Glycolipid abnormalities in a myoclonic variant of late infantile amaurotic idiocy

Glycolipids were isolated from the brain of a patient with a myoclonic variant of late infantile amaurotic idiocy. There was an abnormal glycolipid pattern in gray and white matter. The observed high concentration of gangliosides was due to a uniform accumulation of all four major gangliosides and was not limited to one species such as ganglioside A(1), as in Tay-Sachs disease, or ganglioside A(2), as in gangliosidosis-Gm1. Two additional stored substances were identified as ceramide lactoside and ceramide tetrahexoside. Partial and total hydrolysis of these ceramide hexosides revealed that their ceramide moiety is identical with the ceramide portion of gangliosides. The sequence of hexoses in the carbohydrate chain of the ceramide dihexoside and ceramide tetrahexoside further suggests a metabolic and chemical relation to gangliosides. Some implications of these findings for the theories of the metabolic defects in gangliosidoses are discussed.