Mucopolysaccharidosis

Mucopolysaccharidoses (MPS ) are reckoned to the group of lysosomal storage diseases. They are based on heritable disorders of enzymatic degradation of acid mucopolysaccharides ( glycosaminoglycans ) by lysosomal hydrolases. The non-degraded glycosaminoglycans are stored in the lysosomes. This eventually leads to disturbances of cellular metabolism and in severe cases, death. This mainly affects tissue of the skeletal system, the central nervous system, visceral organs, skin, and the endocardium.

There are four types of glycosaminoglycans stored. Depending on the different distribution pattern, and according to clinical criteria can be doing various major forms of mucopolysaccharidosis differ, which in turn are divided into different subtypes.

These subtypes indicate either different clinical manifestations of the same enzyme defect (eg, mild and severe form of Hunter syndrome ) or different biochemical defects of the clinical features ( eg Morquio A and B).

In almost all types, there are severe and mild remitting forms. An assignment is limited only by the clinical course and the speed with which the disease progresses, are possible.

Classification

Symptoms

Symptoms vary depending on the type of mucopolysaccharidosis. At birth, children are initially unremarkable. Almost all types are associated with involvement of the skeleton and the corresponding deformation of the bones, shortening of tendons and ligaments at the joints ( contractures ), short stature and coarsened facial features. The store also usually leads to a marked enlargement of the liver ( hepatomegaly ). Depending on the type enters a progressive loss of mental abilities. There may be clouding of the cornea and deafness. Many children with mucopolysaccharidosis have abdominal hernias and frequently recurring respiratory infections.

Diagnosis

The diagnosis is first made ​​by the detection of an increased excretion of glycosaminoglycans in the urine. The increase falls in types III and IV of sometimes so low that coarse screening tests can be normal here. With appropriate excretion pattern can then confirm the suspicion determination of the activity of the corresponding enzyme in white blood cells (leukocytes) or in fibroblasts.

Therapy

Since it is congenital hereditary disease, a causal therapy is not yet possible, although there are research approaches for gene therapy for the mucopolysaccharidoses. For individual types exists enzyme replacement therapy with iduronidase, which can be used with secure benefits when it begins before the onset of symptoms. Also a timely bone marrow transfer, the patient may benefit certain types because the transferred blood cells do not carry the enzyme defect and can accept the degradation of glycosaminoglycans.