Mucopolysaccharidosis type II and type VI: Hunter syndrome and Maroteaux-Lamy disease

Mucopolysaccharidosis type II and VI are rare lysosomal storage disorders, caused by a deficiency of specific enzymes involved in the breakdown of glycosaminoglycans. Characteristic features include hepatosplenomegaly, hernia inguinalis and umbilicalis, coarse facial features, skeletal abnormalities, joint stiffness, limited growth and cardiorespiratory problems. Severe mental retardation may also be present in patients with MPS II. Both diseases present as a spectrum with large differences in severity and progression between patients. Symptoms may also be relatively mild; in those cases the diagnosis can easily be missed. Recently enzyme replacement therapy with idursulfase (MPS II) and galsulfase (MPS VI) became available, but experience with the treatment is still limited. Continued and structured follow-up of both treated and untreated patients is necessary to fully evaluate the long-term effects. An early diagnosis for these disorders is important given the new therapeutic possibilities and to timely initiate supportive treatment.