Cytochrome P450 3A5
CYP3A5 is unusual: most people of European descent carry a non-functional variant and don't produce active enzyme at all. Most people of African descent do. For drugs like tacrolimus (used after organ transplant), this reverses the usual pharmacogenetic picture: the "normal" European phenotype is actually the poor metabolizer, while most African-descended patients are expressers who clear tacrolimus much faster and need higher doses.[1]
Gene2Rx reports your CYP3A5 genotype across 13 named star alleles, built from 8 variants curated by PharmVar.
Star alleles (like *1, *2, *4) are standardized names for distinct versions of a pharmacogene. *1 is the reference; higher numbers identify variants discovered later that change the enzyme's activity.
You inherit one allele from each parent, so your genotype is a pair (e.g. *1/*4). The pair determines your predicted phenotype — for example, whether you metabolize a drug at a normal, decreased, or no-function rate.
PharmVar is the international registry that defines and curates these allele names. Gene2Rx tests the variants required to call every CYP3A5 allele in the PharmVar catalog.
Gene2Rx covers 1 medication with published pharmacogenetic guidance for CYP3A5, drawn from CPIC and FDA sources. Each drug links to its full pharmacogenetics page.
These branded medications include at least one active ingredient whose metabolism or action involves CYP3A5. Each links to its full pharmacogenetic breakdown.
This page lists drugs affected by CYP3A5. A Gene2Rx report tells you which metabolizer group you fall into, and what that means for every medication on this list.
Get your report Look up a medicationInformational only, not medical advice. The presence of a CYP3A5 pharmacogenetic guideline does not mean every patient needs to change their dose. Never start, stop, or change a medication without talking to your prescribing clinician.