rs17293443
A SNP in the SMAD3 gene on chromosome 15. Its most notable genotype is C;C: slightly higher odds of giving birth to fraternal twins
- Gene
- SMAD3
- Location
- Chr 1567,145,525 (GRCh38)
- Highest magnitude
- 1.5Minor
- Tested on
- 23andMe, AncestryDNA, FamilyTreeDNA
Genotypes
As shown in 23andMe and AncestryDNA files.
- C;CMost notableNot ratedslightly higher odds of giving birth to fraternal twins
- C;TNot ratedslightly higher odds of giving birth to fraternal twins
- T;TGoodcommon/normal
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 2% C;T 14% T;T 84%
- European ancestry (Utah)C;C 5% C;T 32% T;T 63%
- Han Chinese (Beijing)C;C 2% C;T 13% T;T 85%
- Japanese (Tokyo)C;C <1% C;T 7% T;T 92%
- Yoruba (Nigeria)C;C 0% C;T 7% T;T 93%
- African ancestry (Southwest US)C;C 0% C;T 5% T;T 95%
- Chinese (Denver)C;C 0% C;T 13% T;T 87%
- Gujarati IndianC;C 1% C;T 18% T;T 81%
- Luhya (Kenya)C;C 0% C;T 2% T;T 98%
- Mexican ancestry (Los Angeles)C;C 0% C;T 17% T;T 83%
- Maasai (Kenya)C;C <1% C;T 6% T;T 94%
- TuscanC;C 8% C;T 34% T;T 58%
Related
Other SMAD3 SNPs
- rs387906851C;TLoeys-Dietz SyndromeVery important
- rs387906852A;GLoeys-Dietz SyndromeVery important
- rs387906856G;TLoeys-Dietz SyndromeVery important
- rs587776880-;ATLoeys-Dietz SyndromeVery important
- rs587776881-;ALoeys-Dietz SyndromeVery important
- rs587776882-;GLoeys-Dietz SyndromeVery important
- rs730880215A;GLoeys-Dietz SyndromeVery important
- rs753486471A;CFamilial thoracic aortic aneurysms and dissections (FTAAD)Very important
Notes
From SNPedia
Notes
A meta-analysis found that the less common allele for this SNP, rs17293443(C), is actually associated with a slightly higher likelihood of giving birth to fraternal (dizygotic) twins (odds ratio 1.27, CI:1.19–1.35, p= 1.57 × 10e−8) compared to carriers of the (T) allele. A subsequent replication study of Icelanders yielded lower odds (1.15, CI:1.07–1.23,p=3 × 10e−4).
C;C
see discussion at rs17293443
C;T
see discussion at rs17293443
Source and license
Adapted from rs17293443 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 Its entries can be incomplete, out of date or wrong, and nothing here is a diagnosis or medical advice.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.