rs1799853 CYP2C9
CYP2C9*2 carrier. Reduced metabolism of warfarin, NSAIDs, and phenytoin; lower dose may be needed.
What is rs1799853?
rs1799853 is a single-nucleotide polymorphism (SNP) in the CYP2C9 gene (Cytochrome P450 2C9). Each person carries two copies, one from each parent, so a result is reported as a pair of letters such as CT. The table below describes what studies associate with each genotype; the association is statistical, across populations, and is not a diagnosis.
What does each rs1799853 genotype mean?
| Genotype | Association | What the evidence says | Confidence |
|---|---|---|---|
| CT / TC | reduced | CYP2C9*2 carrier. Reduced metabolism of warfarin, NSAIDs, and phenytoin; lower dose may be needed. | 90% |
| TT | reduced | CYP2C9*2 homozygous. Significantly reduced drug metabolism. | 93% |
| CC | typical | Normal CYP2C9*2 function. Standard warfarin metabolism. | 92% |
How common is the T allele of rs1799853?
Minor-allele frequency by population (gnomAD / 1000 Genomes):
| European | 12.0% |
|---|---|
| East Asian | 0.1% |
| African | 2.0% |
| South Asian | 5.0% |
| Admixed American | 7.0% |
| Global | 6.0% |
Which drugs have annotations for rs1799853?
PharmGKB clinical annotations (level 1A is the strongest evidence, 4 the weakest):
| Drug | Annotation type | Evidence level |
|---|---|---|
| hormonal contraceptives for systemic use | Toxicity, Efficacy, Metabolism/PK, Dosage | 3 |
| irbesartan | Toxicity, Efficacy, Metabolism/PK, Dosage | 3 |
| busulfan | Toxicity, Efficacy | 3 |
Is rs1799853 on 23andMe and AncestryDNA chips?
Yes — it is genotyped directly on 23andMe V3, 23andMe V4, 23andMe V5, AncestryDNA V1, AncestryDNA V2. Orviva reads it from a raw-data export without imputation.
Sources
Upload your 23andMe, AncestryDNA or WeGene raw file → · Ask G2: “What is my genotype at rs1799853 and what does it mean for me?”
Genetic associations describe risk across populations, not a diagnosis for any one person. Most variants shift risk modestly and act alongside lifestyle, environment and other genes. Consumer DNA chips do not read every position and can be wrong at any single one. For general education only; talk to a clinician or genetic counsellor before acting on anything here, and never change a prescribed medicine without your prescriber.