MTHFR Gene (Methylenetetrahydrofolate Reductase)

About this gene

Key enzyme in folate metabolism affecting methylation and homocysteine levels

Converts folate to its active form (5-MTHF) essential for DNA synthesis and methylation

rs2274976 MTHFR R594Q Population frequency: 5.0%

Genotype	Impact	What it means
GG (Normal)	Normal	Normal MTHFR activity at this position. Maintain folate, B12 and B6 intake.
GA (Carrier)	Low impact	Mildly reduced MTHFR activity - more relevant when combined with C677T. Ensure natural folate (leafy greens), B12 and B6.
AA (Variant)	Moderate	Reduced enzyme efficiency that can compound the C677T effect. Prioritise methylfolate, B12 and B6, and monitor homocysteine.

rs1801131 A1298C Population frequency: 30.0% Chr. 1 : 11,854,476

Second major MTHFR variant affecting BH4 synthesis

Genotype	Impact	What it means
AA (Normal)	Normal	Normal BH4 pathway function for neurotransmitter production.
AC (Carrier)	Low impact	Mildly reduced BH4 synthesis. May affect mood and neurotransmitter balance.
CC (Variant)	Moderate	Reduced BH4 synthesis. May benefit from SAMe or methylfolate supplementation.

rs1801133 C677T Population frequency: 35.0% Chr. 1 : 11,856,378

Most studied MTHFR variant affecting folate metabolism

Genotype	Impact	What it means
CC (Normal)	Normal	Normal folate metabolism. Your body efficiently converts folic acid to its active form.
CT (Carrier)	Moderate	Reduced MTHFR enzyme activity (60-70%). Consider methylfolate supplements and increase leafy green intake.
TT (Variant)	High impact	Significantly reduced MTHFR activity (30%). Methylfolate supplementation recommended. Avoid synthetic folic acid.