A single variation in a gene controlling the transport of the neurotransmitter serotonin, combined with exposure to threatening life events, led to clinical depression in their patient sample.

Other variations of the gene, combined with the same life events, did not lead to depression.

Professors Jorge Cervilla Ballesteros, Blanca Gutiérrez Martínez and colleagues at the University of Granada said the most important consequence of their research is that scientists might soon be able to predict a person’s response to antidepressants by taking into account the individual’s genotype.

That might allow researchers to design drugs according to each person’s genetic configuration and their exposure to environmental factors.

The research was recently published in the journal Molecular Psychiatry.