The genetic basis of bipolar disorder, a highly heritable mood disorder characterized by recurrent episodes of mania and depression is being studies anew by scientists.
The new study has identified a previously unrecognized susceptibility factor for bipolar disorder.
Sven Cichon, from the University of Bonn in Germany, together with his colleagues Markus M. Nothen (University of Bonn) and Marcella Rietschel (Central Institute of Mental Health, Mannheim) conducted the study.
The team led a Genome-wide association studies (GWAS) and a critical two-step follow-up study of samples from a great number of clinically well-characterized European, American, and Australian individuals with bipolar disorder.
They found that genetic variation in the gene neurocan (NCAN) showed a significant association with bipolar disorder in thousands of patients.
The researchers went on to show that the mouse version of this gene, which is written Ncan and is thought to be involved in neuronal adhesion and migration, is strongly expressed in brain areas associated with cognition and the regulation of emotions.
Although mice without functional Ncan did not exhibit obvious defects in brain structure or basic cell communication, there did appear to be some perturbation in mechanisms associated with learning and memory, mechanisms that have been associated with the cognitive deficits observed in bipolar disorder.
"Our results provide strong evidence that genetic variation in the gene NCAN is a common risk factor for bipolar disorder," concluded Cichon.
The study was published online by Cell Press February 24 in the American Journal of Human Genetics.