Sensitive

CYP3A5 expression (*3 allele)

CYP3A5 · rs776746

Where this position leads

Solid lines are connections this site curates. Dashed lines mean the two ends share a research paper — worth knowing, and not a claim that one explains the other.

What ClinVar records

Classification Benign for Lung cancer, Ovarian cancer, Familial pancreatic carcinoma, Gastric cancer, Nonpapillary renal cell carcinoma and 2 more; criteria provided, multiple submitters, no conflicts (2 of 4 stars, 3 submitters), last evaluated 2018-03-14. ClinVar record 226021 NM_000777.5(CYP3A5):c.219-237=

Classification association; drug response; risk factor for Hypertension, salt-sensitive essential, susceptibility to, refractory myasthenia gravis, Tacrolimus response; no assertion criteria provided (0 of 4 stars, 4 submitters), last evaluated 2022-04-15. ClinVar record 5066 NM_000777.5(CYP3A5):c.219-237A>G

What this is ClinVar's aggregate record for this position (as of its 2026-10-19 release), not a result about you. A classification describes the variant against the condition named, as laboratories submitted it. Whether a person carries this variant, and what that would mean for them, is a question for a clinical test and a genetic counsellor.

What each result means

C/C Two copies of *3. The variant creates a splice site that should not be there, so the protein made from it is truncated and does not work. This is a CYP3A5 non-expresser, and it is the majority genotype in people of European and East Asian ancestry — which is why the standard tacrolimus starting dose is the one that suits this genotype. Nothing here needs adjusting.

C/T One functional copy and one *3. Still an expresser — a single working copy is enough to produce the enzyme — and the same increased tacrolimus starting dose applies. The most common way to be an expresser in a population where *3 is frequent.

T/T Two copies of *1, the functional allele. This is a CYP3A5 expresser: the enzyme is made and works. For tacrolimus after a transplant, an expresser typically needs about 1.5 to 2 times the standard starting dose to reach the same blood level, and CPIC recommends starting higher rather than discovering it through repeated low readings. This genotype is the majority in much of sub-Saharan Africa and uncommon in Europe.

This affects the dose needed, not the target. The blood level a transplant team aims for is the same whatever the genotype; what differs is how much drug it takes to get there. Dosing after a transplant is measured directly and adjusted by the team, and nothing in a raw data file should change a dose without them.

Source

Clinical Pharmacogenetics Implementation Consortium (CPIC) Guidelines for CYP3A5 Genotype and Tacrolimus Dosing

Birdwell KA, Decker B, Barbarino JM, Peterson JF, Stein CM, Sadee W, Wang D, Vinks AA, He Y, Swen JJ, Leeder JS, van Schaik R

and 4 more — show all

Thummel KE, Klein TE, Caudle KE, MacPhee IA

Clinical pharmacology and therapeutics · 2015 · PMID 25801146

What people read about alongside this

Heart and circulation15 Kidneys13 Cholesterol and blood fats4 Blood sugar and insulin2 Liver2 Natural selection1 Learning and focus1 Bones and fractures1 Skin, sun and hair1

Papers in Europe PMC whose title or abstract names both this rsID and that subject. A shared paper means somebody wrote about the two together — it is not a claim that this position explains the subject.

Questions about rs776746

What is rs776746?

rs776746 is a single position in the genome, in or near the CYP3A5 gene. Published research associates it with cyp3a5 expression (*3 allele). A single variant does not decide an outcome — it shifts a probability, and for most common variants the shift is small.

What conditions is rs776746 linked to?

On MyGeneLog this position is linked to CYP3A5 Metaboliser Status. The research behind each link, and its sources, are set out on that condition page.

Does rs776746 affect how medicines work?

CYP3A5 carries pharmacogenomic findings for Tacrolimus. That is educational information, not a prescription or a dosing guide. Any decision to start, stop or change a medicine belongs with the clinician or pharmacist managing your treatment.

What do people read about alongside rs776746?

Subjects that appear in the title or abstract of the same papers as this rsID include heart and circulation (15 papers), kidneys (13 papers), cholesterol and blood fats (4 papers), blood sugar and insulin (2 papers), liver (2 papers). A shared paper means somebody wrote about the two together; it is not a claim that this position explains the topic.

Does having rs776746 mean I will get this?

No. Common variants like this one move a probability slightly and, on their own, rarely decide anything about one person. Nothing on this page is a diagnosis, and health decisions should be made with a clinician who can see your whole picture.

Where does the information about rs776746 come from?

CPIC Guideline for CYP3A5 Genotype and Tacrolimus Dosing (Clin Pharmacol Ther 2015, PMID 25801146). Every variant on MyGeneLog comes from public primary sources and is published with its citation and the date it was checked.

Quoting this page

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CYP3A5 expression (*3 allele) (rs776746). MyGeneLog™. https://www.mygenelog.com/variants/rs776746

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