Gene Hunters Find Cause of Rare Movement Disorder

After a challenging two-decade hunt, scientists have pinpointed the gene responsible for a rare disease that causes seizures in infancy and sudden, uncontrollable movements in adolescence and early adulthood.The findings, published December 15, 2011, in Cell Reports, could pave the way to new therapies for more common forms of seizures and dyskinesias, or abnormal movements, the researchers say."There are a lot of dyskinesias for which we don't have good treatments and they are a big problem, such as in Huntington's disease and Parkinson's disease," says Howard Hughes Medical Institute investigator Louis Ptáček, professor of neurology at the University of California San Francisco, who led the new study. "If we can understand the pathways in the brain that regulate dyskinesia, then it's my hope that we’ll be able to target better drugs."Ptáček's interest in dyskinesia dates to 1985 when, as a third-year medical student at the University of Wisconsin, Madison, he met a 16-year-old boy who was having bizarre spasms. Every time the boy switched from one movement to another, like from sitting to standing or walking to running, his limbs would inexplicably flail or twist, as if performing an odd dance."Nobody knew what the heck was going on," Ptáček recalls.One night around 2 a.m., after scouring the library's medical databases, Ptáček figured out the diagnosis: paroxysmal kinesigenic dyskinesia, or PKD, which had been reported in just a handful of other cases. He knew from those papers that PKD could be treated with a low dose of a common anticonvulsant medication. When doctors gave the boy the drug, carbamazepine, he quickly improved."He had been having attacks hundreds of times per day. A few weeks after treatment, he was essentially having zero attacks," Ptáček says. "It felt so satisfying to have gotten it right."Read more at...HHMI News, December 2011.