Correlation Between the MTHFR C677T Genotype and Coronary Heart Disease in Populations from Gansu,China

Abstract

This study was designed to evaluate the relationship between polymorphisms in the methylenetetrahydrofolate reductase (MTHFR) gene and coronary heart disease (CHD) in populations from the Gansu region of China. The MTHFR C677T polymorphism genotypes from 209 patients with CHD, as confirmed by coronary angiography, and 212 non-CHD control patients were identified using PCR gold magnetic particle chromatography. We simultaneously evaluated homocysteine (Hcy) and folate levels in these samples using biochemical methods. The TT genotype of the MTHFR C677T locus was significantly more frequent in the CHD group than in the control, while the CC genotype was significantly less frequent in CHD patients than in non-CHD patients (p < 0.05). In addition, biochemical analysis revealed that the serum Hcy levels increased, and folate levels decreased in the TT genotype. Logistic regression analysis showed that this correlation was independent of nationality, sex, age, body mass index, medical history, and blood lipid level (p < 0.05). The occurrence of the TT genotype at the MTHFR C677T locus was closely associated with CHD in the Gansu population and may serve as a biomarker of increased risk for this disease.

Introduction

Coronary heart disease (CHD) is a complex disorder involving various risk factors (Hou et al, 2020). With associated mortality increasing every year (Musunuru and Kathiresan, 2019), CHD has emerged as the largest cause of death due to human cardiovascular disease globally. A family history of CHD can significantly increase the probability of CHD, suggesting that its incidence may have some genetic basis (Benincasa et al, 2019). Clarifying the specific impact of various gene polymorphisms can help to make disease prevention and treatment more accurate.

Methylenetetrahydrofolate reductase (MTHFR) is a key enzyme in the metabolism of both folate and homocysteine (Hcy), which (Stajnko et al, 2019) when mutated, can reduce the remethylation of Hcy and can lead to its accumulation in the body (Liang et al, 2019). High Hcy levels in the body are an independent risk factor for many diseases, including CHD (Zaghloul et al, 2019).

Many single-nucleotide polymorphisms exist in the MTHFR gene, with C677T being the most clinically significant (Bhargava et al, 2012; Botto and Yang, 2000). Prior research has demonstrated that the frequencies of C677T vary markedly across different regions and ethnic groups worldwide, and even show a geographical gradient in some regions, such as Europe, North America, and India (Bhargava et al, 2012). Significant differences in the genotypic distribution of the MTHFR gene locus 677 in different ethnic groups and regions have also been reported in China (Zhao et al, 2018), and a clear geographical trend was also reported (Yang et al, 2017). However, these results were irreproducible and inconclusive. Accurate information on the distribution of this polymorphism will be beneficial for gene-disease association studies and population genetics as well as for the prevention of various diseases and health impact assessment (Wilcken et al, 2003).

Most studies on CHD and MTHFR gene polymorphisms in China are concentrated in South China, and the genotype distribution characteristics of the MTHFR gene locus 677 and its correlation with CHD in the Gansu region have not been reported. This study investigated the relationship between MTHFR C677T gene mutations and the serum Hcy and folate levels in the Gansu population to provide novel insights into the development of better prevention and treatment programs for CHD in this region of China.

Methods

Ethics statement

Informed consent was obtained from all subjects before participating in this study. Ethics approval for the study was granted by the Second Hospital of Lanzhou University Ethics Committee and the institutional approval number for this study is 2021A-246.

Sample size estimation

According to literature (Chi et al, 2020; Li et al, 2019), the frequency of TT genotype of MTHFR C677T locus in the northern Chinese population was 26.7%, with odds ratio (OR) = 2.068 for CHD. The sample size was determined to be 176 by using the PASS software, which means that at least 176 cases in the CHD group and 176 cases in the control group were required for accurate statistical analysis.

Patient population

From January 2020 to December 2021, a total of 421 cases were selected from our cardiology inpatients, outpatients and physical examination patients (Supplementary Data). The inclusion criteria for the CHD group were a clear diagnosis of CHD and informed consent was obtained from each patient for the relevant examinations described in this study.

Our exclusion criteria included congenital heart disease, cardiomyopathy, myocarditis, cerebral infarction, cerebral hemorrhage, malignant tumor, blood disease, immune system disease, respiratory failure, heart failure, and other important organ dysfunctions; contraindications for coronary angiography; recent surgery; trauma; and serious infection. This left a total of 209 patients (134 men and 75 women) who were diagnosed with CHD using coronary angiography with an average age of 60.27 ± 10.37 years, and 212 non-CHD controls (113 men and 99 women), with an average age of 61.09 ± 10.45 years.

