Electron Microscopy of Storage Cytosomes in Kufs' Disease

THE FINDINGS of a deficiency of β-D-N-acetylhexosaminidase component A in Tay-Sachs disease 1 and β-galactosidase in generalized gangliosidosis 2 provide us a plausible explanation for different, GM 1 and GM 2 , ganglioside accumulation in these diseases. Furthermore, the fact that these enzymes are localized in lysosomes sheds light as to why the stored lipoid materials are constantly associated with lysosomal or lipofuscin components of neurons on electron microscopy. 3-10 It is conceivable that a deficiency of different enzymes involved in the catabolism of gangliosides may be involved in various clinical subtypes of amaurotic idiocy. As of this date, six clinical subtypes of amaurotic idiocy have been recognized: (1) congenital, 11,12 (2) infantile, 13,14 (3) late infantile, 15,16 (4) systemic late infantile, 17,18 (5) juvenile, 19-21 and (6) adult. 22 In 1925, Kufs 22 described the first patient with the adult variety of Tay-Sachs disease whose neurologic symptoms started at