The progressive myoclonic epilepsies are a rare group of debilitating epileptic encephalopathies characterized by myoclonic seizures, progressive neurological dysfunction and dementia. In the past year advances in gene mapping have isolated gene loci for the majority of progressive myoclonic disorders, paving the way for specific diagnosis, more accurate prognosis and risk calculation, as well as opening the potential for prenatal and pre-symptomatic diagnosis in at risk families.