Rapidly progressive phenotype of Lafora disease associated with a novel NHLRC1 mutation.

Lafora disease is a fatal, autosomal recessive form of progressive myoclonus epilepsy. Patients characteristically exhibit myoclonic and tonic-clonic seizures and cognitive impairment, beginning in their second decade. Alterations in two genes were identified as the cause of the disease. Mutations in the NHL repeat containing 1 (NHLRC1) gene were described in association with a more benign clinical course and later age of death, compared with epilepsy progressive myoclonus type 2A (EPM2A) mutations. We describe a rapidly progressive phenotype of Lafora disease in an adolescent patient with a novel NHLRC1 mutation. He developed severe disability and dementia less than 2 years after the onset of signs.