CYP1A2 is a gene that provides instructions for making an enzyme involved in the metabolism of various substances in the body, including drugs and environmental chemicals. This enzyme is part of the cytochrome P450 family, which plays a crucial role in breaking down compounds, making them easier for the body to eliminate. The activity of CYP1A2 can be influenced by factors such as diet, lifestyle, and certain medications. For example, substances like caffeine and smoking can increase the enzyme's activity, while others may inhibit it. Understanding CYP1A2 is important for personalized medicine, as it affects how individuals respond to various treatments.