Genetic mucopolysaccharidoses, mannosidosis, sialidosis, galactosialidosis, and I-cell disease. Ultrastructural analysis of cultured fibroblasts.

The cultured skin fibroblasts biopsied from 6 cases of galactosialidosis, 4 of I-cell disease, 3 of Scheie syndrome and one of Sanfilippo B syndrome, Morquio A syndrome, sialidosis, and mannosidosis, respectively, were investigated electron microscopically to detect any cytoplasmic storage inclusions. In the cases of genetic mucopolysaccharidosis, vacuolar inclusions containing fine reticulogranular materials of low electron density predominated, showing no significant difference in fine structure among the Sanfilippo B syndrome, Scheie syndrome, and Morquio A syndrome. Similar storage inclusions were observed in sialidosis and mannosidosis and also revealed no obvious difference among the diseases and the above-mentioned syndromes of genetic mucopolysaccharidosis. In galactosialidosis, two types of inclusions, vacuolar and lamellar, were distinguished, resembling those usually seen in generalized gangliosidosis. In I-cell disease, the cytoplasmic storage inclusions were variegated; vacuolar, concentric lamellar or osmiophilic amorphous. The availability of electron microscopy in tissue culture is discussed for making the diagnosis of these diseases, and the pathogenesis of lysosomal storage inclusions in the cultured cells of the diseases is briefly viewed.