This suggestion is strengthened by whole body MRI imaging data showing apparent pathology in lumbar extensor and abdominal muscles of Pompe patients (Carlieret al., 2011). That study also revealed that patients with the mostimpaired respiratory function had the most substantial alterationsin the intercostal muscles. Respiratory muscle dysfunction andhistopathology is also prominent in Pompe animal models (Mahet al., 2007, 2010). For example, the in vitro contractile force gen-erated by the Gaa−/−mouse diaphragm is substantially bluntedcompared to wild-type control mice, and histological and biochem-ical evaluation shows profound glycogen accumulation. Thus, theliterature has unequivocally established that diaphragm weaknessis a hallmark feature of Pompe disease, and it is likely that the accessory respiratory muscles are also impaired. In this review, however,we emphasize that ventilatory failure in Pompe disease reflectsa complex interplay between neural and muscular function (seeSection 8).