The neuronal ceroid-lipofuscinoses are a group of inherited, neurodegenerative, lysosomal storage disorders that are associated with mutations in at least eight genes. Mutations in the TPP1 (CLN2) gene are most commonly associated with the classic late-infantile neuronal ceroid-lipofuscinosis (LINCL) form that is characterized by onset of symptoms between 2 and 4 years. Epilepsy is typically the presenting symptom followed by regression of developmental milestones; speech delay, slow learning, intellectual disability, dementia, and neuromotor dysfunction including ataxia and the inability to walk are characteristic. Visual impairment typically appears at age 4 to 6 years, with rapid progression to blindness. Life expectancy ranges from 6 years to older than 40 years. Some patients with mutations in the TPP1 gene have been reported with juvenile neuronal ceroid-lipofuscinosis (JNCL) presentation that is characterized by later onset with the presenting symptom being visual impairment, followed by epilepsy. As a group the neuronal ceroid-lipofuscinoses are the most common hereditary progressive neurodegenerative disease with an incidence ranging from 1 to 7 per 100,000 births.