CSTB and Unverricht-Lundborg disease: Biallelic partial loss-of-function mutations in the CSTB gene (Pennacchio et al., 1996) underlie Unverricht-Lundborg disease (progressive myoclonus epilepsy type 1, EPM1; OMIM 254800), a neurodegenerative disorder that usually manifests during late childhood or early adolescence (Lehesjoki and Kälviäinen, 2020).