Description of a family with a novel progressive myoclonus epilepsy and cognitive impairment.

We report a family of Algerian origin presenting an unusual, severe form of progressive myoclonus epilepsy characterized by myoclonus, generalized tonic-clonic seizures and moderate to severe cognitive impairment, with probable autosomal recessive inheritance. Disease onset was between 6 and 16 years of age. The diagnosis of Unverricht-Lundborg disease and all other known causes of progressive myoclonus epilepsies were excluded by specific laboratory tests and molecular analysis.