rs4646
A SNP in the CYP19A1 gene on chromosome 15. Its most notable genotype is A;A: common in clinvar
- Gene
- CYP19A1
- Location
- Chr 1551,210,647 (GRCh38)
- Highest magnitude
- 0.0Typical
- Tested on
- 23andMe, AncestryDNA, FamilyTreeDNA
- Minor allele frequency
- 32%
Genotypes
As shown in 23andMe and AncestryDNA files.
On SNPedia: (A;A), (C;C). 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;A 10% C;C 46%
- European ancestry (Utah)A;A 4% C;C 58%
- Han Chinese (Beijing)A;A 10% C;C 50%
- Japanese (Tokyo)A;A 6% C;C 54%
- Yoruba (Nigeria)A;A 10% C;C 40%
- African ancestry (Southwest US)A;A 7% C;C 46%
- Chinese (Denver)A;A 11% C;C 41%
- Gujarati IndianA;A 16% C;C 33%
- Luhya (Kenya)A;A 8% C;C 47%
- Mexican ancestry (Los Angeles)A;A 21% C;C 28%
- Maasai (Kenya)A;A 6% C;C 49%
- TuscanA;A 12% C;C 60%
Related
Conditions, medicines and genes
Other CYP19A1 SNPs
- rs78310315C;TUnaffected carrier of an aromatase deficiency mutationImportant
- rs10046G;Gcommon in clinvarTypical
- rs700518T;Tcommon in clinvarTypical
- rs700519G;Gcommon in complete genomicsTypical
- rs1062033C;Gincreases susceptibility to postmenopausal osteoporosisTypical
- rs1902584A;Acommon in complete genomicsTypical
- rs1961177C;Ccommon in complete genomicsTypical
- rs2899472C;Ccommon on affy axiom dataTypical
Notes
From SNPedia
Show notes, about 170 words
rs4646 is a SNP in the CYP19A1 gene on chromosome 15. The CYP19A1 gene is probably the primary one studied to date as possibly associated with the efficacy or toxicity of aromatase inhibitors such as letrozole, anastrozole and exemestane. The effect of CYP19A1 variant in response to such inhibitors has produced conflicting results in studies (see citations below), and although rs4646 may be perhaps the best studied CYP19A1 variant, there is to date no robust or replicated conclusion about it with respect to aromatase inhibitor response. rs4646(A) allele carriers with breast cancer being treated with letrozole are reported to do worse than rs4646(C;C) patients, based on a study of (only) 95 women. Based on a meta-analysis of (only) two studies, one involving treatement with letrozole and the other anastrozole, rs4646(A) allele carriers with metastatic breast cancer showed a greater time to progression (TTP) compared to rs4646(C;C) patients, indicating overall a possible benefit to being an (A) allele carrier.
Source and license
Adapted from rs4646 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.