rs1801133
NM_005957.5(MTHFR):c.665C>T (p.Ala222Val)
- methotrexate response - ToxicityDrug response · ★★★ · germline
- Homocystinuria due to methylene tetrahydrofolate reductase deficiencyConflicting interpretations · ★ · unknown
- Neural tube defects, folate-sensitive (NTDFS)Likely benign · ★ · unknown
- MTHFR THERMOLABILE POLYMORPHISMConflicting interpretations · germline
- Thrombophilia due to thrombin defect (THPH1)Uncertain significance · unknown
- Gastrointestinal stromal tumorUncertain significance · germline
- not providedUncertain significance · ★★ · germline
- See casesUncertain significance · ★ · unknown
- not specifiedBenign · ★ · germline
gnomAD allele frequency 2.57e-1
rs1801133 is a genetic variant located in the MTHFR gene. dbsnp · gene
In gnomAD, rs1801133 has an overall allele frequency of 25.7%. gnomad · frequency
In ClinVar, rs1801133 is classified as Drug response (toxicity) for methotrexate response (3 review stars, germline; last evaluated 2021-03-24). clinvar · classificationclinvar · review confidenceclinvar · originclinvar · assertion date
In ClinVar, rs1801133 is classified as Conflicting interpretations for Homocystinuria due to methylene tetrahydrofolate reductase deficiency (1 review star; last evaluated 2025-02-03). clinvar · classificationclinvar · review confidenceclinvar · assertion date
In ClinVar, rs1801133 is classified as Likely benign for Neural tube defects, folate-sensitive (NTDFS) (1 review star; last evaluated 2019-05-28). clinvar · classificationclinvar · review confidenceclinvar · assertion date
In ClinVar, rs1801133 is classified as Conflicting interpretations for MTHFR THERMOLABILE POLYMORPHISM (0 review stars, germline; last evaluated 2023-09-29). clinvar · classificationclinvar · review confidenceclinvar · originclinvar · assertion date
In ClinVar, rs1801133 is classified as Uncertain significance for Thrombophilia due to thrombin defect (THPH1) (0 review stars; last evaluated 2017-12-30). clinvar · classificationclinvar · review confidenceclinvar · assertion date
In ClinVar, rs1801133 is classified as Uncertain significance for Gastrointestinal stromal tumor (0 review stars, germline). clinvar · classificationclinvar · review confidenceclinvar · origin
In ClinVar, rs1801133 is classified as Uncertain significance for not provided (2 review stars, germline; last evaluated 2024-11-22). clinvar · classificationclinvar · review confidenceclinvar · originclinvar · assertion date
In ClinVar, rs1801133 is classified as Uncertain significance for See cases (1 review star; last evaluated 2022-01-06). clinvar · classificationclinvar · review confidenceclinvar · assertion date
In ClinVar, rs1801133 is classified as Benign for not specified (1 review star, germline; last evaluated 2016-04-25). clinvar · classificationclinvar · review confidenceclinvar · originclinvar · assertion date
retrieved 2026-08-03 · facts a94457ccaa8cfafb · meta/llama-3.1-8b-instruct · prompt 4.0.1 · schema 3.0.0
Educational information only — not medical advice, a diagnosis, or a clinical interpretation. A variant's significance can be uncertain, conflicting, or dependent on your full clinical and family context. Consult a qualified genetics professional or genetic counselor before drawing any conclusion.