Hunter Syndrome (MPS II): Iduronate-2-Sulfatase Enzyme Analysis

Clinical Information

Hunter syndrome is an X-linked lysosomal storage disorder caused by a deficiency of iduronate-2-sulfatase. Features include coarse facial appearance, short stature, hepatosplenomegaly, intellectual disability and joint stiffness.

Technical Information

Iduronate-2-sulfatase enzyme activity is measured using a 4-methylumbelliferyl (4-MU) substrate (leukocytes, plasma, fibroblasts) or liquid chromatography-tandem mass spectrometry (LC-MS/MS) (DBS).

Specimen Requirements

• Accepted sample types for this test include dried blood spots (DBS), fibroblasts, leukocytes, and plasma.
• DBS: Approximately 75 uL of blood should be applied to each of the five circles on filter paper dried blood spot card. Allow blood to dry for at least 4 hours before shipping.
• Fibroblasts: Tissue sample should be stored in sterile culture media; cultured fibroblasts should be sent in two T25 flasks. Do NOT place tissue in formalin or formaldehyde. Do not freeze tissue.
• Leukocytes: A minimum of 5 mL whole blood (7-10 mL preferred) collected in a sodium heparin tube
• Plasma: A minimum of 3 mL whole blood collected in a sodium heparin tube; or blood can be centrifuged and a minimum of 1 mL plasma removed and sent for analysis.

Transport Instructions

• DBS: Ship DBS card at ambient temperature.
• Fibroblasts: Ship tissue sample or cultured fibroblasts at ambient temperature
• Leukocytes: Whole blood should be shipped at ambient temperature. If leukocytes are being isolated at another laboratory, the pellet should be frozen after specimen processing and shipped frozen on dry ice.
• Plasma: Plasma should be frozen after collection and shipped frozen, preferably on dry ice. Whole blood should be shipped at ambient temperature.