Researchers at Baylor College of Medicine in Houston, Texas, report that when the gene SHANK3 is duplicated in mice, the animals exhibit a kind of hyperactivity that seems to correspond with a type of mania sometimes seen in patients with bipolar disorder that does not improve with typical treatment. The researchers found a couple of human patients who had similar duplications of SHANK3―one had been diagnosed as having bipolar disorder and the other was believed to have attention-deficit hyperactivity disorder. Neither patient had responded well to typical treatment.
As reported in a paper published on October 23rd in Nature, the researchers, including NARSAD Young Investigator Grantee, Hui-Chen Lu, Ph.D., note that for the first time it is possible to say that not just too little of SHANK3, but also too much expression of this gene influences brain function. It was previously known that when SHANK3 is mutated or missing, it plays a central role in some forms of autism spectrum disorder.
The researchers went on to report that the mood-stabilizing medication valproate, but not lithium, alleviated the manic-like behavior of the “Shank3 mice” (with the duplication). This work provides an explanation for those patients whose hyperactivity or mania does not get better with usual treatment. While it was suspected that there might be some underlying genetic difference in these patients, there is now something to test for that could lead to improvement in patient care.
Read an abstract of this research from Nature.