rs3745274 CYP2B6
CYP2B6*6 homozygous slow metabolizer. Increased efavirenz levels; higher risk of CNS side effects. Dose reduction recommended.
What is rs3745274?
rs3745274 is a single-nucleotide polymorphism (SNP) in the CYP2B6 gene (Cytochrome P450 2B6). Each person carries two copies, one from each parent, so a result is reported as a pair of letters such as TT. The table below describes what studies associate with each genotype; the association is statistical, across populations, and is not a diagnosis.
What does each rs3745274 genotype mean?
| Genotype | Association | What the evidence says | Confidence |
|---|---|---|---|
| TT | increased | CYP2B6*6 homozygous slow metabolizer. Increased efavirenz levels; higher risk of CNS side effects. Dose reduction recommended. | 88% |
| GT / TG | increased | CYP2B6*6 carrier. Intermediate metabolizer; monitor for efavirenz side effects. | 85% |
| GG | typical | Normal CYP2B6 metabolism. Standard efavirenz dosing. | 88% |
How common is the T allele of rs3745274?
Minor-allele frequency by population (gnomAD / 1000 Genomes):
| European | 26.0% |
|---|---|
| East Asian | 17.0% |
| African | 36.0% |
| South Asian | 28.0% |
| Admixed American | 25.0% |
| Global | 26.0% |
Which drugs have annotations for rs3745274?
PharmGKB clinical annotations (level 1A is the strongest evidence, 4 the weakest):
| Drug | Annotation type | Evidence level |
|---|---|---|
| efavirenz | Toxicity, Metabolism/PK, Dosage, Other, Efficacy | 1A |
| nevirapine | Toxicity, Metabolism/PK, Dosage, Other, Efficacy | 1A |
Is rs3745274 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 rs3745274 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.