24 June 2013. Many genes have come to the attention of mental illness researchers because tiny variations in them appear to ever so slightly increase the risk of mental illness. But one gene, dubbed DISC1, receives the lion's share of attention, and for good reason. Having a rare break in the gene virtually guarantees a major mental illness. Originally dubbed "disrupted in schizophrenia 1" because most of the handful of cases were schizophrenia, it's now clear that a break in DISC1 can also lead to other serious mental illnesses such as bipolar disorder or depression.
In a new genetic study led by W. Richard McCombie of Cold Spring Harbor Laboratory in New York and David Porteous of the University of Edinburgh, U.K., researchers have started the mammoth task of combing through the very long chain of molecules—more than 500,000—that makes up DISC1. The study, which was published June 4, 2013, in Molecular Psychiatry, provides the most complete look at the DISC1 gene to date.
The researchers examined the DNA sequence of DISC1 in over 1,500 subjects and catalogued nearly 3,000 minute differences in links of the molecular chain. The majority were very rare, present in less than 1 percent of subjects. Less than half of the total variants found in the current study had been identified in previous genetic studies, and the researchers estimate that at least 40 percent of the rare molecular variations that exist have yet to be discovered. The hope is that further excavation of this gene will help scientists understand how breaking it leads to mental illness. (For more details on this study, see SRF related news story.)—Allison A. Curley.