Your DNA provides powerful clues to understanding disease, but genes aren't destiny--particularly when

it comes to mental illness. Researchers report that a particular gene may increase the risk of depression,

but only in combination with an added, nongenetic factor--a stressful life event.

The scientists found that people with one form of a protein that ferries serotonin, a mood-related

neurotransmitter, are especially prone to depression when faced with traumatic events, such as being

diagnosed with a medical illness or being a victim of childhood abuse. The version of the gene that these

individuals carry prevents nerve cells in the brain from reabsorbing serotonin, which leads to feelings of

sadness and negative mood and may make it harder for them to recover emotionally from a crisis.

The results confirm earlier work that had linked the serotonin-transporter gene to depression under

stressful circumstances, a connection that subsequent studies had questioned. The current analysis

includes a broader range of study data, however, and appears to confirm the association.