These patients were interviewed by two doctors, and their data, sex, age, ethnicity, history of hypertension, diabetes, and body mass index were recorded. Approval was obtained from the Ethics Committee of the Second Hospital of Lanzhou University. The procedures used in this study adhere to the tenets of the Declaration of Helsinki. All of the subjects were provided the study protocol at the time of recruitment and informed written consent was obtained.

Coronary artery disease diagnosis and coronary artery stenosis degree score

All patients underwent coronary angiography, and the results were evaluated by two experienced cardiovascular interventional physicians. Patients were diagnosed with CHD when the degree of lumen stenosis of at least one coronary artery was >50%, while non-CHD samples were identified when the degree of stenosis was <50%. All patients in the CHD group were evaluated using the syntax scoring system proposed by the European Heart Association, and the results were posted on the SYNTAX Score website (www.syntaxscore.com) (Ong et al, 2006). These scores were calculated via the independent evaluation of the coronary angiography results by two senior cardiovascular interventional physicians. Conflicting scores were resolved by obtaining input from a third physician.

Serum triglyceride, cholesterol, high-density lipoprotein, low-density lipoprotein, Hcy, and folate levels

We collected 2 mL of fasting median elbow venous blood from each patient on the second day after admission. These samples were centrifuged at 4000 rpm for 20 minutes to separate the serum, then stored at −20°C until further analysis. The serum samples were thawed at 37°C and their triglyceride (TG), cholesterol (TC), high-density lipoprotein (HDL), and low-density lipoprotein (LDL) levels were detected using a Cobas800 automatic biochemical analyzer (Roche, Basel, Swiss).

The serum samples were also assayed for Hcy using the Hcy detection kit (Leadman, Beijing, China) and folate levels using Folate detection kit (Roche Diagnostic Company, Shanghai, China) in a Cobas800 automatic biochemical analyzer (Roche).

Whole blood DNA extraction

A second 3 mL sample of fasting elbow median venous blood was collected into an EDTA-k2 anticoagulant tube from each patient on the second day after admission. We then extracted genomic DNA from 200 μL of each of these samples using a human whole blood genomic DNA extraction kit (Tiangen, Beijing, China). The concentration (50–200 ng/μL) and purity of the extracted DNA were evaluated by a Multiskan GO nucleic acid analyzer (Thermo Scientific, MA). Samples with an A260/A280 ratio between 1.8 and 2.0 were used for subsequent experiments; these samples were stored at −20°C until use.

MTHFR genotype determination

PCR amplification of the MTHFR C677T gene targets was performed using T100™ Thermal Cycler (Bio, CA) and a PCR gold magnetic particle (Xi'an Gold Magnetic Nanobiotechnology, Xi'an, China) according to the manufacturers' instructions.

Statistical analysis

Statistical analysis was performed using SPSS 23.0. The representativeness of the control and CHD groups was evaluated using the Hardy–Weinberg balance test (p < 0.05). Discrete variables were described as percentages and compared using the χ ² test. Continuous variables were described as the means ± standard deviations and compared using t-test and single-factor analysis (independent variables) or Kruskal–Wallis test (nonparametric data). The CHD incidence rate was evaluated using two logistic regression analyses, and both the OR and the 95% confidence interval values were considered. All statistical tests were applied as bilateral probability tests, and the differences were considered statistically significant at p < 0.05.

Results

Comparison of demographic data of CHD and non-CHD cohorts

We collected data from a total of 421 patients. Statistical analysis revealed a significant difference in the sex ratio of these cohorts, with more men in the CHD group (p < 0.05). There were no significant differences in age, body mass index, ethnicity, or complications between these two groups (p > 0.05; Table 1).

Table 1.

Comparison of the Demographic Data for Coronary Heart Disease (CHD) and Non-CHD Cohorts

	Groups		Statistics χ ²	p
	Non-CHD	CHD	Statistics χ ²	p
Sex
Male	113	134	5.075	0.024
Female	99	75	5.075	0.024
Complication
No complications	116	101	5.546	0.136
Hypertension	49	50
Diabetes	22	17
Hypertension+diabetes	25	41
Ethnicity
Han	155	156	0.113	0.945
Hui	37	36
Tibetan	20	18
Age	61.50 (16)^a	62.00 (16)^a	−0.80	0.424
BMI	24.44 ± 3.16	24.77 ± 3.34	−1.023	0.307

Nonparametric test expressed as P50 (P25).

