Saturday, December 22, 2007

Not Yet: CDC panel questions antidepressant gene test

About half of all depressed people who take standard antidepressant drugs fail to improve. Some suffer unpleasant side effects and abandon the medicines, while others simply don't feel better. Commercial tests claim to predict, by a genetic analysis, how well individual patients will fare on different antidepressants, but a panel convened by the Centers for Disease Control and Prevention (CDC) in Atlanta now says that the tests don't work as advertised.

The panel "discourages" use of such tests until further studies clarify their value, according to a statement the group published in the December Genetics in Medicine.

"That isn't to say that eventually there won't be a role for these tests. We just don't know what that role is yet," says panel member Joan Scott of the Genetics and Public Policy Center in Washington, D.C.

The tests scan a person's DNA for variations in genes for two key liver enzymes. These enzymes break down selective serotonin reuptake inhibitors (SSRIs), a standard class of antidepressants that includes fluoxetine (Prozac) and nearly a dozen other drugs. Variations in the two enzymes affect how quickly different people clear SSRIs from their blood, which in turn influences the drugs' effectiveness.

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