Contributor: Gordon K. Klintworth
N-acetylgalactosamine-4-sulfatase deficiency (Maroteaux-Lamy syndrome, mucopolysaccharidososis type VI, arylsulfatase B deficiency, OMIM # 253200) is one of the mucopolysaccharidoses. This lysosomal storage disease resembles mucopolysaccharidosis type II clinically, but marked corneal clouding is present. Mild, intermediate, and severe phenotypes occur. Unlike mucopolysaccharidosisis type I-H, affected individuals survive longer and have a normal intelligence. There is an excessive urinary excretion and tissue storage of dermatan sulfate due a deficiency of N-acetylgalactosamine-4-sulfatase caused by a mutation in the ARSB gene. Ocular manifestations are prominent features of mucopolysaccharidosis type VI. Marked corneal clouding is present. Cells in numerous sites [corneal stroma (keratocytes as well as between the collagen lamellae), Bowman layer, trabecular meshwork, sclera, corneal epithelium, corneal endothelium, non-pigmented epithelium of ciliary body) contained granular fibrillary material within membrane bound vacuoles. Glycosaminoglycans are stored within affected cells. In both the mild and severe phenotypes of mucopolysaccharidosis type VI the basal epithelial cells and fibroblasts of the cornea contain numerous single-limited vacuoles with finely granular and membranous lamellar material as in several other mucopolysaccharidoses. The corneal fibroblasts are less involved in the mild cases than in the severe ones. In autopsy studies of individuals, who have died from the disorder the parafoveal retina contained fewer ganglion cells than normal, but unlike several other mucopolysaccharidoses, a pigmentary retinopathy has not been reported. The posterior sclera is marked thickened (2.5 x normal). Optic atrophy is common and may be secondary to papilledema which follows a communicating hydrocephalus. In patients with mucopolysaccharidosis type VI significant corneal clearing has not followed bone marrow transplantation, but clearing of the recipient cornea adjacent to the graft has been described in two patients.