rs1799966
A SNP in the BRCA1 gene on chromosome 17. Its most notable genotype is C;C: very slightly increased risk for breast cancer
- Gene
- BRCA1
- Location
- Chr 1743,071,077 (GRCh38)
- Highest magnitude
- 2.0Worth knowing
- Tested on
- 23andMe, AncestryDNA, FamilyTreeDNA
- Minor allele frequency
- 33%
Genotypes
Plus strand, as in 23andMe and AncestryDNA files.
- T;TGoodcommon in clinvar
- C;TBadvery slightly increased breast cancer risk
- C;CMost notableBadvery slightly increased risk for breast cancer
SNPedia records rs1799966 on the minus strand: (A;A), (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.
- AverageT;T 48% C;T 43% C;C 9%
- European ancestry (Utah)T;T 46% C;T 46% C;C 8%
- Han Chinese (Beijing)T;T 46% C;T 42% C;C 12%
- Japanese (Tokyo)T;T 53% C;T 39% C;C 8%
- Yoruba (Nigeria)T;T 63% C;T 35% C;C 1%
- African ancestry (Southwest US)T;T 51% C;T 46% C;C 4%
- Chinese (Denver)T;T 29% C;T 55% C;C 16%
- Gujarati IndianT;T 32% C;T 50% C;C 18%
- Luhya (Kenya)T;T 63% C;T 33% C;C 5%
- Mexican ancestry (Los Angeles)T;T 41% C;T 43% C;C 16%
- Maasai (Kenya)T;T 61% C;T 36% C;C 3%
- TuscanT;T 41% C;T 52% C;C 7%
Related
Conditions, medicines and genes
Other BRCA1 SNPs
- rs28897696T;Tcarrier of two copies of BRCA1 variant; likely to be at high risk for breast/ovarian cancerVery important
- rs41286296A;CBRCA1 pathogenic mutation associated with breast cancerVery important
- rs62625306A;CBRCA1 pathogenic mutation associated with breast cancerVery important
- rs62625307A;GBRCA1 pathogenic mutation associated with breast cancerVery important
- i6051899A;Clikely to be BRCA1 variant pathogenic for breast cancerVery important
- rs1800747C;TBRCA1 pathogenic mutation associated with breast cancerVery important
- rs28897672A;Tconsidered a pathogenic BRCA1 breast cancer variantVery important
- rs28897686A;CBRCA1 pathogenic mutation associated with breast cancerVery important
Notes
From SNPedia
Notes
This SNP, a variant in the BRCA1 gene, is 1 of 25 SNPs reported to represent independently minor, but cumulatively significant, increased risk for breast cancer. For details of all 25 SNPs in this group, along with the two methods used to calculate overall risk estimates for breast cancer, refer to the SNPedia breast cancer entry. For this particular SNP, the risk (minor) allele is (G).
Source and license
Adapted from rs1799966 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.