BMI, body mass index; CHD, coronary heart disease.

Comparison of serum indexes between CHD and non-CHD groups

We detected significantly higher Hcy and TG levels and lower folate and HDL levels in the CHD group (p < 0.05) than in the control group. No differences in TC and LDL levels were detected between these two groups (p > 0.05; Table 2).

Table 2.

Comparison of Serum Indexes Between Coronary Heart Disease (CHD) and Non-CHD Patient Groups

	Groups		Statistics t, t′, or Z	p
	Non-CHD	CHD	Statistics t, t′, or Z	p
Folate (ng/mL)	8.17 ± 3.35	6.75 ± 2.72	4.76	<0.001
Hcy (umol/L)	12.22 ± 4.35	17.59 ± 7.03	−9.398	<0.001
TC (mmol/L)	3.78 ± 0.98	3.81 ± 1.48	−0.26	0.795
TG (mmol/L)	3.05 ± 1.06	3.46 ± 1.31	−3.51	0.001
HDL (mmol/L)	1.16 (0.43)^a	1.03 (0.34)^a	−3.302	0.001
LDL (mmol/L)	2.52 (1.10)^a	2.40 (1.32)^a	−0.14	0.889

Nonparametric test expressed as P50 (P25).

Hcy, homocysteine; HDL, high-density lipoprotein; LDL, low-density lipoprotein; TC, cholesterol; TG, triglyceride.

MTHFR C677T genotype distribution

We evaluated the distribution and identity of the common MTHFR C677T locus genotypes within the non-CHD and CHD groups, for identifying patients with the TT, CT, and CC polymorphisms. The MTHFR C677T locus polymorphism evaluations for the non-CHD and CHD groups were both shown to be in Hardy–Weinberg equilibrium (Table 3), suggesting that these samples were representative of a broader population. These evaluations also revealed that the TT genotype was significantly more common in the CHD group than in the control group, while the CC genotype was significantly less common in the CHD group. In addition, C and T allele frequencies were significantly higher in the CHD group than in the non-CHD group (p < 0.05; Table 4).

Table 3.

Hardy-Weinberg Equilibrium Test

Group	Genotype			Statistics χ ²	p
Group	CC	CT	TT	Statistics χ ²	p
CHD group (n = 209)
Actual frequency	70	88	51	4.64	0.098
Theoretical frequency	62.1	104.6	44	4.64	0.098
Non-CHD group (n = 212)
Actual frequency	86	109	17	4.732	0.093
Theoretical frequency	92.4	95.2	24.5	4.732	0.093

Table 4.

Comparison of Methylenetetrahydrofolate Reductase C677t Genotype Distribution and Allele Frequencies in Coronary Heart Disease (CHD) and Non-CHD Samples

Genotypes	Groups		Statistics χ ²	p
Genotypes	Non-CHD	CHD	Statistics χ ²	p
CC	86	70	21.656	<0.001
CT	109	88
TT	17	51
C	281	228	11.625	0.001
T	143	190	11.625	0.001

Comparison of coronary syntax scores among different MTHFR C677T genotypes

Syntax evaluations of the CHD group revealed that the average score for the CC, CT, and TT types were 12.9 ± 5.90, 13.26 ± 6.37, and 15.3 ± 5.71, respectively. There were no significant differences between the three groups (H = 2.627, p = 0.075).

Comparison of serum Hcy and folate levels between different MTHFR C677T genotypes

Comparison of the blood Hcy and folate levels from each of the different genotypes revealed that the blood Hcy levels of patients with CT or TT genotype were significantly higher than those of patients with a CC genotype (p < 0.05), while folate levels were significantly decreased (p < 0.05). Further comparisons between these two groups revealed significant differences in Hcy and folate levels between CC versus CT and CC versus TT groups (p < 0.05), but not between CT versus TT groups (p > 0.05; Table 5).

Table 5.

