Cognitive decline in classic infantile Pompe disease: An underacknowledged challenge

Classic infantile Pompe disease is a progressive lysosomal glycogen storage disorder, which, if untreated, leads to severe skeletal muscle weakness, inability to achieve any motor milestones, and death in the first year. In 1999, we reported the first successful use of enzyme replacement therapy (ERT).1Since then, patients' outcome with respect to survival, cardiac function, and motor performance has improved significantly. The oldest patient is currently 16 years old. Although glycogen storage occurs in the brain as well, and ERT cannot pass the blood–brain barrier, so far clinical studies show normal to mildly delayed cognitive development.2,3