Unverricht-Lundborg disease (ULD) is a rare inherited form of epilepsy, it is the purest and least severe form of progressive myoclonus epilepsy (PME), and it is not correlated with progressive cognitive deficit. The disorder symptoms stabilizes in adulthood, with a changeable degree of permanent, often severe, handicap as a result of myoclonus. The disease age of onset ranges between 6 to 15 years and the clinical symptoms include tonic-clonic or clonic-tonic-clonic seizures, episodes of myoclonus (massive or segmental), loss of consciousness, photosensitivity, muscle rigidity, and often ataxia. Episodes of myoclonus occur due to stress, light, physical exertion, or other stimuli. Myoclonic episodes may evolve within 5 to 10 years to a severe form that can obstruct walking and further daily activities. ULD patients may develop ataxia, intentional tremor, dysarthria, and a slow and mild decline in intellectual functioning.
Global prevalence of ULD differs and is found to be the highest in regions with a higher degree of consanguinity such as in Maghreb countries and in specific geographic isolates such as Finland and Reunion Island. ULD is diagnosed through family history, age at onset, the geographical and ethnic context, and by the classic traits of myoclonus and epilepsy, in the case of cognitive and sensory deficits absence. Meanwhile, diagnosis of ULD in patients can be confirmed through molecular biology. Genetic counseling and prenatal diagnosis can be carried out, though they are rarely performed if mutations are found. Particular aspects of ULD still remain vague despite of intensive research and it remains as a quasi "idiopathic" type of progressive myoclonic epilepsy.
