ABSTRACT
Features of GM1 gangliosidosis and sialidosis result from defective activity of both -galactosidase and neuraminidase as a result of fundamental deficiency in the lysosomal PPCA.
Following the discovery in 1968 of -galactosidase deficiency in generalized GM1 gangliosidosis [1], a number of patients were reported with atypical features such as cherry red macular spots and an absence of hepatosplenomegaly [2-5]. The combination of features of cerebral lipidosis and mucopolysaccharidosis without mucopolysacchariduria suggested a mucolipidosis. Complementation studies in somatic cell hybrids indicated that two of these patients [4,5] had mutations distinct from or non-allelic with GM1 gangliosidosis, though
they were clearly deficient in -galactosidase [6]. Wenger et al. [7] in 1978 reported the coexisting deficiency of neuraminidase and -galactosidase in leukocytes and fibroblasts of a patient with what had been thought [8] to be a variant form of GM1 gangliosidosis. Then other patients were reported in whom sialidase deficiency was present [9-12] along with that of -galactosidase.
