rs12953717

A SNP in the SMAD7 gene on chromosome 18. Its most notable genotype is C;C: 1.37x increased risk for colorectal cancer

Gene
SMAD7
Location
Chr 1848,927,559 (GRCh38)
Highest magnitude
0.0Typical
Tested on
23andMe, AncestryDNA, FamilyTreeDNA
Minor allele frequency
33%

Genotypes

As shown in 23andMe and AncestryDNA files.

  1. C;CMost notableNot rated1.37x increased risk for colorectal cancerTypical · 0.053% of people
  2. C;TNot rated1.11x increased risk for colorectal cancerTypical · 0.037% of people
  3. T;TBad1x normal risk for colorectal cancerTypical · 0.010% of people

On SNPedia: (C;C), (C;T), (T;T). 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.

  • AverageC;C 53% C;T 37% T;T 10%
  • European ancestry (Utah)C;C 40% C;T 45% T;T 15%
  • Han Chinese (Beijing)C;C 58% C;T 36% T;T 6%
  • Japanese (Tokyo)C;C 71% C;T 26% T;T 4%
  • Yoruba (Nigeria)C;C 57% C;T 35% T;T 8%
  • African ancestry (Southwest US)C;C 60% C;T 33% T;T 7%
  • Chinese (Denver)C;C 50% C;T 39% T;T 11%
  • Gujarati IndianC;C 47% C;T 45% T;T 9%
  • Luhya (Kenya)C;C 73% C;T 26% T;T <1%
  • Mexican ancestry (Los Angeles)C;C 43% C;T 47% T;T 10%
  • Maasai (Kenya)C;C 65% C;T 30% T;T 6%
  • TuscanC;C 22% C;T 47% T;T 31%

Conditions, medicines and genes

Other SMAD7 SNPs

All SMAD7 SNPs

Notes

From SNPedia

Notes

rs12953717 is one of 3 SNPs in the SMAD7 gene associated with risk for colorectal cancer, based on a large study (7,400+ cases) conducted in the UK. The odds ratios show an increased risk for the minor rs12953717(T) allele; the OR for (T;T) homozygotes is 1.37 (CI: 1.25-1.5), and for (C;T) heterozygotes 1.11 (CI: 1.03-1.2), overall p=9x10 -12 .

Source and license

Adapted from rs12953717 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 Its entries can be incomplete, out of date or wrong, and nothing here is a diagnosis or medical advice.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.