rs242557

A SNP in the MAPT gene on chromosome 17. Its most notable genotype is A;G: normal

Gene
MAPT
Location
Chr 1745,942,346 (GRCh38)
Highest magnitude
0.0Typical
Tested on
23andMe, AncestryDNA, FamilyTreeDNA
Minor allele frequency
42%

Genotypes

As shown in 23andMe and AncestryDNA files.

  1. A;GMost notableNot ratednormalTypical · 0.046% of people
  2. G;GNot ratedNo summary available.Typical · 0.036% of people

On SNPedia: (A;G), (G;G). Magnitude rates how notable a genotype is from 0 to 10, not how risky it is.

Frequency

Share of each genotype in 11 HapMap populations.

  • AverageA;G 46% G;G 36%
  • European ancestry (Utah)A;G 58% G;G 30%
  • Han Chinese (Beijing)A;G 45% G;G 16%
  • Japanese (Tokyo)A;G 46% G;G 33%
  • Yoruba (Nigeria)A;G 47% G;G 42%
  • African ancestry (Southwest US)A;G 48% G;G 45%
  • Chinese (Denver)A;G 47% G;G 12%
  • Gujarati IndianA;G 46% G;G 37%
  • Luhya (Kenya)A;G 44% G;G 43%
  • Mexican ancestry (Los Angeles)A;G 39% G;G 45%
  • Maasai (Kenya)A;G 44% G;G 48%
  • TuscanA;G 39% G;G 48%

Conditions, medicines and genes

Other MAPT SNPs

All MAPT SNPs

Notes

From SNPedia

Notes

An initial case-control study of 300 patients with Alzheimer's disease found that subjects carrying both the rs2071746(T;T) and rs242557(A;A) genotypes had increased risk, however the confidence interval was huge (CI: 1.12-39.29; p = 0.037) and later studies have either failed to replicate the results or shown them to only partially hold in APOE4 carriers. Reports that they found only "nominally significant" association between Alzheimer's and rs242557 in ApoE4 positive individuals.

Source and license

Adapted from rs242557 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 Its entries can be incomplete, out of date or wrong, and nothing here is a diagnosis or medical advice.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.