Genome-wide search finds genes linked to bipolar disorder

A new study, published in the journal Molecular Psychiatry, has identified new genes involved in bipolar disorder. The work may one day lead to better treatments for the disease.

None of the genes discovered by researchers from the US National Institutes of Health (NIH), in collaboration with others, are able to cause the disease independently. However, investigating the role that each plays in bipolar disorder may help scientists to understand why some patients respond differently to standard medications, helping them to develop more effective medications in the future.

'This research would not have been possible a very few years ago', says NIH Director Elias Zerhouni. 'We now have a new molecular target scientists can investigate in their search for better medications for bipolar disorder.'

Those affected by bipolar disorder (previously known as manic depression) have episodes of deep depression and manic behaviour, making it difficult to lead a normal life. Not all patients benefit from taking standard medications such as lithium or anti-depressants, so there is a strong need for better treatments to be developed.

One of the most strongly linked genes identified in this study, called DGKH, is thought to work in the same biochemical pathway as lithium, say the researchers. It is hoped that scientists may be able to develop improved drug treatments which work by controlling the amount of enzyme produced by this gene.

'Treatments that target just a few of these genes or the proteins they make could yield substantial benefits for patients. Lithium is still the primary treatment for bipolar disorder, but DGKH is a promising target for new treatments that might be more effective and better tolerated', said Francis McMahon, one of the researchers leading the study.

The researchers hope that, by studying how variation in these genes affects the workings of brain-cells, they will be able to develop new treatments for bipolar disorder tailored to an individual's genetic-makeup.

975 Americans took part in the study; 412 of which had bipolar disorder and 563 did not. New genetics technology allowed the researchers to pool the participant's DNA, rather than scan each participant's DNA separately, saving time and money. Those genes which occurred more frequently in the bipolar group were targeted for closer examination.

The researchers hope to extend their study to examine the genetic roots of bipolar disorder in other populations in order to find out if they share the same common genetic variations as Western populations.