Gene CYP3A5
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Also known as
CP35, P450PCN3, PCN3, cytochrome P450 family 3 subfamily A member 5Overview
CYP3A5 (Cytochrome P450 Family 3 Subfamily A Member 5) encodes an enzyme that metabolizes many of the same drugs as CYP3A4, including immunosuppressants (tacrolimus, cyclosporine), certain statins, calcium channel blockers, and HIV protease inhibitors. Unlike CYP3A4, CYP3A5 shows a striking on/off expression pattern determined by genetics.The CYP3A5*3 allele creates a splice defect that prevents protein production. Most Caucasians and Asians are homozygous for this non-functional allele, while most Africans carry at least one functional CYP3A5*1 allele. Individuals who express CYP3A5 (CYP3A5*1 carriers) metabolize tacrolimus faster and require significantly higher doses to achieve therapeutic levels after organ transplantation.
Understanding your CYP3A5 genetic status is clinically important for tacrolimus dosing in transplant recipients. CPIC guidelines recommend higher starting doses for CYP3A5 expressers. This pharmacogenetic test is increasingly used in transplant centers to optimize initial immunosuppressant dosing.