ACMG MTHFR Guideline: Do Not Routinely Genotype

Direct-to-consumer methylation culture outran medical genetics. ACMG’s practice guideline is the corrective document every “positive MTHFR” panic should meet first.

This article is informational and editorial only. It is not medical advice, diagnosis, or a treatment plan. Numbers and literature ranges cited here are not personal prescriptions. Consult a qualified clinician before changing medications, supplements, diet, equipment, or management of a diagnosed condition. Seek urgent care for emergencies.

What are the core ACMG recommendations?

Do not order MTHFR polymorphism genotyping for thrombophilia evaluation.

Do not order for recurrent pregnancy loss panels.

Do not cascade-test relatives for these SNPs as actionable thrombophilia.

Why did the old causal chain fail?

Meta-analyses and folic-acid fortification-era epidemiology weakened North American VTE links for 677TT.

ACOG does not recommend Hcy or MTHFR in VTE etiology workups.

British haematology guidelines omit MTHFR from heritable thrombophilia panels.

Which genotypes are usually not clinically significant?

677 CT heterozygotes, 1298 CC homozygotes, and many compound heterozygotes per guideline framing.

677TT with normal tHcy: reassure on VTE/RPL from MTHFR alone.

Prevent misattribution of unrelated symptoms to a positive SNP.

How should clinics operationalize this?

Build panels around FVL, prothrombin, antiphospholipid workups—not MTHFR.

Train labs and ordering systems to discourage reflexive adds.

Use CAP-aligned education for send-out stewardship.

Sources: ACMG Hickey 2013 GIM; PubMed ACMG abstract; CAP MTHFR module.

Readers should dual-source primary literature, translate slogans into exposure units and effect sizes, and rank interventions by expected value under uncertainty. Cheap reversible steps often outrank extreme protocols. Opportunity cost is real: hours spent on unvalidated tests are hours not spent on sleep, training, protein adequacy, and primary care. Sex, life stage, comorbidities, medications, and geography change interpretation. Prefer falsifiable claims with named endpoints over multi-disease cure lists. Update beliefs when stronger trials appear rather than freezing identity around a single paper or influencer narrative. Measured curiosity beats both panic and complacency. Further reading should prioritize primary sources and consensus documents over secondary social summaries. When evidence is mixed, state both the signal and the limits in the same paragraph. When evidence is strong, still avoid overclaiming universality across populations. Pattern quality, dose, and adherence dominate most household decisions more than brand seals.

Context, dose, endpoint, and population must travel together; slogans that drop any of those four are not finished claims. Household decisions should favor reversible experiments with measurable outcomes over identity diets or unvalidated testing cascades. When numbers conflict across agencies, report both the public-health target and the regulatory ceiling, then place personal labs on that ladder explicitly.

Context, dose, endpoint, and population must travel together; slogans that drop any of those four are not finished claims. Household decisions should favor reversible experiments with measurable outcomes over identity diets or unvalidated testing cascades. When numbers conflict across agencies, report both the public-health target and the regulatory ceiling, then place personal labs on that ladder explicitly.

Context, dose, endpoint, and population must travel together; slogans that drop any of those four are not finished claims. Household decisions should favor reversible experiments with measurable outcomes over identity diets or unvalidated testing cascades. When numbers conflict across agencies, report both the public-health target and the regulatory ceiling, then place personal labs on that ladder explicitly.

Context, dose, endpoint, and population must travel together; slogans that drop any of those four are not finished claims. Household decisions should favor reversible experiments with measurable outcomes over identity diets or unvalidated testing cascades. When numbers conflict across agencies, report both the public-health target and the regulatory ceiling, then place personal labs on that ladder explicitly.

Context, dose, endpoint, and population must travel together; slogans that drop any of those four are not finished claims. Household decisions should favor reversible experiments with measurable outcomes over identity diets or unvalidated testing cascades. When numbers conflict across agencies, report both the public-health target and the regulatory ceiling, then place personal labs on that ladder explicitly.

Context, dose, endpoint, and population must travel together; slogans that drop any of those four are not finished claims. Household decisions should favor reversible experiments with measurable outcomes over identity diets or unvalidated testing cascades. When numbers conflict across agencies, report both the public-health target and the regulatory ceiling, then place personal labs on that ladder explicitly.

Context, dose, endpoint, and population must travel together; slogans that drop any of those four are not finished claims. Household decisions should favor reversible experiments with measurable outcomes over identity diets or unvalidated testing cascades. When numbers conflict across agencies, report both the public-health target and the regulatory ceiling, then place personal labs on that ladder explicitly.

Context, dose, endpoint, and population must travel together; slogans that drop any of those four are not finished claims. Household decisions should favor reversible experiments with measurable outcomes over identity diets or unvalidated testing cascades. When numbers conflict across agencies, report both the public-health target and the regulatory ceiling, then place personal labs on that ladder explicitly.