People with Pompe disease struggle physically and mentally. They have trouble with activities like sports and traveling due to muscle weakness and fatigue. Symptoms range from enlarged hearts in infants to severe muscle weakness and trouble breathing in adults. The disease is caused by a deficiency in the enzyme that breaks down glycogen in muscles. It is an autosomal recessive genetic disorder, so both parents must carry the defective gene for a child to be affected. The only approved treatment is enzyme replacement therapy.