Researchers have identified a genetic variation that increases a person’s susceptibility to developing bipolar disorder, a disorder that is highly heritable.
The research, published in the American Journal of Human Genetics, is based on a relatively new technique for the study of the genetics of bipolar disorder.
The innovation, termed genome-wide association studies (GWAS) is a method to systematically sort through all the DNA of many individuals in order to identify genetic variations associated with a particular disease.
GWAS has been used to study type II diabetes, Crohn disease, and schizophrenia.
German researchers led a 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.
Dr. Sven Cichon, from the University of Bonn, and his colleagues found that genetic variation in the gene neurocan (NCAN) showed a significant association 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 disturbance inÂ 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,” saidÂ Cichon. “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.”
Source: Cell Press