Genes for depression risk mapped in global study

The largest ever study into the genetics of depression has identified 44 gene variants that are linked to the disease. 

The unprecedented global collaboration used genetic information from over 135,000 people with depression and 344,000 controls. The team confirmed 14 gene variants that were previously identified, but also discovered 30 new variants, prompting hopes that further research may identify new drugs to treat depression. The study was published in Nature Genetics.

'The new genetic variants discovered have the potential to revitalise depression treatment by opening up avenues for the discovery of new and improved therapies,' says Dr Gerome Breen from the Institute of Psychiatry, Psychology and Neuroscience at King's College London. 'With this study, depression genetics has advanced to the forefront of genetic discovery.'

Although it has long been known that there is an important genetic component to depression, researchers have struggled to identify gene variants associated with the condition. One of the reasons for this, according to the new study, is that many gene variants contribute together to determine an individual's risk of developing depression.

'There is certainly no single gene for depression,' Professor Cathryn Lewis, also a researcher at the institute, told The Guardian. 'We know that thousands of genes are involved in depression with each having a very modest effect on a person's risk.'

The study team pooled together data from the UK, the USA, Iceland and Denmark to come up with the numbers to identify even those modest effects. It pooled data on genetics and depression from big databases such as UK Biobank and 23andMe. Some of the gene variants they have identified have been previously linked to other mental disorders such as schizophrenia, or have been linked to known risk factors for depression such as a high body mass index (BMI).

Some of the gene variants identified are linked to neurotransmitters such as serotonin, which are targeted by current drug therapies. The newly identified gene variants could lead to a better understanding of the biological mechanisms behind depression, and, with further research, new drug therapies.

'What we've had in recent decades is a shortage of new mechanisms that underlie depression and psychiatric disorders,' said Dr Breen. 'The hope is that in new data we identify new processes that can be targeted by newly developed types of drugs, which have different mechanisms of action to existing medications.'