Correlations between methylenetetrahydrofolate reductase gene polymorphisms and venous thromboembolism: A meta-analysis of 99 genetic association studies

Homozygous MTHFR C677T carriers develop idiopathic portal vein thrombosis 20 years earlier than wild type

The aim of this study was to evaluate the impact of methylene tetrahydrofolate reductase (MTHFR) rs1801133 (C→T667 transition) on age at first idiopathic portal vein thrombosis (PVT) and to identify clinical and/or laboratory variables influencing age at first PVT, including plasma homocysteine and the prothrombin rs1799963 PT (G→A transition at position 20210) (PT) mutation. A retrospective cross-sectional cohort, including 15 MTHFR TT, 32 MTHFR TC and 22 MTHFR CC idiopathic PVT participants contributing demographics, age at PVT, plasma concentrations of homocysteine and of natural anticoagulants. MTHFR TT carriers presented with a lower age at PVT than heterozygous or wild-type genotypes (31 ± 8 vs. 48 ± 15 vs. 52 ± 13 years, P  = 0.001) and were more likely to have a plasma HC concentration above the cut-off (73.3 vs. 32 vs. 50%, P  = 0.04). MTHFR TT and protein C predicted age at PVT ( P  < 0.0001 and P  = 0.06); MTHFR TT predicted plasma homocysteine ( P  = 0.05). In the MTHFR TT group, plasma homocysteine inversely related to protein C ( P  = 0.03). Plasma homocysteine predicted the extent of PVT ( P  = 0.03). Compound MTHFR TT + PT GA did not lower age at first PVT compared to MTHFR TT alone (35 ± 9 vs. 30 ± 8 years). MTHFR TT is associated with a 20-year earlier PVT presentation than heterozygous and wild-type MTHFR genotypes. The inverse relation between plasma homocysteine and protein C contributes to the prematurity of PVT in the MTHFR TT group, whereas plasma homocysteine contributes to the extent of PVT. The recent exclusion of MTHFR genotyping from the thrombophilia screen needs revisiting in this setting.

Homozygous MTHFR C667T carriers ≤45 years old develop central retinal vein occlusion five years earlier than wild type

PURPOSE

To assess age at 1st central retinal vein occlusion (CRVO) in carriers ≤ 45 years old of the methylenetetrahydrofolate reductase (MTHFR) C667T genotype compared to heterozygous and wild type, and to identify predictors of age at CRVO.

METHODS

Retrospective cohort study consisting of 18 MTHFR TT, 23 MTHFR TC and 28 MTHFR CC participants; information regarding age, sex, age at CRVO, history of dyslipidaemia, hypertension, smoking and plasma HC measured by immunoassay were collected.

RESULTS

Age at CRVO was lower in MTHFR TT than MTHFR TC and CC (32 ± 6 vs 38 ± 5 vs 37 ± 6 years, respectively, p = 0.005); plasma HC was higher in MTHFR TT than in the other genotypes [14.4 (10.8, 19.6) vs 10.4 ((8.6,12.5) vs 8.5 ((7.5,9.8) μmol/l, p = 0.0002). Smoking (cigarettes/day) independently predicted age at CRVO (p = 0.039) and plasma HC (p = 0.005); smoking status (yes/no) predicted ischemic CRVO (p = 0.01) that was more common in the MTHFR TT group (p = 0.006).

CONCLUSIONS

Carriers of the MTHFR TT genotype ≤ 45 years old develop their 1st CRVO on average 5 years earlier than the MTHFR CC genotype; smoking contributes to the prematurity and severity of CRVO in MTHFR TT carriers.

A case report of vaccine-induced immune thrombotic thrombocytopenia (VITT) with genetic analysis

The emergence of the rare syndrome called vaccine-induced immune thrombocytopenia and thrombosis (VITT) after adenoviral vector vaccines, including ChAdOx1 nCov-19, raises concern about one's predisposing risk factors. Here we report the case of a 56-year-old white man who developed VITT leading to death within 9 days of symptom onset. He presented with superior sagittal sinus thrombosis, right frontal intraparenchymal hematoma, frontoparietal subarachnoid and massive ventricular hemorrhage, and right lower extremity arterial and venous thrombosis. His laboratory results showed elevated D-dimer, C-reactive protein, tissue factor, P-selectin (CD62p), and positive anti-platelet factor 4. The patient's plasma promoted higher CD62p expression in healthy donors' platelets than the controls. Genetic investigation on coagulation, thrombophilia, inflammation, and type I interferon-related genes was performed. From rare variants in European or African genomic databases, 68 single-nucleotide polymorphisms (SNPs) in one allele and 11 in two alleles from common SNPs were found in the patient genome. This report highlights the possible relationship between VITT and genetic variants. Additional investigations regarding the genetic predisposition of VITT are needed.

