Investigating Pompe Prevalence in Neuromuscular Medicine Academic Practices

The incidence of type II glycogen-storage disease (Pompe disease) varies depending on
ethnicity and geographic region. As of 2010, nine studies have been published documenting the
incidence of Pompe disease. It is most common within the African American population, with an
incidence of 1 in 14,000. In the U.S. more broadly speaking, the combined incidence of all
three variants of the disease is 1 in 40,000. These estimates relied on the frequencies of
three mutations in the gene acid alpha-glucosidase (GAA), leading to variants of the disease.
Criteria for inclusion in the studies were often non-selective; in many cases, molecular
genetic screening was done at birth. With such a high prevalence of Pompe disease reported,
it is expected that large university medical centers specializing in neuromuscular diseases
would see a higher incidence of Pompe disease among their patients. From a comparable Italian
multicenter study, it appears that Pompe disease accounts for 3% of all patients presenting
with proximal weakness with or without CK elevation.

This study will measure the incidence of Pompe disease based on manifest laboratory
abnormality, namely low GAA enzyme activity. Analysis of GAA enzyme activity will be
determined through a blood sample of 4 mL. The study seeks to measure the epidemiology of
Pompe disease by symptomatically screening all patients who present with symptoms of hitherto
undiagnosed proximal weakness with or without elevation of the muscle enzyme, creatinine
kinase (CK), or elevation of CK alone, at thirteen academic tertiary neuromuscular practices
throughout the United States and Canada. Total recruitment is expected to be ~1,500
participants. It is anticipated that the number of incident Pompe cases in this cohort would
be between 3-5%, i.e. 45-75 newly diagnosed cases of Pompe disease.