CYP3A4 (Cytochrome P450 Family 3 Subfamily A Member 4): CYP3A4 is one of the most important enzymes in drug metabolism, involved in breaking down a wide range of medications, including statins, immunosuppressants, benzodiazepines, and certain chemotherapy drugs. Genetic variations in CYP3A4 can influence drug clearance, affecting both efficacy and the risk of side effects. Testing CYP3A4 can help guide medication dosing for safer and more effective treatment.