Genetic tests on depressed people who tried to take their own lives have revealed a DNA marker that could help doctors spot patients who are at risk of suicide

The gene variant was more common in depressed people who had attempted suicide than in those who had not, suggesting that it marks out a group of people who are especially vulnerable if they become depressed. The gene is among several that might ultimately be used to screen people with serious depression to identify those that need the closest supervision while being treated. Previous studies of twins and people who were adopted show that around half a person's risk of suicide is due to genetic factors. The heritability of suicidal tendencies can explain tragic clusters of deaths in families, such as those that blighted Ernest Hemingway's and Kurt Cobain's families. Despite clear evidence that suicidal behavior can run in families, scientists have struggled to find which genes are involved. Part of the difficulty has been distinguishing gene variants for suicide risk from those that put people at risk of depression. Researchers conducted genetic tests on 412 Caucasians with major depression, 154 of whom had attempted suicide. The results revealed a variant of a gene called RGS2 that appeared more often in those who tried to kill themselves. The gene affects how strongly receptors in the body respond to chemicals released by nerve cells. Researchers found that 43% of the depressed patients who had attempted suicide had two copies of a particular variant of the RGS2 gene, while fewer than a fifth of them had two copies of a safer variant of the gene.