Venous Thrombosis Has a Constellation of Different Risk Factors: A Case Report and State-of-the-Art Review

Splanchnic venous thrombosis and cerebral venous thrombosis are uncommon manifestations of venous thromboembolism (VTE) that have been associated with inherited thrombophilias. Hyperhomocysteinemia is an established risk factor for thrombosis, and methylenetetrahydrofolate reductase (MTHFR) mutation is the most common genetic alteration in this condition. The association between MTHFR mutations, mild to moderate elevations in homocysteine, and the risk for thrombosis is controversial. Pylephlebitis, also known as suppurative portal vein thrombophlebitis, usually originates from an intra-abdominal infectious process. It is a condition with high morbidity and mortality, partly due to its late diagnosis, and antibiotics are the gold standard treatment. The purpose of anticoagulation is dubious. We describe the case of a 60-year-old male with a previous history of venous sinus thrombosis and MTHFR A1298C mutation with mild homocysteine ​​elevation who presented with signs and symptoms of intra-abdominal infection and whose abdominopelvic computed tomography (CT) with intravenous contrast showed splanchnic-vein thrombosis. Through this complex case, the authors present a review of the current state of the art on VTE, hyperhomocysteinemia, and pylephlebitis, emphasizing the need for a holistic view of the patient in the decision-making process.

Liver Cirrhosis Patients Homozygous for MTHFR C677T Develop Portal Vein Thrombosis 8 Years Earlier Than Wild Type

BACKGROUND AND AIM

Age at portal vein thrombosis (PVT) in liver cirrhosis (LC) carriers of the methylene tetrahydrofolate reductase (MTHFR) rs1801133 (C → T667 transition) polymorphism has never been addressed; we compared age at PVT in LC patients genotyped for the MTHFR and explored the interrelated clinical and laboratory factors predicting age at PVT.

APPROACH AND RESULTS

Retrospective cross-sectional cohort study. PVT participants: MTHFR CC n = 36, MTHFR CT n = 53, MTHFR TT n = 19; age, sex, age at PVT, Child-Pugh score, rs1799963 PT polymorphisms (G → A 20,210 transition), plasma HC and natural anticoagulants available for all participants. Age at PVT was lower in MTHFR TT than CT and CC (56 ± 13 vs. 57 ± 13 vs. 64 ± 9 years, p = 0.001); median (IQR) plasma HC was higher in MTHFR TT than in the other groups [(17 (9.4, 23.3) vs 13 (8,14.7) vs 11 (8.9, 12.7) μmol/l, p = 0.03)]. MTHFR TT, male gender and protein C predicted age at PVT (p = 0.02, p = 0.04 and p = 0.08); MTHFR TT and Child-Pugh score predicted plasma HC (p = 0.005 and p = 0.01) as well as low plasma protein C (p < 0.0001 and p = 0.0002). Plasma HC inversely related to protein C in the MTHFR TT group (p < 0.0001). Compound MTHFR TT with PT GA had lower age at PVT compared to MTHFR TT alone (49 ± 18 vs 58 ± 12 years).

CONCLUSIONS

MTHFR TT anticipates PVT associated with LC by an average of 8 years; MTHFR TT associates with severity of liver disease and to high plasma HC; the latter may contribute to the prematurity of PVT by interfering with the anticoagulant activity of protein C.

Impact of hereditary thrombophilia on cancer-associated thrombosis, tumour susceptibility and progression: A review of existing evidence

Venous thromboembolism (VTE) is a cardiovascular disorder frequently diagnosed among cancer patients. Aside from being common, VTE severely deteriorates the prognosis of these patients as they face a higher risk of morbidity and mortality, which makes clinical tools able to identify the patients more prompt to thrombogenesis very attractive. Over the years, several genetic polymorphisms have been linked with VTE susceptibility in the general population. However, their clinical usefulness as predictive biomarkers for cancer-related VTE is yet unclear. Furthermore, as a two-way association between cancer and VTE is well-recognized, with haemostatic components fuelling tumour progression, haemostatic gene polymorphisms constitute potential cancer predictive and/or prognostic biomarkers as well. Thus, in this article, we review the existing evidence on the role of these polymorphisms on cancer-related VTE and their impact on cancer onset and progression. Despite the promising findings, the existing studies had inconsistent results most likely due to their limited statistical power and population heterogeneity. Future studies are therefore required to clarify the role of these polymorphisms in setting of malignancy.

