Our results indicate that there exist interactive effects of the MTHFR C677T and MTRR A66G polymorphisms with overweight/obesity on some lipid traits in Chinese Han population, and the effects were gender-specific.

The T Allele of MTHFR c.C677T and Its Synergism with G (Val 158) Allele of COMT c.G472A Polymorphism Are Associated with the Risk of Bipolar I Disorder

AIMS

The aims of the present study were to investigate the association between methylenetetrahydrofolate reductase (MTHFR) c.C677T (p.A222V) and catechol-O-methyltransferase (COMT) c.G472A (p.V158M) polymorphisms and their synergism with respect to bipolar I disorder (BID).

METHODS

Within an ethnic Kurdish population from Western Iran the MTHFR c.C677T and COMT c.G472A polymorphisms were studied in 150 patients with BID and 149 gender- and age-matched healthy individuals using the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method.

RESULTS

In the presence of MTHFR 677T allele and MTHFR TT genotype, the risk of BID was 1.44 times (p = 0.046) and 1.81-fold (p = 0.029), respectively. The frequency of COMT 472G allele compared to the A allele in cases and controls was not significant (p = 0.078); however there was a synergism between the presence of MTHFR 677T and COMT 472G alleles that increased the risk of BID by 2.58-fold (p = 0.003).

CONCLUSIONS

Our findings indicate that the presence of the lower activity allele of MTHFR (677T) increased the risk of BID. In addition, the concomitant presence of the MTHFR 677T allele with the COMT 472G allele was associated with increased susceptibility to BID in our population.