What Is Pompe Disease?
Pompe disease also called glycogen storage disease type II, is an inherited disorder where the body fails to produce enough alpha-glucosidase (also called maltase), an enzyme needed to break down a type of sugar called glycogen. Without adequate amounts of alpha-glucosidase, glycogen builds up in the body, particularly in the muscles, and damages cells. Pompe disease is caused by mutations in the GAA gene. People with Pompe disease have muscle weakness that progresses over time, mainly in the muscles used for movement and breathing. The heart may also be affected. The level of alpha-glucosidase remaining is correlated to the severity of symptoms, the age of onset, and disease progression.
Pompe disease is separated into two forms, the infantile-onset form and the late-onset form. These forms are described below.
Infantile-onset Pompe disease is the most severe form because alpha-glucosidase function is entirely absent. Muscle weakness and poor muscle tone causes infants to have trouble moving, holding up their heads, and feeding. They have trouble gaining weight and grow at a slower pace. Infants also have trouble breathing, which can worsen with lung infections. They typically have enlarged hearts, livers, and tongues. Disease progression is usually rapid, and the most common causes of death are heart or lung failure.
Late-onset Pompe disease is less severe because some alpha-glucosidase is still present. Symptoms start with muscle weakness and breathing problems. Some individuals with late-onset Pompe disease have heart problems but without an enlarged heart. They may eventually lose the ability to walk and require a wheelchair, and they may need mechanical assistance to breathe. Disease progression is more gradual, and the most common cause of death is lung failure.
How Common Is Pompe Disease?
The incidence of Pompe disease is approximately 1 in 100,000. Infantile-onset Pompe disease is the most common form.
How Is Pompe Disease Treated?
The FDA has approved enzyme replacement therapy for both infantile-onset and late-onset Pompe disease. Enzyme replacement therapy can help maintain a healthy heart size and normal heart function and may also help improve muscle tone and strength. Individuals need to follow a protein-rich diet, attend physical therapy, and monitor and treat lung infections.
What Is the Prognosis for a Person with Pompe Disease?
In infantile-onset Pompe disease, symptoms may begin at birth but more often begin in the first few months of life. Patients typically die within the first year of life, although enzyme replacement therapy can now prolong life into early childhood. In late-onset Pompe disease, symptoms can begin at any age from childhood to adulthood, and the lifespan depends on how early symptoms begin. The most common cause of death in individuals with Pompe disease is lung failure.