Pompe disease (Glycogen Storage Disease Type II) - Enzyme Analysis
|Disease name||Pompe disease (GSD, Type II)|
|Clinical info||Pompe disease is caused by a deficiency of the enzyme alpha-glucosidase (GAA), an enzyme that at normal levels will breakdown glycogen in the body. Infantile-onset Pompe disease is characterized by hypotonia, generalized muscle weakness and hypertrophic cardiomyopathy. Death generally occurs within the first year of life due to cardiac and respiratory failure. The later-onset form shows greater variability with a slowly progressive muscle weakness and respiratory insufficiency. The degree of enzyme deficiency is generally related to the severity and age of onset.|
|Indications||This test can be used to confirm a suspected Pompe disease diagnosis. Prenatal diagnosis and carrier testing via enzyme analysis are not available.|
|Methodology||Quantifies level of alpha-glucosidase via the 4-methylumbelliferyl substrate|
Enzyme activity can be measured in leukocytes, cultured fibroblasts, or dried blood spots. For leukocytes, please send 5-10 ml of whole blood in a green top (sodium heparin) tube. For dried blood spot collection, a minimum of three circles need to be filled in. Each circle should contain one drop of blood (about 100 microliters). See the link below for additional sample collection and handling instructions.
In addition, a dried blood spot or blood drawn in an EDTA tube can be used for Pompe disease molecular analysis and may be sent for DNA banking. Please indicate on the requisition if DNA should be banked for follow-up molecular testing.
Whole blood samples (for leukocyte analysis) should be shipped at ambient temperature and must arrive at the laboratory within 24 hours of specimen collection.
Cultured fibroblasts should be sent overnight at room temperature.
For a dried blood spot: When the sample has dried 3-4 hours, fold cover at score line, over sample, and tuck into flap. Samples should be placed in the mail within 24 hours of collection. Overnight shipping is preferred.
|Turnaround time||14 days
Cell culture can take 1-4 weeks and may lengthen turnaround time.
|Cost||Leukocytes or cultured fibroblasts: $200
Dried Blood Spot Analysis: A 50% discount will be applied for enzyme analysis from a dried blood spot reducing the price to $100.
The Biochemical Lab provides diagnostic and screening tests for a variety of inherited metabolic disorders.