CSTB and Myoclonus: Dodecamer (CCCCGCCCCGCG) expansions in the 5′UTR of CSTB (cystatin-B, MIM #601145) are responsible for progressive myoclonic epilepsy type 1 (EPM1, also known as Unverricht–Lundborg disease, MIM #254800), a recessive neurodegenerative epileptic condition characterized by tonic-clonic seizures and myoclonus [34].