Differences in the Serum Homocysteine and Folate Levels Between Different Methylenetetrahydrofolate Reductase C677T Genotypes

	Genotype			H-value	p
	CC	CT	TT	H-value	p
Hcy (umol/L)	11.2 (10.2)^a	14.6 (7.5)^a,b	15.6 (10.5)^a,b	14.832	0.001
Folate (ng/mL)	8.04 (4.63)^a	7.26 (4.45)^a,b	6.32 (4.8)^a,b	12.530	0.002

Nonparametric test, expressed as P50 (P25).

Compared with CC type.

Multivariate logistic analysis

We then performed a logistic regression analysis using CHD as the dependent variable, sex and MTHFR C677T genotype as the classification variables, and Hcy, folate, TC, TG, HDL, and LDL levels as the quantitative variables. This analysis showed that the TT genotype had a statistically significant impact on serum Hcy and folate levels, while the MTHFR C677T classification had a statistically significant impact on the incidence of CHD (p < 0.05). These evaluations also identified the TT genotype, serum Hcy, and MTHFR C677T classification as independent risk factors for CHD and folate as a protective factor against this disease (Table 6).

Table 6.

Results of Logistic Regression Analysis

	Regression coefficient	Standard error of regression coefficient	Wald chi-square	OR value	p	95% CI
Folate	−0.137	0.038	12.839	0.871	<0.001	0.808–0.939
Hcy	0.163	0.022	53.715	1.178	<0.001	1.127–1.230
Genotype			11.412		0.003
CT	0.633	0.361	3.083	1.883	0.079	1.675–3.025
TT	1.123	0.346	10.519	3.074	0.001	1.546–6.066
Constant	−2.78	1.113	6.267	0.062	0.012

CI, confidence interval; OR, odds ratio.

Discussion

CHD is a complex disorder affected by both polygenic inheritance and various environmental factors (McPherson and Tybjaerg-Hansen, 2016; Vinkhuyzen et al, 2013). Given its increasing incidence, we must strengthen our interventions designed to help prevent and treat these diseases (The Writing Committee of the Report on Cardiovascular Health and Diseases in China, 2020). Early identification and treatment of high-risk individuals with CHD are important factors in reducing both the incidence rate and mortality of cardiovascular diseases.

In these mutations, cytosine (C) is replaced with thymine (T), resulting in a valine substitution within the mature MTHFR enzyme that reduces its heat resistance and activity (Chango et al, 2000). The frequency of mutant t-alleles varies greatly across different populations, with Yadav et al (2018) describing the highest incidence for the t-allele in the European population at 64.3% and the lowest in the African population at 24%. Yang et al (2017) pointed out that MTHFR C677T polymorphism information in China is primarily associated with populations from the southeast coast of China. However, the small amount of data available for the entire region suggest that the distribution of these polymorphisms in different provinces is greatly varied and exhibits a clear geographical trend, increasing with initial increments in both latitude and longitude and then slowly decreasing.

The genotype frequencies for the CC, CT, and TT MTHFR C677T locus were reported as 23.1%, 50.1%, and 26.8%, respectively, in Beijing, with the CC genotype frequency decreasing in the Heilongjiang, Jilin, Hebei, Shandong, and Henan Provinces when compared to that of Beijing (Li et al, 2019). The CT genotype remains roughly the same across these regions, but their TT genotype frequency is significantly increased compared to the Beijing data. The present study involved the evaluation of 421 cases, including 156 with a CC (37%), 197 with a CT (47%), and 68 with a TT genotype (16%). Our results suggest that the MTHFR C677T CC genotype is significantly more common in the Gansu Province than in Beijing, while the CT genotype is equally prevalent in both the places. However, our data suggest that the TT genotype frequency is significantly lower in Gansu Province than in Beijing.

Hcy is an important risk factor for cardiovascular and cerebrovascular diseases. The MTHFR C677T mutation reduces the activity of the resultant enzymes due to reduced heat tolerance. This results in a reduction in the MTHFR-mediated methylation of Hcy and its product methionine leading to Hcy accumulation in the tissues, a decrease in folate levels, and hyperhomocysteinemia (Huang et al, 2022). Therefore, we decided to evaluate the effect of these genotypes on the folate and Hcy levels in CHD and non-CHD patients. Our evaluations revealed an expected increase in serum Hcy levels and a decrease in folate levels in the CHD group. Our data also showed an increase in the TT genotype frequency in the CHD group (p < 0.05) and a significant increase in Hcy levels in the TT group when compared to the CC and CT groups.