Earlier onset of peripheral arterial thrombosis in homozygous MTHFR C677T carriers than in other MTHFR genotypes: a cohort study

To investigate whether age at first presentation of pure peripheral arterial thrombosis (PAT) in lower and upper limbs and in the splanchnic circulation occurs earlier in carriers of the methylenetetrahydrofolate reductase (MTHFR) T677T genotype compared to the heterozygous and wild type and to identify predictors of a possible earlier onset. Retrospective cohort study on 27 MTHFR TT, 29 MTHFR TC and 29 MTHFR CC participants; data regarding age, sex, age at PAT, clinical history (dyslipidaemia, hypertension, smoking, obesity) and homocysteine (HC) measured by immunoassay were collected. Age at PAT was lower in MTHFR TT than MTHFR TC and CC (43 ± 9 vs 47 ± 9 vs 51 ± 4 years, respectively, p = 0.02); plasma HC was higher in MTHFR TT than in the other groups (25 ± 19 vs 12.7 ± 6.7 vs 11.3 ± 3.3 μmol/l, respectively, p < 0.001) while the activated partial thromboplastin ratio (aPTTr) was lower in MTHFR TT than in other genotypes (0.90 ± 0.10 vs 0.97 ± 0.12 vs 0.97 ± 0.08 μmol/L p < 0.001). Among categorical variables, MTHFR TT and dyslipidaemia independently predicted age at AT (p = 0.01 & p = 0.03, respectively) whereas among the continuous variables HC independently predicted age at PAT (p = 0.02) as well as the aPTTr (p = 0.001); smoking predicted lower limb PAT (p = 0.005). MTHFR TT carriers develop their first PAT an average of 4 and 8 years earlier than MTHF CT and CC genotypes; MTHFR TT, dyslipidaemia and plasma HC contribute to the prematurity of the PAT while the interplay between elevated HC and smoking may affect type of arterial district occlusion.

Homozygous methylentetrahydrofolate reductase C667T genotype anticipates age at venous thromboembolism by one decade

The aim of the study was to compare age at first venous thromboembolism (VTE), plasma homocysteine and activated partial thromboplastin time ratio (aPTTr) amongst unprovoked VTE patients with the methylentetrahydrofolate reductase (MTHFR) C667T genotypes, and to identify predictors of age at first VTE, of plasma homocysteine and of the aPTTr; to evaluate whether heterozygous or homozygous prothrombin (PT) G20210A mutation lowered the age at first VTE when associated with MTHFR TT. Retrospective cohort study on 259 MTHFR TT, 76 MTHFR TC and 64 MTHFR CC participants with unprovoked VTE; each participant contributed age, sex, age at VTE, history of dyslipidaemia, hypertension, smoking, homocysteine (measured by enzyme immunoassay) and aPTTr (measured by standard coagulation assay). Age at first VTE was lower in MTHFR TT than MTHFR TC and CC (41 ± 14 vs. 50 ± 16 vs. 51 ± 12 years, respectively, P < 0.0001); plasma homocysteine was higher in MTHFR TT than in the other groups (22 ± 21 vs. 12 ± 11.6 vs. 10 ± 3.3 μmol/l, respectively, P = 0.0005) whilst aPTTr was not different. MTHFR TT independently predicted age at first VTE (P = 0.001), plasma homocysteine (P < 0.0001) alongside sex (P = 0.0007), age and smoking (P = 0.03 for both). Compound MTHFR TT with PT GA or AA had no lowering effect on age at first VTE compared with MTHFR TT alone (41 ± 13 vs. 41 ± 14 years). Plasma homocysteine inversely related to aPTTr in the MTHFR TT group (P = 0.003). MTHFR TT anticipates age at first VTE by an average of 10 years compared with MTHFR TC and CC genotypes.

Prevalence of thrombophilia-associated genetic risk factors in blood donors of a regional hospital in southern Brazil

Introduction

Thromboembolic events occur due to an imbalance in the hemostasis and some factors associated with this condition can be inherited. In order to evaluate the frequency of genotypes considered to be common hereditary risk factors for thrombophilia associated with venous thrombosis (g.1691G > A and g.20210G > A) and hyperhomocysteinemia (g.677C > T and g.1298A > C), samples from voluntary healthy blood donors at the Hospital de Clínicas de Porto Alegre were tested.

