rs1801133(A;G)

1 copy of C677T allele of MTHFR = 65% efficiency in processing folic acid

Magnitude
2.2Worth knowing
Repute
Bad
Frequency
33%Average of 11 populations
On SNPedia
rs1801133(C;T)Minus strand
Gene
MTHFR

Frequency

Share of people with A;G in each HapMap population.

  • Mexican ancestry (Los Angeles)50%
  • Japanese (Tokyo)48%
  • Han Chinese (Beijing)47%
  • European ancestry (Utah)44%
  • Tuscan43%
  • Chinese (Denver)42%
  • Gujarati Indian29%
  • Yoruba (Nigeria)18%
  • Luhya (Kenya)17%
  • Maasai (Kenya)15%
  • African ancestry (Southwest US)11%

Other genotypes of rs1801133

  1. G;GGoodCommon genotype: normal homocysteine levelsTypical · 0.057% of people
  2. A;AMost notableBadhomozygous for C677T of MTHFR = 10-20% efficiency in processing folic acid = high homocysteine, low B12 and folate levelsWorth knowing · 2.810% of people

All about rs1801133

Notes

From SNPedia

It is found in approximately * 48% of Hispanic Americans * 45% of Caucasian Americans * 45% of Japanese * 37% of Germans * 29% of Asians * 24% of African Americans * 12% of Sub-Saharan Africans

Source and license

Adapted from rs1801133(C;T) on SNPedia, using a snapshot taken October 16, 2026. SNPedia content is shared under CC BY-NC-SA 3.0 US, and this page is shared under the same license.

SNPedia is a community-edited wiki. Its entries can be incomplete, out of date or wrong, and nothing here is a diagnosis or medical advice. Magnitude is a community rating of how interesting a genotype is, not a risk score.