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

Turnaround Time

2 weeks

CPT Code(s)

81479

Cost

$500

Genes

• Pompe disease Glycogen Storage Disease Type II

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.

Molecular testing is useful to confirm the diagnosis and to identify the disease causing mutations within a family to allow for carrier testing and prenatal diagnosis.

multiplex ligation-dependent probe amplification (MLPA)

According to GeneReviews, 83-93% of patients with Pompe disease have sequence variants, and 5-13% have copy number variants.

The preferred sample type is 3-5 ml of peripheral blood collected in an EDTA (purple top) tube. Extracted DNA and saliva are also accepted for this test. Saliva samples must be submitted in an approved saliva kit. Contact the lab to receive a saliva kit or to have one sent to your patient.

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.

Prenatal diagnosis is available if the familial mutations are known. Additional fees for cell culture and maternal cell contamination may apply. Maternal cell contamination studies are required for all prenatal molecular tests. Contact the laboratory prior to sending a prenatal specimen.