Chapter 31 – The Mucopolysaccharidoses

The mucopolysaccharidoses are a group of inherited disorders caused by specific enzyme deficiencies in the degradation of the glycosaminoglycans (mucopolysaccharides). Enzyme deficiencies result in the accumulation of glycosaminoglycans in lysosomes of various tissues and in the excessive excretion of partially degraded glycosaminoglycans in urine. Clinical manifestations of the mucopolysaccharidoses depend on the specific enzyme deficiency, the end organ affected, and the accumulation of glycosaminoglycans in the affected organs. In diseases in which the brain is not involved, there is no mental retardation. On the other hand, if the brain is affected and other somatic manifestations are minimal, the coarse features that are characteristic of the mucopolysaccharidoses are not as prominent. Specific degradative lysosomal enzyme deficiencies have been identified for all the mucopolysaccharidoses. The glycosaminoglycans that are stored and excreted in the urine of the various mucopolysaccharidoses are dermatan sulfate, heparan sulfate, keratan sulfate, and chondroitin 4/6 sulfates.