The mucopolysaccharidoses are a group of disorders caused by the deficiency of any of the enzymes involved in the stepwise degradation of dermatan sulphate, heparan sulphate, keratan sulphate, or chondroitin-6-sulfate, which are collectively called glycosaminoglycans (GAG). Undegraded or partially degraded GAG are stored in lysosomes and excreted in the urine. Accumulation of GAG in lysosomes interferes with normal functioning of cells, tissues, and organs resulting in the clinical features observed in mucopolysaccharidosis (MPS) disorders. There are 11 known enzyme deficiencies that result in the accumulation of GAG. In addition, abnormal GAG storage is observed in multiple sulfatase deficiency and in I-cell disease. Finally, abnormal excretion of GAG in urine is observed occasionally in other disorders including active bone diseases, connective tissue disease, hypothyroidism, urinary dysfunction, and oligosaccharidosis.
Mucopolysaccharidoses are autosomal recessive disorders except for MPS II, which follows an X-linked inheritance pattern. Affected individuals typically experience a period of normal growth and development followed by progressive disease involvement encompassing multiple systems. The severity and features vary and may include facial coarsening, organomegaly, skeletal changes, cardiac abnormalities, and developmental delays. Moreover, disease presentation varies from as early as late infancy to adulthood.
A diagnostic workup for individuals with suspected MPS should begin with this test. Interpretation is based upon pattern recognition of the specific sulphates detected. However, an abnormal mucopolysaccharide analysis is not sufficient to conclusively establish a specific diagnosis. It is strongly recommended to seek confirmation by an independent method, typically in vitro enzyme assay (available in either blood or cultured fibroblasts from a skin biopsy) or molecular analysis.
After a specific diagnosis has been established, this test can be appropriate for monitoring the effectiveness of treatment, such as a bone marrow transplant or enzyme replacement therapy (ERT). This test allows for monitoring of the excretion of specific sulphates, as these may change in patients with an MPS disorder undergoing treatment.
Specialist Biochemistry
WMUC
Send to separating if ambient on arrival. Send to specialist biochemistry if frozen on arrival.
Make aliquot for UCRN. Send primary sample to specialist biochemistry.
Total mucopolysaccharides
5 weeks
5290