[Late diagnosis of Morquio syndrome. Clinical histopathological findings in a rare mucopolysaccharidosis]

Abstract

Background: The Morquio syndrome is a rare autosomal-recessive mucopolysaccharidosis. The Morquio syndrome is characterized by a reduced activity of N-acetylgalactosamine-6-sulfate-sulfatase (type A), or beta-galactosidase (type B). This deficiency leads to a lysosomal storage disease with accumulation of keratan sulfate und chondroitin-6-sulfate in connective tissue, skeletal system und teeth. Consequently, abnormalities of the skeletal system, aortic valvular disease and dental abnormalities occur. Ophthalmologically, diffuse corneal opacification and alterations of the trabecular meshwork--occasionally leading to glaucoma--can be found.

Case report: A 44-year-old woman asked for perforating corneal transplantation because of corneal clouding on both eyes. Besides, she suffered from dwarfism of unclear reason. The diffuse corneal clouding and the dwarfism suggested a systemic-metabolic disease. Thus, further radiologic and medical investigation was started.

Results: Radiologically, a kyphoscoliosis, a pectus carinatum, a luxation of both hips, and a gonarthrosis were recognized. Fibroblast culture of a skin biopsy showed reduced activity of N-acetyl-galactosamine-6-sulfate-sulfatase. This was the proof of Morquio syndrome type A. The explanted corneal button showed granules of acid mucopolysaccharides. Those were in the epithelial and endothelial cells and in the corneal stroma.

Conclusions: To our knowledge, a Morquio syndrome has never been diagnosed with an adult and only after the ophthalmologist gave a hint. This can only be explained by the comparative mild expression of the disease in this patient. Diagnosis of Morquio syndrome is important because the frequent odontoid hypoplasia can lead to a deadly atlanto-axial instability, if not treated.