Mucopolysaccharidosis type IV (MPS4) is an autosomal recessive lysosomal storage disorder caused by a defect in one of the enzyme genes involved in glycosaminoglycan degradation. The defect results in the accumulation of keratan sulfate and chondroitin sulfate in many organs, as well as elevated metabolite levels in urine. Common signs and symptoms include normal cognition, coarse faces, and dysostosis multiplex.
