GENETIC METHYLATION TESTING

Genetic Methylation Testing — the methylation cycle involves dozens of genes beyond MTHFR, and whole genome sequencing evaluates all of them — MTRR, MTR, BHMT, CBS, COMT, MAT1A, AHCY — providing the complete methylation genetic profile.

Whole genome sequencing evaluates all methylation cycle genes simultaneously — not just the two common MTHFR variants (C677T, A1298C) tested by standard panels, but every variant across every gene in the folate, methionine, and transsulfuration pathways.

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About this condition

Genetic Methylation Testing

The methylation cycle (one-carbon metabolism) is a central metabolic pathway that provides methyl groups for DNA methylation, neurotransmitter synthesis, detoxification, phospholipid production, and homocysteine metabolism. The pathway involves multiple enzymes: MTHFR (methylenetetrahydrofolate reductase — converts 5,10-methyleneTHF to 5-methylTHF, the active folate form), MTR (methionine synthase — converts homocysteine to methionine using B12), MTRR (methionine synthase reductase — regenerates active B12 for MTR), BHMT (betaine-homocysteine methyltransferase — alternative homocysteine conversion pathway), CBS (cystathionine beta-synthase — transsulfuration pathway), and COMT (catechol-O-methyltransferase — neurotransmitter methylation).

MTHFR C677T (rs1801133) is the most studied methylation variant: homozygous TT genotype (~10-12% of European ancestry) reduces MTHFR enzyme activity by ~70%, potentially causing elevated homocysteine (a cardiovascular risk factor) and reduced methylfolate availability. MTHFR A1298C (rs1801131) reduces activity by ~35% in homozygotes. However, the methylation cycle is a network — individual variants in other genes (MTRR A66G, MTR A2756G, CBS C699T, COMT Val158Met) can compound or compensate for MTHFR variants. Standard MTHFR-only tests miss this network complexity.

Clinical implications of methylation variants include: elevated homocysteine (cardiovascular risk — addressable with methylfolate and active B12 supplementation), neural tube defect risk in pregnancy (MTHFR TT women benefit from methylfolate rather than folic acid), variable drug metabolism (COMT Val158Met affects catecholamine metabolism, pain sensitivity, and response to certain medications), and CBS variants that may affect sulfur metabolism and detoxification pathways. Comprehensive methylation testing that evaluates the entire pathway — not just one or two MTHFR variants — provides a complete picture for personalized supplementation.

Standard MTHFR tests check only 2 variants (C677T and A1298C). The methylation cycle involves 20+ genes with hundreds of functional variants. WGS evaluates all of them — providing the comprehensive profile that incomplete testing cannot.

Gene locus
MTHFR (1p36.22), MTR (1q43), MTRR (5p15.31), BHMT (5q14.1), CBS (21q22.3), COMT (22q11.21), MAT1A (10q22.3), AHCY (20q11.22)

Methylation is a pathway, not a single gene. Testing only MTHFR C677T and A1298C misses the majority of genetic variation that affects folate, B12, and homocysteine metabolism. WGS evaluates the complete pathway.

MTHFR-only testing misses the network — MTRR, MTR, BHMT, and CBS variants can compound or compensate for MTHFR genotype

A patient with MTHFR 677 CT (heterozygous, mild reduction) who also carries MTRR 66 GG (reduced B12 recycling) and MTR 2756 GG (reduced methionine synthase activity) may have significantly impaired methylation — more than would be predicted from the MTHFR result alone. Conversely, a patient with MTHFR 677 TT but favorable BHMT and CBS genotypes may compensate through alternative pathways. Only comprehensive testing of the entire pathway reveals the net methylation capacity.

COMT Val158Met affects pain sensitivity, catecholamine metabolism, and response to HRT — a pharmacogenomic variant with broad clinical implications

COMT Val158Met (rs4680) determines COMT enzyme activity: Val/Val (high activity, rapid catecholamine degradation — 'warrior' phenotype), Met/Met (low activity, higher catecholamine levels — 'worrier' phenotype), and Val/Met (intermediate). This variant affects pain sensitivity, stress response, cognitive performance under pressure, estrogen metabolism, and response to certain medications. COMT is part of the methylation cycle — it uses SAM (S-adenosylmethionine) as its methyl donor. WGS provides COMT genotyping alongside all other methylation genes.

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