Progressive myoclonus epilepsy
Progressive Myoclonic Epilepsies (PME) are a rare group of inherited neurodegenerative diseases characterized by myoclonus, resistance to treatment, and neurological deterioration. The cause of PME depends largely on the type of PME. Most PMEs are caused by autosomal dominant or recessive and mitochondrial mutations.
Source: Wikipedia — Progressive myoclonus epilepsy (CC BY-SA 4.0)