Recent findings on some "new" neurometabolic diseases.

The most common inborn error of glycoprotein catabolism appears to be aspartylglycosaminuria (AGU). It is characterized by deepening mental retardation, progressive lesions of connective tissue, and increased urinary excretion of aspartyglycosylamine. The first symptoms usually appear after 3 years of age and closely resemble those of Hurler's disease. The condition is a hereditary lysosomal storage disease due to a defective enzyme. The main clinical findings in a infantile type of neuronal ceroid-lipofuscinosis (INCL) are psychomotor retardation, visual failure, and a virtually isoelectric E.E.G. at the final stage of the disease. The symptoms of this hereditary disorder first appear between 8 and 18 months of age and the mean age at death is 6.5 years. Striking cerebral and cerebellar atrophy, together with neuronal loss and accumulation of lipofuscin-like material, can be observed at neuropathological examination.