[Laboratory diagnosis and follow up of mucopolysaccharidoses]

Mucopolysaccharidoses (MPS) often raise diagnostic challenges, particularly in patients with progressive disease and relatively non-specific signs and symptoms. Early diagnosis improves management and enables to start specific treatment when available. Each type of MPS is associated with a deficiency of a lysosomal enzyme which catalyses the degradation of glycosaminoglycans (GAGs). The initial diagnosis Wis suggested by quantifying and identifying the accumulated metabolites. Diagnosis is then confirmed by assaying the deficient enzyme, allowing diagnosis in a large majority of cases. Indirect markers, which do not arise directly from the deficient metabolic pathway and vary in concentration depending on the degree of disease progression, are used to support a diagnosis of MPS and/or monitor the efficacy of the specific treatment. Identifying the underlying genic abnormality enables family studies to be carried out and perform prenatal diagnosis.