Depression

The Cytochrome P450 Genetic Test

Over the past decade, the study of human genetics has shown how genetic factors influence a person's response to drugs and their possible side effects. Mayo Clinic psychiatrists, in partnership with laboratory medicine specialists, have developed a test (the cytochrome P450 test) that helps pinpoint genetic factors that play a role in a person's response to various drugs, including most antidepressant medications. The cytochrome P450 test represents a major advance in the ability to provide the best care possible for depression.

The cytochrome P450 test is a blood test that provides information about how a person's body metabolizes (breaks down) drugs. Genes are contained in each of the body's cells. Genes instruct the body to produce proteins that control how cells grow and function. The cytochrome P450 test identifies the gene or genes responsible for producing enzymes which metabolize these drugs.

One person may metabolize an antidepressant slowly. This can cause side effects or even a toxic reaction — which might lead the person to stop taking the drug. Other people may metabolize the drug quickly, eliminating the drug from the body before they benefit from it.

The cytochrome P450 test gives the doctor information to help choose the right antidepressant and the correct dose to reduce side effects.