A genome-wide association study has revealed that genetic variation in the neurocan (NCAN) gene is significantly associated with bipolar disorder in thousands of patients. Importantly, in a follow-up study, these findings were replicated in tens of thousands of individual samples of bipolar disorder. 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. However, the authors caution that Ncan-deficient mice need to be re-examined for more subtle brain changes and behavioral abnormalities. "Our results provide strong evidence that genetic variation in the gene NCAN is a common risk factor for bipolar disorder," concluded Dr. Sven Cichon of the University of Bonn, one of the leaders of the study. "Further work is needed now to learn more about the biological processes that NCAN is involved in and how NCAN variants disturb neuronal processes in patients with bipolar disorder." The NCAN work was published online on February 24, 2011, in the American Journal of Human Genetics. [Press release] [AJHG abstract] Login Or Register To Read Full Story