Iduronate-2-Sulfatase, Blood Spot
Use
This test supports the biochemical diagnosis of mucopolysaccharidosis II (MPS II; Hunter syndrome), an X-linked lysosomal disorder caused by the deficiency of the iduronate sulfatase enzyme. It is useful for individuals with positive newborn screen results or clinical signs and symptoms suspicious for MPS II. While this test can detect enzyme deficiency, additional biochemical or molecular genetic analyses are required for confirmation. Early diagnosis and treatment are crucial, as therapies such as hematopoietic stem cell transplantation and enzyme replacement have been shown to improve clinical outcomes.
Special Instructions
Patient's age and reason for testing are required to be documented. Ensure that informed consent for genetic testing is recorded for New York clients. Proper submission of the test request is crucial. It is important to follow the specific collection instructions for blood spots and maintain the specimen dry to avoid contamination with serum rings or layers.
Limitations
This test is not useful for determining carrier status for MPS II. Individuals with pseudodeficiency alleles might show reduced enzyme activity. Carrier status (heterozygosity) and enzyme levels in treated individuals may not be reliably detected. Additionally, enzyme activity for iduronate-2-sulfatase may be deficient in individuals with multiple sulfatase deficiency.
New York Approved
Methodology
Mass Spectrometry (LC-MS/MS)
Biomarkers
LOINC Codes
- 79462-8
- 42349-1
- 79462-8
- 59462-2
- 18771-6
Result Turnaround Time
8-15 days
Related Documents
For more information, please review the documents below
Specimen
Dried Blood Spot
Volume
2 Blood spots
Minimum Volume
1 Blood spot
Container
Blood spot collection card
Collection Instructions
Alternative collection for patients older than 1 year is a fingerstick. Let blood dry on the filter paper at room temperature in a horizontal position for 3 hours. Avoid heat, direct sunlight, and stacking wet specimens. Keep dry.
Causes for Rejection
Blood spot specimen that shows serum rings or has multiple layers. Insufficient specimen. Unapproved filter papers.
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | 7 days |
| Refrigerated | 60 days |
| Frozen | 60 days |