English and Danish scientists have identified a new gene linked to both depression and bipolar disorder. The team investigated bipolar cases in families from UK and in Denmark, and then at large numbers of unrelated people with bipolar disorder.

They identified the gene, named Slynar, on chromosome 12. Bipolar disorder is known to be strongly hereditary but the Slynar gene is just one of the three genes known to be involved in the disorder. It is present in around 10 % of bipolar disorder cases.

It was already known that there are multiple genetic subtypes of the disorder. That's why progress in identifying the exact genes responsible has been slow because groups of families inherit different susceptibility genes.

The Slynar gene is normally found in the genoma, but its mutations provoke bipolar disorder. Scientists do not yet know what the gene's normal function is or what is the effect of these genes in provoking the disorder.

Hugh Gurling of UCL says: "The next step is to determine the role of the Slynar gene in the brain and how abnormalities in this gene may cause bipolar disorder. Using techniques such as animal models will help us to fully understand the mechanisms behind this gene and explore how we might be able to intervene in these mechanisms, to help people with the disorder."

"We hope our discovery will eventually lead to new treatments for depression and bipolar disorder, including possible preventive strategies, for example with drugs or even through nutritional intervention."

Around 0.5 % of the British population develops bipolar and related mood disorders.

Depression include losing weight, negative feeling about oneself, feeling of hopelessness about the future and sometimes ending up in a depressive immobility in bed, unable to eat, drink or talk.

Bipolar disorder, also known as maniac depression, experiments extreme mood highs, overactivity, increased libido, sleeplessness and grandiose delusions.