About Pompe Disease
Pompe Disease, also known as glycogen storage disease type 2, is an autosomal recessive genetic disease. This means that both parents are carriers of a mutated gene that they pass to the baby, causing the disease. Pompe Disease is caused by a lack of, or deficiency of an enzyme called GAA. The enzyme GAA is needed to break down the sugar molecule glycogen. Without GAA, glycogen molecules start to build up in the smooth, skeletal, and cardiac muscle cells. This causes a variety of symptoms that include muscle weakness, cardiomyopathy, liver enlargement and respiratory failure. Progression of the disease can lead to dependency on a ventilator to breathe, a feeding tube, becoming wheelchair bound, and sometimes death.
Infantile Pompe Disease
Infantile Pompe Disease is the most severe form. Pompe afflicted babies make very little GAA or none at all. This causes a rapid buildup of glycogen in the heart, skeletal muscles, and liver. Signs and symptoms of the infantile form of Pompe Disease usually develops in the first few months of life, and include an enlarged heart and liver, as well as muscle weakness. Babies are “floppy” in appearance; don’t meet their milestones, and may struggle with feeding and growth. They may exhibit heart failure symptoms including, chest pain, fatigue, shortness of breath, excessive sweating, and poor appetite. They can also have irregular heartbeats and arrhythmias, causing the potential for sudden death. If the infant with Pompe Disease is not treated, death will occur from heart or respiratory failure within the first year or two of life. Some states have started newborn screening for Pompe Disease to get infants on treatment as soon as possible, giving them a better outcome and increased chance of survival. However, many states, including Oregon have not added Pompe Disease to their newborn screening resulting in delayed diagnosis.
Late-onset Pompe Disease
Late-onset Pompe Disease, can manifest at any age, including babies. People with late-onset can have varying degrees of muscle weakness, including weakness of the respiratory muscles. Cardiac involvement does not usually occur in people with late-onset Pompe Disease. The disease typically progresses more slowly in individuals with late-onset, because they have varying amounts of the enzyme GAA. Glycogen buildup develops at a slower rate, but can still lead to severe complications including, swallowing difficulties and respiratory failure. It can take years for a correct diagnosis due to the symptoms resembling other neuromuscular disorders.
Enzyme Replacement Therapy
Enzyme replacement therapy (ERT), is the only treatment for Pompe Disease at this time. It works to replace the deficient enzyme with weekly, or bi-weekly infusions of a genetically engineered form of GAA. The effects of ERT have saved countless lives. With ERT, the heart will shrink back to normal, or near normal size in infants. It can help to stop the progression and even improve some of the muscle weakness associated with Pompe Disease. However, ERT is a treatment, not a cure. It cannot reach all the cells in the body, thus symptoms can, and usually do progress, even with enzyme replacement therapy. Pompe Disease is a progressive, which is why it is so important to raise awareness and funds for research and advancement of new treatments, therapies, and one day a cure.