Pompe Disease Second-Tier Newborn Screening, Blood Spot
Use
Pompe disease, also known as glycogen storage disease type II, is an autosomal recessive disorder caused by a deficiency of the lysosomal enzyme acid alpha-glucosidase (GAA). This second-tier test is crucial for newborns with an abnormal primary screening result for Pompe disease, characterized by decreased acid alpha-glucosidase enzyme activity. It helps differentiate true cases of infantile and late-onset Pompe disease from false positives, including carriers and pseudodeficiency cases. A positive test result supports further molecular genetic analysis of the GAA gene, aiding in early diagnosis and treatment with enzyme replacement therapy.
Special Instructions
For collection instructions, refer to the Blood Spot Collection Instructions available in multiple languages. This test is specifically designed for newborns up to 6 weeks of age, owing to different reference ranges. Ordering physicians must note birth weight, time of birth, and gestational age on the test request form.
Limitations
This test may not detect some milder or later onset forms of Pompe disease. Carrier status for Pompe disease cannot be reliably detected using this assay alone. An abnormal result is indicative but not definitive for a diagnosis, necessitating follow-up confirmatory biochemical or molecular assays coordinated by local genetic experts.
New York Approved
Methodology
Mass Spectrometry (Flow Injection Analysis Tandem Mass Spectrometry (FIA-MS/MS))
Biomarkers
LOINC Codes
- 63416-2
- 8339-4
- 57715-5
- 76516-4
- 63416-2
- 18771-6
Result Turnaround Time
2-3 days
Related Documents
For more information, please review the documents below
Specimen
Whole Blood
Volume
3 Blood spots
Minimum Volume
1 Blood spot
Container
Blood Spot Collection Card
Collection Instructions
Completely fill at least 3 circles on the filter paper card, let blood dry at ambient temperature for a minimum of 3 hours. Do not expose to heat or direct sunlight. Keep dry.
Causes for Rejection
Blood spot specimen that shows serum rings, has multiple layers, or insufficient specimen.
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | 28 days |
| Refrigerated | 90 days |
| Frozen | 90 days |