Pompe disease (PD) is an autosomal recessive lysosomal storage disease caused by deficient acid α-glucosidase (GAA) activity, which results in progressive, debilitating, and often lifethreatening symptoms, involving musculoskeletal, respiratory, and cardiac systems.In classical infant-onset Pompe disease (IOPD), symptoms start very early in life, and death occurs soon afterward if the disease remains untreated.Recently, enzyme replacement therapy (ERT) with recombinant human GAA (rhGAA) has become a possible treatment regimen, but the best outcomes in motor function can only be achieved when treatment was initially early and in patients without neutralizing a nti-rhGAAantibodies in the blood.