Abnormalities of glycosphingolipids in mucopolysaccharidosis type III B.

Glycosphingolipids from brain, liver, and spleen of a patient with mucopolysaccharidosis type III B were quantitatively analyzed. Neutral glycosphingolipids containing glucosylceramide, lactosylceramide, globotriaosylceramide, globotetraosylceramide, and gangliotriaosylceramide were increased in the brain, while the contents of galactosylceramide and galactosylceramide I3-sulfate were decreased. The total ganglioside levels were low in the grey matter (522 micrograms N-acetylneuraminic acid/g) and high in the white matter (342 micrograms N-acetylneuraminic acid/g), when compared with the normal values (744-918 micrograms/g in grey matter and 80-180 micrograms/g in white matter). The ganglioside compositions were characterized by a high proportion of II3-N-acetylneuraminosylgangliotriaosylceramide (GM2), II3-N-acetylneuraminosyllactosylceramide (GM3), and II3-(N-acetylneuraminosyl)2lactosylceramide (GD3). An unusual band of protein in place of an ordinary band of Wolfgram protein was detected as a major band by sodium dodecylsulfate-polyacrylamide gel electrophoresis. The low levels of 4-eicosasphingenine in the brain gangliosides indicated that the disturbance of the sphingolipid metabolism already began at age 3 at the latest and that the brain remained immature. These abnormal glycosphingolipids and protein as well as the accumulation of heparan sulfate explain in part the severe progressive mental retardation which is most characteristic of the mucopolysaccharidosis III B. Abnormalities of glycosphingolipids in the liver and spleen are also found.