Cytochrome P450 2C9 Genotype, Varies

Casandra

Casandra Test Code MC42729Version 1 (DRAFT)

Performing Lab

Lab Mayo Clinic LabLab Test ID 2C9QTCPT Code 81227

Cytochrome P450 2C9 Genotype, Varies

Clinical Use

Use

Identifying individuals who may be at risk for altered metabolism of drugs that are modified by cytochrome P450 2C9. Primary metabolism of many drugs is performed by the cytochrome P450 (CYP) enzymes. The CYP2C9 enzyme participates in the metabolism of a wide variety of drugs, including warfarin and phenytoin. CYP2C9-mediated drug metabolism is variable among individuals due to genetic variants. These variants can lead to decreased enzyme activity, affecting drug metabolism rates and necessitating dosage adjustments to prevent adverse reactions.

Special Instructions

Saliva specimens are acceptable but not recommended due to lower DNA yield. If ordering for patients using warfarin, prefer using WARSQ / Warfarin Response Genotype which includes CYP2C9. Genetic testing consent required for New York. Orders not placed electronically need specific forms. Collect specimens according to kit instructions where applicable.

Limitations

Rare variants may result in false-negative or false-positive results. Samples from patients who received blood transfusions or stem cell transplants may not reflect the recipient's genotype accurately. It is not possible to detect all variants affecting CYP2C9 activity using this method. Results should be interpreted considering patient's drug metabolism, liver function, and other medications. Genetic results may not reflect patient's status if obtained post-liver transplantation.

Test Details

New York Approved