The Morquio syndrome (mucopolysaccharidosis IV): Morphologic and biochemical studies

The Morquio syndrome (mucopolysaccharidosis IV) is a lysosomal storage disease characterized clinically by dwarfism, corneal opacities, dental abnormalities, cardiopulmonary complications, normal intelligence, dysostosis multiplex with universal platyspondyly, and excessive urinary excretion of keratosulfate. The purpose of this communication is to report morphologic observations of Morquio skin and cartilage, and biochemical studies of cultured fibroblasts and cartilage-derived cells. Cells of the basal and Malpighian layers of the epidermis contain large single-membrane-bound vacuoles whereas other dermal cells types are normal. Chondrocytes are packed with similar vacuoles. Preliminary studies of mucopolysaccharide (MPS) metabolism of cultured Morquio cartilage-derived cells and fibroblasts reveals excessive intracellular MPS accumulation in cartilage-derived cells but only modest accumulations in fibroblasts. The Morquio syndrome appears to be a cell-type specific MPS storage disorder, and further studies to elucidate the presumed deficiency of lysosomal hydrolase(s) should be directed at tissues displaying both morphologic and metabolic abnormalities.