MTHFR

Chr 1ARAD

methylenetetrahydrofolate reductase

The protein catalyzes the conversion of 5,10-methylenetetrahydrofolate to 5-methyltetrahydrofolate, a co-substrate required for homocysteine remethylation to methionine. Mutations cause homocystinuria due to MTHFR deficiency with autosomal recessive inheritance, while certain variants increase susceptibility to neural tube defects, thromboembolism, and vascular disease. Loss-of-function mutations result in enzyme deficiency leading to elevated homocysteine levels and disrupted methionine metabolism.

OMIMResearchSummary from RefSeq, OMIM, Mechanism
LOFmechanismAR/ADLOEUF 0.925 OMIM phenotypes
Clinical SummaryMTHFR
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Gene-Disease Validity (ClinGen)
homocystinuria due to methylene tetrahydrofolate reductase deficiency · ARDefinitive

Definitive — sufficient evidence for diagnostic panels

Population Constraint (gnomAD)
Low constraint (pLI 0.00) — loss-of-function variants are relatively tolerated in the population.
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Clinical Trials
8 active or recruiting trials — potential therapeutic options may be available

Population Genetics & Constraint

gnomAD v4 — loss-of-function & missense intolerance

Tolerant — LoF & missense variants common in population
LoF Constraint
0.92LOEUF
pLI 0.000
Z-score 1.90
OE 0.63 (0.450.92)
Tolerant

Typical tolerance to LoF variation

Missense Constraint
0.90Z-score
OE missense 0.87 (0.800.95)
342 obs / 391.9 exp
Tolerant

Mild missense constraint

Observed / Expected Ratios
LoF OE0.63 (0.450.92)
00.351.4
Missense OE0.87 (0.800.95)
00.61.4
Synonymous OE1.14
01.21.6
LoF obs/exp: 20 / 31.5Missense obs/exp: 342 / 391.9Syn Z: -1.37
Curated Mechanism (G2P)Gene2Phenotype (DDG2P) ↗
definitiveMTHFR-related methylenetetrahydrofolate deductase deficiencyLOFAR

Predictions shown for reference only — model trained on dominant genes, not applicable to AR conditions.

DN
0.6745th %ile
GOF
0.5169th %ile
LOF
0.2582th %ile

The Badonyi & Marsh prediction model was trained exclusively on dominant disease genes. Predictions are not reliable for genes with autosomal recessive inheritance and are shown at reduced opacity for reference only.

Predictions from Badonyi M, Marsh JA. PLoS ONE. 2024;19(8):e0307312.

ClinVar Variant Classifications

0 submitted variants in ClinVar

Protein Context — Lollipop Plot

MTHFR · protein map & ClinVar variants

Showing all ClinVar variants across the protein. Search a specific variant to highlight its position.

3D Protein StructureAlphaFold

Clinical Trials

Active and recruiting trials from ClinicalTrials.gov

Overweight and ObesityLupus Erythematosus

Methyl-donor Nutrient Supplementation and Methylation Profile in Lupus Patients With Obesity

ENROLLING BY INVITATION
NCT05097365Phase NAUniversity of Sao PauloStarted 2022-01-01
Vitamin B12 + folic acid supplementationPlacebo supplementation
Infant NeurodevelopmentNutritionMethylation

Maternal Methyl-Nutrient Status and Infant Neurodevelopment Study

NOT YET RECRUITING
NCT07568561Far Eastern Memorial HospitalStarted 2026-05-06
Epilepsy

Precision Medicine in the Treatment of Epilepsy

RECRUITING
NCT05450822Gitte Moos KnudsenStarted 2022-02-18
LevetiracetamLevetiracetam TabletsLamotrigine tablet
Silent Myocardial IschemiaAcute Myocardial Infarction

Silent Myocardial Ischemia in Patients Undergoing Non-oncological Abdominal Surgeries

RECRUITING
NCT06536686University Medical Centre LjubljanaStarted 2024-07-01
Silent myocardial ischemia, STEMI
Blood PressurePregnancy

Optimal Nutrition for Prevention of Hypertension in Pregnancy

ACTIVE NOT RECRUITING
NCT04723836Phase NAUniversity of UlsterStarted 2017-03-01
Riboflavin (5mg)5-methyltetrahydrofolate (400µg)Placebo
Hyperhomocysteinemia

Evaluation of a Genetically Determined Personalized Approach in Prescribing Biologically Active Substances in Patients With Elevated Blood Homocysteine Levels.

RECRUITING
NCT06264570Phase NAS.LAB (SOLOWAYS)Started 2023-10-23
B-TMG supplementationB-SAM supplementationB-TMG placebo
Pancreatic Cancer

Pancreatic Cancer Genetics

RECRUITING
NCT01102569Columbia UniversityStarted 2008-01
Hereditary Dysfibrinogenemia

Genomics of Fibrin Clot Structure in Patients With Constitutional Dysfibrinogenemia

ACTIVE NOT RECRUITING
NCT05233384University Hospital, Clermont-FerrandStarted 2022-07-28
Blood test
Clinical Literature
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