TPP1 and epilepsy: CLN2 disease (MIM# 204500) classically presents with seizure onset at 2–4 years of age, preceded by delayed language development, and followed by rapidly progressing dementia, psychomotor decline (loss of the ability to walk and talk), epilepsy, blindness, and death, typically between 6 years of age and the early teenage years (Mole et al., 2018; Mole, 2001; Nickel et al., 2016; Nickel et al., 2018; Steinfeld et al., 2002).