Glycogen storage disease type II, or Pompe disease, is a rare lysosomal disease. When symptoms appear and which symptoms appear vary widely among patient cases. Regardless of the time of onset, the disease is due to a deficiency in alpha-glucosidase (GAA).
The GAA deficiency typically leads to an accumulation of glycogen in the cells, which causes progressive weakness and impairs the functionality of certain tissues, organs, and muscles.
The classic form of infantile-onset Pompe disease commonly presents within a few months of birth, and if left untreated, can lead to heart failure and death before the patient’s first birthday. The nonclassic form of infantile-onset Pompe disease usually appears by age 1, and most children with only live into early childhood. Late-onset Pompe disease is usually milder than the infantile-onset forms and is less likely to involve the heart. However, as the condition evolves, breathing problems can lead to complete respiratory failure.
Signs and Symptoms
Muscle weakness (myopathy)
Poor muscle tone (hypotonia)
Enlarged liver (hepatomegaly)
Failure to thrive
Delayed motor skills
Progressive muscle weakness
Enlarged heart (cardiomegaly)
Serious breathing problems
Progressive muscle weakness, especially in the legs and trunk
As with any rare disorder, differentiating Pompe disease from other conditions, like spinal muscular atrophy, hypothyroidism, or muscular dystrophy, can be challenging. Pompe disease should be seriously considered by physicians if signs and symptoms suggest progressive muscular degeneration. Once a physician is suspicious of Pompe disease, GAA enzyme activity should be measured as soon as possible.
Since 2014, newborns have been screened for Pompe disease, and this has eliminated many delayed diagnoses of the condition.
The incidence of Pompe disease is approximately 1 in every 40,000 births, but this number may change as newborn screening identifies more children with this condition.
Management of Pompe disease requires coordinated efforts from a group of specialists with experience in treating neuromuscular disorders. Intense research and planning are necessary to effectively treat patients, and genetic counseling is vital for all parties involved: patients, families, and caregivers alike.
In 2006, the US Food and Drug Administration approved Sanofi Genzyme’s Lumizyme (alglucosidase alfa) for the treatment of all patients with Pompe disease. Treatment consists of an intravenous infusion of alpha-glucosidase, a recombinant human acid, that is administered every 2 weeks and essentially replaces the missing GAA enzyme in the bloodstream.
Aside from Lumizyme, there are several supportive therapies that can be deemed helpful to patients with Pompe disease. Respiratory support is likely necessary, with mechanical ventilation, via a BiPAP or volume ventilator, often used by patients, especially at night. Mechanical ventilation support can be had through either invasive or noninvasive techniques and depends on the specific needs of the patient.
Physical therapy, speech therapy, and occupational therapy are other common forms of treatment for Pompe disease. And although certain orthopedic symptoms, like contractures or spinal deformity, may require surgery, patients may find that orthopedic devices, like braces, help, too.
In Pompe disease, the muscles required to chew and swallow could progressively deteriorate. Because of this, the implementation of a specialized, high-calorie diet, may be required. Infants and children, however, may require a feeding tube.
Pompe disease served as the basis for the Harrison Ford/Brendan Fraser film, “Extraordinary Measures.” The movie is based on the story of John Crowley who used his entrepreneurial and pharmaceutical executive background to find a treatment for 2 of his children, Megan and Patrick, who had infantile-onset Pompe disease. His efforts were instrumental in getting Lumizyme approved. Today, he is chairman and CEO of Amicus Therapeutics, a company focused on developing treatments for a variety of rare conditions.
The International Pompe Association (IPA; worldpompe.org) is a collection of Pompe disease patient groups from around the world. It aims to help share experiences and knowledge across the internet, and serves as the coordinator for activities that might interest those affected by this rare condition. Annually, the group encourages folks from around the world to recognize and celebrate April 15 as International Pompe Day. With the slogan “Together, We Are Strong,” IPA intends to show the world just how strong the Pompe community is, both in numbers and passion.
The United Pompe Foundation (unitedpompe.myshopify.com) is a US-based patient organization that assists families with medical costs and other expenses that may not be covered, or fully covered, by insurance.