The group of disorders known as the neuronal ceroid lipofuscinoses have common features including a variable age of onset, motor and mental decline, epilepsy, and visual loss. Common symptoms together with the presence of abnormal lysosomal storage in neurons and other cells define the condition. Collectively the NCLs are important as one of the causes of childhood neurodegenerative diseases. Based on the clinical presentations different types have been described in the medical literature, such as the late infantile NCL type 2, Jansky–Bielschowsky disease and the juvenile NCL type 3 Batten disease. Most NCLs are autosomal recessively inherited. Mutations in at least eight genes (PPT1/CLN1, TPP1/CLN2, CLN3, CLN5, CLN6, MFSD8/CLN7, CLN8) have been identified. The prevalence around 0.5–8 per 100,000 live births varying per region.