PPT1 and neuronal ceroid lipofuscinosis: Individuals affected by an NCL have been described and studied throughout the world, especially in the Northern Hemisphere where most of the “classical” (CLN1, CLN2, CLN3, CLN4, and CLN10 diseases), as well as the “variant” NCLs (CLN5, CLN6, CLN7, CLN8, CLN11, CLN12, CLN13, and CLN14 diseases), were identified for the first time.