Overview of the Mucopolysaccharidoses

The mucopolysaccharidoses (MPSs) are a group of rare, inherited lysosomal storage disorders that are clinically characterized by abnormalities in multiple organ systems and reduced life expectancy. The MPSs are heterogeneous, progressive disorders. Patients typically appear normal at birth, but during early childhood they experience the onset of clinical disease, including skeletal, joint, airway and cardiac involvement, hearing and vision impairment, and mental retardation in the severe forms of MPS I, MPS II and MPS VII and all subtypes of MPS III. There are two treatment options for patients with MPS that are directed at the underlying pathophysiology: haematopoietic stem cell transplantation, which is useful for selected patients, and recombinant i.v. enzyme replacement therapy, which is available for MPS I, II and VI. Early diagnosis and treatment can improve patient outcomes and may reduce the disease burden on patients and caregivers. As skeletal and joint abnormalities are characteristic of many patients with MPS, rheumatologists are positioned to recognize the features of the disease and to facilitate early diagnosis and referral. In this overview, the clinical features of the MPS disorders and a brief review of treatment options will be presented in order to aid the rheumatologist in recognizing the features of these rare genetic disorders.