rs1801133
rs1801133 is the MTHFR c.665C>T (Ala222Val, also called C677T) missense variant in methylenetetrahydrofolate reductase, the enzyme that converts 5,10-methylenetetrahydrofolate to 5-methyltetrahydrofolate for the folate and methionine cycles. The Val222 substitution makes the enzyme thermolabile and less active, with homozygous (TT) carriers retaining roughly 30% of normal activity and heterozygotes (CT) about 65%, which is associated with elevated homocysteine. It is used as inherited context for folate-pathway and homocysteine status, alongside MTHFR rs1801131.
Traits rs1801133 reads
Gene
Reference databases
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