Aspartylglucosaminuria: A recessively inherited, progressive lysosomal storage disease caused by a deficiency of GLYCOSYLASPARAGINASE activity. The lack of this enzyme activity results in the accumulation of N-acetylglucosaminylasparagine (the linkage unit of asparagine-linked glycoproteins) in LYSOSOMES.Aspartylglucosylaminase: An enzyme that catalyzes the conversion of N(4)-(beta-N-acetyl-D-glucosaminyl)-L-asparagine and water to N-acetyl-beta-D-glucosaminylamine and L-aspartate. It acts only on asparagine-oligosaccharides containing one amino acid, i.e. the ASPARAGINE has free alpha-amino and alpha-carboxyl groups. (From Enzyme Nomenclature, 1992)Lysosomal Storage Diseases: Inborn errors of metabolism characterized by defects in specific lysosomal hydrolases and resulting in intracellular accumulation of unmetabolized substrates.Acetylglucosamine: The N-acetyl derivative of glucosamine.