Topical Review The Neuronal Ceroid-Lipofuscinoses

The neuronal ceroid-lipofuscinoses, a group of progressive neurodegenerative diseases in children and in adults, have now been recognized for some 90 years, and the childhood forms represent one of the largest groups of progressive neu-rodegenerative diseases in children. Apart from a core group of major clinical forms—the infantile, the late-infantile, the juvenile, and the adult forms—numerous atypical patients afflicted with neuronal ceroid-lipofuscinosis have now been identified, constituting 10 % to 20 % of all patients with neuronal ceroid-lipofuscinosis. These "atypical " patients have, over the past 10 years, prompted the suggestion of 15 atypical variants or minor syndromes, many of them displaying the lipopigments of classic curvilinear and fingerprint ultrastructure, but others displaying granular osmiophilic deposits. The former lipopigments contain the subunit C of the mitochondrial adenosine triphosphate synthase, but lipopigments of the granular osmiophilic deposits, including the classic infantile type Santavuori-Haltia, apparently do not, the latter type exhibiting sphingolipid activator proteins. The nosologic significance of both the subunit C of the adenosine triphos-phate synthase and the sphingolipid activator proteins, although they make up a considerable amount of the crude auto-fluorescent lipopigments in neuronal ceroid-lipofuscinosis, is still unclear. In spite of numerous pathogenetic principles invoked, such as a defect in lipid peroxidation, abnormalities of dolichols and dolichol phosphates, and defects in pro-tease inhibitors, precise pathogenesis and etiology of the neuronal ceroid-lipofuscinoses remain elusive. Recent promis