Definition:

Glycoproteinoses are a group of autosomal recessive lysosomal storage diseases caused by deficient activities of enzymes that play important roles in the degradation of glycoproteins such as N-linked or O-linked oligosaccharides. The lack of a single enzyme leads to the complete blockage of the catabolic chain and results in the accumulation of undegraded oligosaccharides in lysosomes. Glycoproteinoses share many clinical features such as mental retardation, coarse facies, and dysostosis multiplex. Cathepsin A-deficiency causes combined sialidase and beta-galactosidase deficiency (Sialidosis and Galactosialidosis) due to its function in stabilising these two hydrolases.