Methods

We examined 325 blood samples from blood donors collected from October 2017 to July 2018. Blood was collected on filter paper and the DNA was extracted for single nucleotide polymorphisms (SNPs) analysis using the qualitative real time polymerase chain reaction.

Results

The calculated frequencies of each genetic variant in heterozygosity were 4% for the FV gene (g.1691G > A), 4% for the F2 gene (g.20210G > A) and 42% and 39% for methylenetetrahydrofolate reductase (MTHFR), g.677C > T and g.1298A > C, respectively. Only the genetic variants of MTHFR were found in homozygosity, with frequencies of 14% and 6% (g.677C > T and g.1298A > C), respectively.

Discussion

Altogether, these results describe the frequencies of genetic variants associated with venous thrombosis and hyperhomocysteinemia in the analyzed group and are important to enhance our current knowledge about the genetic profiles of Brazilian blood donors.

Prevalence of methylenetetrahydrofolate reductase gene polymorphisms (C677T, and A1298C) among Saudi children receiving dental treatment

BACKGROUND

Methylenetetrahydrofolate reductase, the encoded by the MTHFR gene, plays a crucial role in converting the amino acid homocysteine to methionine. Two polymorphisms of the MTHFR gene, C677T and A1298C, reportedly reduce enzyme activity, resulting in hyperhomocysteinemia. Patients with C677T and A1298C polymorphisms may be at higher risk for developing abnormal hyperhomocysteinemia, which has been linked to catastrophic neurological including fatal outcomes.

OBJECTIVE

Determine the prevalence of the MTHFR gene variants C677T and A1298C among pediatric dental patients treated at King Abdulaziz University Hospital.

DESIGN

Cross-sectional.

SETTING

Clinics of pediatric dentistry department.

SUBJECTS AND METHODS

Healthy Saudi children 6-12 years old with no known allergies were screened for eligibility between May and December 2019. A single investigator collected saliva samples. The MTHFR C677T and A1298C polymorphisms were analyzed using polymerase chain reaction and restriction fragment length polymorphism.

MAIN OUTCOME MEASURE

The prevalence of MTHFR gene variants (C677T and A1298C) among the subjects.

SAMPLE SIZE

138.

RESULTS

MTHFR C677T polymorphism was present in 36.2% of the sample and 90.0% of children carrying this allele were heterozygotes. MTHFR A1298C polymorphism was present in 91.3% of the sample and 77.0% of the children carrying this allele were heterozygotes. No linkage disequilibrium between MTHFR C677T and MTHFR A1298C was observed within this sample.

CONCLUSIONS

Our study found a high frequency of the MTHFR A1298C genotype, which was substantially more abundant than expected based on a Hardy-Weinberg distribution. Therefore, caution is advised in using N2O in Saudi children as the increased prevalence of this MTHFR allele may increase the incidence of serious adverse effects among these children.

LIMITATIONS

Further studies are recommended with a larger sample size from randomly selected hospitals from different regions of Saudi Arabia.

CONFLICT OF INTEREST

None.

Genetic and environmental factors associated with homocysteine concentrations in a population of healthy young adults. Analysis of the MAGNETIC study

BACKGROUND AND AIMS

Elevated homocysteine concentration is associated with a higher risk of cardiovascular disease. The aim of our study was to determine the environmental and genetic factors associated with serum homocysteine concentration in healthy young adults. Moreover, we aimed to determine the cutoff value of homocysteine concentration for predicting unfavorable MTHFR genotype and to investigate whether this association is modified by dietary patterns and serum folate status.

METHODS AND RESULTS

A total of 744 healthy individuals, aged 18-35 years, were included in the study. Diet quality was assessed by establishing diet quality scores and adherence to the pro-Healthy Diet Index (pHDI) and non-Healthy Diet Index (nHDI). Genotyping was performed using the TaqMan method. Multivariate analysis showed that pHDI, creatinine, folate concentrations, and the T/T genotype of the C677T polymorphism in MTHFR, as well as the interaction between the T/T genotype of MTHFR (C677T polymorphism) and folate level, were most strongly related to homocysteine concentrations. The specificity of a homocysteine >13.1 μmol/l in predicting T/T homozygous status was 76% (area under the curve 0.68).

CONCLUSION

Healthy dietary patterns, folate, and creatinine levels, as well as the C677T polymorphism, proved to be the strongest predictors of homocysteine concentrations. T/T genotype of MTHFR modifies the relationship between folate and homocysteine.