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Pompe Disease

About Pompe disease

Pompe disease, also known as acid maltase deficiency, is a rare and progressive autosomal recessive lysosomal storage disease with a wide range of clinical phenotypes, presenting in infancy, childhood, or adulthood. Pompe disease is caused by mutations in the GAA gene leading to an absence or deficiency of the lysosomal enzyme acid α-glucosidase, essential for the degradation of glycogen. Progressive accumulation of lysosomal glycogen can affect all muscle types.

Pompe disease (PD) is classified into Infantile-onset (IOPD) or Late-onset (LOPD)

  • Infantile-onset Pompe disease presents prior to 1 year of age and is characterized by elevated CK, profound muscle weakness, cardiomegaly, and cardiomyopathy. IOPD is rapidly progressive, typically leading to death by cardiorespiratory failure by 1 year of age if left unmanaged. IOPD may be suspected in infants with muscle weakness, hypotonia (“floppiness”), delayed motor milestones, a weak suck, feeding and swallowing defects, and failure to thrive.
  • Late-onset Pompe disease can present in childhood or adulthood with progressive proximal muscle weakness and respiratory insufficiency. CK may or may not be elevated. When abnormal, muscle biopsy typical findings include vacuolated muscle fibers, PAS-positive vacuoles (glycogen storage) and increased acid phosphatase activity in muscle fibers. Normal biopsy does not rule out Pompe. Significant morbidity is associated with LOPD, and there is a wide phenotypic range. LOPD may be suspected in children or adults with progressive proximal weakness, respiratory insufficiency, and feeding/swallowing difficulties.
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Pompe Disease

Incidence

Overall incidence estimates for the United States for all forms: 1 in 40,000* (based off ethnically diverse New York population).

*Incidence varies depending on geography and ethnic background.

Program eligibility

The Roadmap2Rare Diagnostic Program* consists of an acid α-glucosidase enzyme assay with reflex to GAA sequencing if deficient, and is for individual patients suspected of having Pompe disease via:

  • Symptoms consistent with Pompe disease
  • Presumptive positive newborn screen for Pompe disease (expedited testing available)

*This testing program is not appropriate for carrier testing.

About the test

Testing algorithm:

  • Acid α-glucosidase will be assayed and if deficient will reflex to,
  • GAA sequencing analysis (with copy number variant analysis if needed)*
  • If either enzyme assay or GAA sequencing has already been performed, these tests can be ordered individually, if needed.

*Expedited GAA sequencing with turnaround time of 7 days is available for infants with symptoms of infantile-onset Pompe disease, or those with presumptive positive Pompe disease based on newborn screening.

References

1. Diagnostic criteria for late-onset (childhood and adult) Pompe disease. Muscle Nerve. 2009;40:149-160.

2. Martiniuk F et al. Carrier frequency for glycogen storage disease Type II in New York and Estimates of affected individuals born with the disease. Am J Med Genet. 1998;79:69-72.

3. Burton B et al. The Initial Evaluation of Patients After Positive Newborn Screening: Recommended Algorithms Leading to a Confirmed Diagnosis of Pompe Disease. Pediatrics Jul 2017, 140 (Supplement 1) S14-S23; DOI: 10.1542/peds.2016-0280D.

This testing service has not been cleared or approved by the U.S. Food and Drug Administration. Testing services may not be licensed in accordance with the laws in all countries. The availability of specific test offerings is dependent upon laboratory location. The content on this page is provided for informational purposes only, not as medical advice. It is not intended to substitute the consultation, diagnosis, and/or treatment provided by a qualified licensed physician or other medical professionals.