Definition:

GM1-gangliosidosis is an autosomal recessive lysosomal storage disorder caused by deficient beta-galactosidase activity. The enzymatic defect results in the accumulation of GM1 ganglioside in nervous tissues and a highly variable storage of keratan sulfate and glycopeptides in visceral and skeletal tissues. There are three main clinical variants, infantile (type I), juvenile (type II), and adult (type III), categorized by severity of symptoms and variable residual enzymatic activity of beta-galactosidase.