These data also revealed that the folate levels were significantly lower in TT samples than in CC or CT, consistent with the results of various previous studies. Further analysis showed a significant difference in Hcy/folate levels between the CT and CC and TT and CC genotypes but not between the CT and TT genotypes. The degree of CHD between different genotypic groups was evaluated using the syntax score, but no significant difference was observed. Bouzidi et al (2020) hypothesized that the CT and TT genotypes were positively correlated with the degree of coronary stenosis and the rate of in-stent restenosis. However, this is inconsistent with our results. This discrepancy may be due to the impact of various other factors such as region, environment, diet, and sample size. In the future, it will be necessary to expand the sample size for further verification.

The results of the univariate analysis showed that there were more men than women in the CHD group and that the serum TG and HDL levels increased significantly in CHD patients, while serum HDL levels decreased significantly. There were no significant differences in the levels of TC and LDL or complications between the two groups. Logistic regression analysis showed that TT genotype and serum Hcy and folate levels were associated with CHD. This evaluation also identified TT genotype and serum Hcy levels as risk factors for CHD and folate level as a protective factor. Based on these results, we suggest that a TT genotype at the MTHFR C677T locus is a molecular marker for increased risk of CHD in the Gansu population. This suggests that the TT genotype confers an increased genetic risk for CHD and that it should be added to the molecular evaluation of patients from the Gansu Province.

This study analyzed MTHFR C677T gene polymorphisms and their relationship with CHD in the Gansu population in the hope of improving the identification of vulnerable patients and the efficacy of both prevention and treatment strategies in this region of China. Given this, we suggest that the molecular characterization of the MTHFR C677T locus and careful monitoring of blood Hcy levels in vulnerable people should become standard practice. We propose that folate supplementation be evaluated as a preventative strategy for managing CHD in this population.

In conclusion, the TT genotype of MTHFR C677 affects the risk of CHD in Gansu residents, and this marker may be a predictor for other more traditional CHD risk factors. Thus, we suggest that the molecular characterization of the MTHFR gene may contribute to the development of personalized risk prediction and strategic health care planning in CHD patients. However, given the small sample size of this study, we suggest that these data should be validated in a more expansive study. In addition, future studies should further verify the exact genetic factors involved in the development of CHD and focus on the mechanism of genetic risk factors leading to the development of CHD and their interaction with environmental risk factors.

Availability of Data and Materials

The data that support the findings of this study are available from The Second Hospital of Lanzhou University, Lanzhou, China.

Footnotes

Disclosure Statement

No competing financial interests exist.

Funding Information

This study was funded by a research project grant from the Major Science and Technology special project of Gansu Province (20ZD7FA002), The TCM prevention and Treatment of major diseases scientific research project (GZKZD-2018-02), The Science and Technology Department of Gansu Province (21JR7RA399), The Lanzhou Science and Technology Bureau (2018-3-46, 2018-ZD-1), and the Cuiying Scientific and Technological Innovation Program of Lanzhou University Second Hospital (CY2021-BJ-A17).

Supplementary Material

Supplementary Data

References

Benincasa

, Spigna

, Cappelli

, et al. High incidence of MTHFR, CBS, and MTRR polymorphisms in vitiligo patients. Preliminary report in a retrospective study. Eur Rev Med Pharmacol Sci, 2019; 23(2):471–478; doi: 10.26355/eurrev_201901_16858.

Bhargava

, Ali

, Parakh

, et al. Higher incidence of C677T polymorphism of the MTHFR gene in North Indian patients with vascular disease. Vascular, 2012; 20(2):88–95; doi: 10.1258/vasc.2011.oa0320.

Botto

, Yang

. 5,10-Methylenetetrahydrofolate reductase gene variants and congenital anomalies: A HuGE review. Am J Epidemiol, 2000; 151(9):862–877; doi: 10.1093/oxfordjournals.aje.a010290.

Bouzidi

, Hassine

, Fodha

, et al. Association of the methylenetetrahydrofolate reductase gene rs1801133 C677T variant with serum homocysteine levels, and the severity of coronary artery disease. Sci Rep, 2020; 10(1):1–9; doi: 10.1038/s41598-020-66937-3.

Chango

, Boisson

, Barbe

, et al. The effect of 677C→T and 1298A→C mutations on plasma homocysteine and 5,10-methylenetetrahydrofolate reductase activity in healthy subjects. Br J Nutr, 2000; 83(6):593–596; doi: 10.1017/s0007114500000751.

