Australian researchers are reported to have identified a gene which gives rise to bipolar disorder in human beings. Other teams have previously claimed to have found bipolar susceptibility genes, but this is the first time that the evidence has been close to conclusive, according to the researchers.
The work might also explain how lithium, which has been prescribed for bipolar sufferers for more than 30 years, can help patients. But while lithium works for some, one-third to one-half of patients do not benefit from existing treatments, none of which were created specifically for the disorder, which is characterized by extreme mood states.
"The long term goal is to get new drug targets that are specific for bipolar disorder," says team member Ian Blair of the Garvan Institute of Medical Research in Sydney.
The new study of about 1,200 patients from Australia, the UK and Bulgaria implicates a gene called Fat on chromosome four. This gene plays a role in cell adhesion in the brain. People with the newly identified polymorphism, or form of this gene, appear to be at twice the risk of developing bipolar disorder, though it is not yet clear exactly why, says Blair.
More work is also needed to reveal exactly which other genes might be involved. "This is a complex genetic disorder caused by the interaction of a number of genes and the environment," Blair said.