The Pompe Registry is a global, multicenter, international, longitudinal, observational, and voluntary program for patients with Pompe disease, designed to track the disease's natural history and outcomes in patients, both treated and not. Data from the Registry are also used to fulfill various global regulatory commitments, to support product development/reimbursement, and for other research and non-research related purposes. The objectives of the Registry are: * To enhance understanding of the variability, progression, identification, and natural history of Pompe disease, with the ultimate goal of better guiding and assessing therapeutic intervention. * To assist the Pompe medical community with the development of recommendations for monitoring patients, and to provide reports on patient outcomes, to optimize patient care. * To characterize the Pompe disease population. * To evaluate the long-term effectiveness of alglucosidase alfa.