Chi

, Gong

, Zheng

, et al. Correlation between Hcy, MTHFR polymorphism and susceptibility of coronary heart disease. Hebei Medical Journal, 2020; 24(8):1148–1151; doi: 10.3969/j.issn.1002-7386.2020.08.006.

Hou

, Zhon

, Deng

, et al. The role of MTHFR C677T and ALDH2 Glu504Lys polymorphism in acute coronary syndrome in a Hakka population in southern China. BMC Cardiovasc Disord, 2020; 11(20):127; doi:10.1186/s12872-020-01410-7.

Huang

, Li

, et al. Association of the methylenetetrahydro-folate reductase (MTHFR) gene variant C677T with serum homocysteine levels and the severity of ischaemic stroke: A case-control study in the southwest of China. J Int Med Res, 2022; 50(2):3000605221081632; doi: 10.1177/03000605221081632.

, Ye

, Gan

, et al. Analysis for polymorphism of MTHFR C677T gene in Han population in Beijing. J Clin Lab Sci, 2019; 37(2):156–160; doi: 10.13602/j.cnki,jcls.

10.

Liang

, Zou

, Li

, et al. Research progress of medicinal secondfry metabolites and gene cloning of dendrobium officinale. Med Plant, 2019; 10(3):16–18; doi: 10.19600/j.cnki.issn2152-3924.2019.03.004.

11.

McPherson

, Tybjaerg-Hansen

. Genetics of coronary artery disease. Circ Res, 2016; 118(4):564–578; doi: 10.1161/CIRCRESAHA.115.306566.

12.

Musunuru

, Kathiresan

. Genetics of common, complex coronary artery disease. Cell, 2019; 177(1):32–145; doi: 10.1016/j.cell.2019.02.015.

13.

Ong

, Serruys

, Mohr

, et al. The SYNergy between per-cutaneous coronary intervention with TAXus and cardiac surgery (SYNTAX) study: design, rationale, and run-in phase. Am Heart J, 2006; 151(6):1194–1204; doi: 10.1016/j.ahj.2005.07.017.

14.

Stajnko

, Slejkoveg

, Mazej

, et al. Arsenic metabolites;selenium; and AS3MT, MTHFR, AQP4, AQP9, SELENOP, INMT, and MT2A polymorphisms in Croatian-Slovenium population from PHIME-CROME study. Environ Res, 2019; 170:301–319; doi: 10.1016/j.envres.2018.11.045.

15.

The Writing Committee of the Report on Cardiovascular Health and Diseases in China. China cardiovascular health and disease report 2020 compilation group key points of report on cardiovascular health and diseases in China. Chin J Cardiovasc Res, 2020; 19(7):582–590; doi: 10.3969/j.issn.1672-5301.2021.07.002.

16.

Vinkhuyzen

, Wray

, Yang

, et al. Estimation and partition of heritability in human populations using whole-genome analysis methods. Annu Rev Geneti, 2013; 47:75–95; doi: 10.1146/annurev-genet-111212-133258.

17.

Wilcken

, Bamforth

, Li

, et al. Geographical and ethnic variation of the 677C > T allele of 5,10 methylenetetrahydrofolate reductase (MTHFR): findings from over 7000 newborns from 16 areas world wide. J Med Genet, 2003; 40(8):619–625; doi: 10.1136/jmg.40.8.619.

18.

Yadav

, Kumar

, Gupta

, et al. Distribution of MTHFR C677T gene polymorphism in healthy north indian population and an updated Meta-analysis. Indian J Clin Biochem, 2018; 32(4):399–410; doi: 10.1007/s12291-016-0619-0.

19.

Yang

, Fan

, Zhi

, et al. Geographical and ethnic distribution of MTHFR gene polymorphisms and their associations with diseases among Chinese population. Clin Genet, 2017; 92(3):243–258; doi: 10.1111/cge.12929.

20.

Zaghloul

, Lorgoveanu

, Desai

, et al. Methylenetetrahydrofolate reductase polymorphism and premature coronary artery disease. Cureus, 2019; 11(6):e5014; doi: 10.7759/cureus.5014.

21.

ZHao

, Hou

, Wu

, et al. Analysis of genetic polymorphism of methylenetetrahydrofolate reductase in a large ethnic Hakka population in southern China. Medicine, 2018; 97(50):e13332; doi: 10.1097/MD.0000000000013332.

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