A genetic mutation in the gene KCNC1 that causes a rare form of epilepsy, known as progressive myoclonus epilepsy (PME), is reported in a paper published online this week in Nature Genetics. The discovery may aid in diagnosis and could eventually lead to better treatments.
PMEs are a group of rare, but particularly disabling, inherited seizure disorders. Anna-Elina Lehesjoki and colleagues sequenced the protein-coding portion of the genomes of 84 individuals with PME and screened for KCNC1 mutations in an additional 28 individuals. Of these, 16 patients shared the same mutation in KCNC1. This gene encodes a type of protein important in neuron function. Patients with the mutation all exhibited similar disease progression, beginning with muscle jerks at 6-14 years of age that became progressively worse, leading to disability in many cases. The patients also experienced occasional tonic-clonic (formerly known as grand mal) seizures.