Urinary GAG testing
The level of urinary glycosaminoglycans (GAGs) is increased in patients with any MPS syndrome, so detection of excessive urinary GAGs is usually the first diagnostic indicator (unless a strong family history allows this stage to be bypassed).1,2
Urine samples should be analyzed via chromatography or electrophoresis to identify abnormal GAG patterns even if their levels are not elevated.1 A negative GAG test does not necessarily rule out Hunter syndrome (MPS II) as a diagnosis.1,2
Detection & diagnosis of MPS II Dr. David Whiteman
Part 3 of the MPS II Global Webinar
Review how Hunter syndrome (MPS II) is detected and diagnosed.
Testing for absent or very low iduronate-2-sulfatase (I2S) activity is diagnostic for Hunter syndrome. Enzyme activity can be measured in cultured fibroblasts, leukocytes, plasma or serum, or dried blood spots.1,2
Second sulfatase testing
A second sulfatase should be measured to rule out multiple sulfatase deficiency, and confirm the diagnosis of Hunter syndrome.1,2
Over 330 alterations in the I2S gene have been reported in Hunter syndrome patients. Once a likely disease-causing mutation has been identified, all family members may be tested to identify carriers or those at risk, and counseling should be provided.1,2
If you suspect Hunter syndrome, refer your patient to a medical geneticist for an accurate diagnosis.