Pompe Disease, Glycogen Storage Disease Type II: GAA Deletion/Duplication MLPA

Clinical Information

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.

Technical Information

• This test is performed using Multiplex Ligation-dependent Probe Amplification (MLPA).
• MLPA is a molecular technique that allows the determination of dosage for specific sequences of interest that can be missed by routine DNA sequencing or other standard PCR-based methodologies (Schouten et al. 2012 Nucleic Acids Research 30, e57).
• Probes for 17 of 19 GAA coding exons (excluding exons 2 and 11), in combination with a variety of control probes, are analyzed and quantified.

Specimen Requirements

• The preferred sample type is 3-4 ml of peripheral blood collected in an EDTA (purple top) tube. Extracted DNA and saliva are also accepted for this test. Blood and saliva kits are available by request.
• Send approximately 5 µg of extracted DNA at a requested concentration of 90-130 ng/µl.
• Saliva samples must be submitted in an approved saliva kit.

Transport Instructions

• The specimen should be kept at room temperature and delivered via overnight shipping. If shipment is delayed by one or two days, the specimen should be refrigerated and shipped at room temperature. Do not freeze the specimen. Samples collected on Friday can be safely designated for Monday delivery
• Extracted DNA should be sent at room temperature via overnight delivery.
• Saliva is stable at room temperature and can be delivered via overnight or ground shipping