Human β-Mannosidase Deficiency

LYSOSOMAL disorders in humans due to deficiencies of lysosomal enzymes or effector proteins (activator or protector proteins) have been described for most steps in the catabolism of glycoproteins, glycolipids, and glycosaminoglycans (mucopolysaccharides).1 2 3 A deficiency of one of these enzymes or proteins usually results in the accumulation of undegraded storage products (some primary and others secondary to the defect), and this leads to most of the clinical features observed in the patients. Disorders affecting the catabolism of the oligosaccharide portion of glycoproteins, such as sialidosis, GM1 gangliosidosis, α-mannosidosis, Sandhoff's disease, fucosidosis, and aspartylglycosaminuria have been described previously.1 , 2 The enzyme defects . . .