Lafora disease is an inherited, severe form of progressive myoclonus epilepsy. The condition most commonly begins with epileptic seizures in late childhood or adolescence. Other signs and symptoms include difficulty walking, muscle spasms (myoclonus) and dementia. Affected people also experience rapid cognitive deterioration that begins around the same time as the seizures. Most cases are caused by changes in either the EPM2A gene or the NHLRC1 gene and are inherited in an autosomal recessive manner.