Neurological manifestations of mucopolysaccharidoses

Mucopolysaccharidoses (MPS) are a group of rare progressive storage diseases that occur in about 1:25,000 individuals. They are caused by inherited partial or complete defi ciency of lysosomal enzymes involved in the breakdown of glycosaminoglycans. Partially degraded glycosaminoglycans accumulate in most cells and extracellular tissue and are excreted in urine. Clinical presentation is complex and can vary from severe disorders, which end in death in the fi rst months or years of life, to those that manifest with mild symptoms and have normal lifespan. Common symptoms include dysostosis multiplex, craniofacial dysmorphism, hepatosplenomegaly, joint stiff ness and contractures, cardiomyopathy, valve disease, frequent respiratory infections, and in some forms the central nervous system involvement. Enzyme replacement therapy for MPS type I, II, IVA, VI and VII with bone marrow transplantation in MPS I have improved the prognosis in many patients. However, enzyme replacement therapy does not prevent development of neurological manifestations. The severe and life-limiting nature of neurocognitive problems in patients with MPS requires early diagnosis and treatment to limit irreversible tissue damage. Eff ective treatments for MPS disorders must aim to prevent or stop development of both somatic and neurological manifestations. An accurate clinical description of neurological manifestations in patients, as well as proper understanding of the underlying pathological basis can help in early identifi cation of patients, design of clinical studies and development of eff ective therapies.

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