Testing

MPS I and MPS II share many features. It can therefore be difficult to make an accurate diagnosis based on clinical presentation alone.1 Clinical presentation in combination with the appropriate diagnostic tests ensures diagnosis of the correct MPS subtype.  

A diagnosis of MPS I or MPS II is based on quantitative testing of GAG concentration in urine and enzyme activity in tissue.1 The urinary GAG (UGAG) assay is the initial diagnostic step when an MPS disorder is suspected. A positive UGAG result is followed up by measurement of enzyme activity to confirm diagnosis.

When there is a family history of MPS I or MPS II, UGAG screening should be bypassed and an enzyme assay be performed as the first diagnostic step.2

In this section, learn more about the tests used to diagnose MPS I and MPS II.

Enzyme Assay

Enzyme Assay

Diagnosis with an MPS disorder is confirmed by demonstrating absent or deficient activity of the relevant enzyme.

What is DBS?

What is DBS?

Early recognition and management of MPS I and MPS II disease can help prevent irreversible organ damage. 

UGAG

UGAG

Individuals with MPS I/MPS II have elevated GAG levels in urine. Therefore, measurement of urinary GAG (UGAG) concentration is used as a screening test when there is clinical suspicion of MPS I/MPS II.

References

  1. 1.Lehman TJ, Miller N, Norquist B, Underhill L, Keutzer J. (2011) Diagnosis of the mucopolysaccharidoses. Rheumatology (Oxford) 50 Suppl 5: v41-48.
  1. 2.Burton BK, Giugliani R. (2012) Diagnosing Hunter syndrome in pediatric practice: practical considerations and common pitfalls. Eur J Pediatr 171(4): 631-639.