Understanding Pompe Disease

Pompe disease is a genetically inherited metabolic disorder caused by a GAA gene mutation resulting  in the lack of production of an enzyme, acid alpha glucosidase, that is critical for the breakdown and storage of glycogen in the body’s cells. This breakdown of glycogen occurs in a specific structure in the cells called a lysosome. When this breakdown does not happen normally, glycogen builds up within the lysosome causing it to swell. This accumulation of glycogen throughout the body eventually causes damage, especially to the heart and skeletal muscles.1

Patient education for Pompe disease depends on which type of the disease the patient has. There are 3 major types of Pompe disease: classic infantile-onset, non-classic variant of infantile-onset, and late-onset. Classical infantile-onset is diagnosed within the first 2 months of life and sometimes may be apparent in utero. Non-classic infantile-onset is diagnosed within the first year of life. Patient education for the infantile forms of the disease is more beneficial for the caregivers of the baby born with Pompe disease. Late-onset Pompe disease is diagnosed anywhere from age 1 through adulthood.2 In general, later disease onset indicates slower disease progression and longer life expectancy.3 Consequently, patients who are diagnosed with the late-onset form of the disease may benefit from therapeutic, dietary, and exercise recommendations to slow disease progression. 

Treatment

The infantile forms of Pompe disease are the most severe due to the complications associated with difficulty breathing and heart failure. Without proper diagnosis and immediate early treatment with enzyme replacement therapy (ERT), this form of the disease is typically fatal within the first year of life due to heart failure.3 It is critical that Pompe disease in infants is quickly diagnosed and ERT initiated prior to onset of severe symptoms to be effective in prolonging life. 

For individuals diagnosed with late-onset Pompe disease, doctors may recommend support therapies in addition to ERT. Physical therapy, occupational therapy, and speech therapy may improve overall muscle strength and caloric intake.3 Muscle weakness contributing to breathing difficulties must be assessed early using pulmonary function tests to determine the need for assistive breathing devices such as mechanical ventilators.3 Pulmonary rehabilitation may also be a viable treatment option to assist in strengthening the respiratory muscles and to delay or reduce the need for mechanical ventilation.4

Diet 

Babies with infantile-onset Pompe disease may have failure to thrive due to muscle weakness resulting in suckling and swallowing feeding difficulties.1 These infants may require tube feeding to provide adequate caloric intake.5 When making difficult decisions on behalf of their baby, parents of these infants must consider the severity of their baby’s disease and understand that most infants do not survive past the first year of life due to respiratory or heart failure. With this knowledge of disease progression, parents may elect not to pursue tube feeding.5 

Loss of lean muscle mass is common in Pompe disease. Evidence supports use of a high protein diet combined with exercise to slow this progressive deterioration. The breakdown of macronutrients for the recommended modified diet includes 25% to 30% proteins, 30% to 35% carbohydrates, and 35% to 40% fat. Consumption of carbohydrates should occur in small, frequent portions spaced throughout the day. This reduces rapid accumulation of glycogen from breakdown of carbohydrates, while simultaneously deterring hypoglycemia.6 

Smaller, more frequent meals throughout the day are also recommended to combat constipation, reduce acid reflux, and aid digestion. Sitting upright for 1 to 2 hours following meals may reduce or help avoid acid reflux. Staying well-hydrated and eating a high fiber diet may minimize or prevent constipation.6

Meat, fish, eggs, and dairy products are all protein-rich food sources of the amino acid, alanine, which plays an important role in glucose metabolism. Some researchers recommend that individuals with Pompe disease take an alanine supplement in addition to dietary sources.6 Working with a registered dietician may ensure that patients with Pompe disease maintain a well-balanced diet, which affects their overall health and well-being. 

If patients are able to swallow solid foods, ensuring that these foods are chopped into smaller pieces or mashing the food and moistening dry foods with sauces to ease swallowing. Thin liquids may be hard to swallow, so use of thickening agents like cornstarch or rice cereal may make swallowing these liquids easier.6

Even in late-onset Pompe disease, patients may not be able to ingest enough food by mouth if the muscles involved in swallowing are impacted by disease progression. These individuals may require surgical opening through the stomach wall to place gastronomy or G-tubes or placement of a nasogastric tube (NG tube) through the nose down the throat into the stomach for feedings.6

Exercise

Working with a physical therapist, speech language pathologist, and pulmonary rehabilitation therapist may build muscle tone and strength and slow the progression of skeletal muscle decline including muscles used in swallowing and respiration.3,4,7 

Exercise training including aerobic conditioning, resistance training, and core stabilization improves endurance, body composition, oxygen uptake capacity, and functional muscle strength. This combination of exercises was proven in a study to be a safe, beneficial adjuvant therapy in patients with Pompe disease.7

Genetic Counseling

Parents of children with Pompe disease should be informed of the autosomal-recessive nature of the disease and the potential for 25% of subsequent pregnancies to result in the disease. Other family members must be made aware of the genetic inheritance of this disease. Molecular genetic testing is encouraged for at-risk family members to identify carriers of genetic mutations.8 

Parents may elect to perform prenatal testing. Chorionic villus sampling (CVS) and amniocentesis may identify fetal GAA enzyme activity. CVS may allow for prenatal diagnosis of Pompe disease as early as 10 weeks’ gestation.8

Patient Resources

There are several patient-oriented organizations that provide information on clinical trials as well as financial, educational, and medical resources for those newly diagnosed or managing Pompe disease. These include the International Pompe Association at https://www.worldpompe.org; United Pompe Foundation at http://www.unitedpompe.com, Pompe Disease News at https://pompediseasenews.com, and Pompe Resources for Patients and Caregivers at https://www.pompe.com/pc/resources.

References

  1. Pompe disease family education booklet. Michigan Medicine at the University of Michigan: Division of Pediatric Genetics Metabolism and Genomic Medicine. Accessed July 16, 2021.
  2. Defendi GL. Genetics of glycogen-storage disease type II (pompe disease): background. Medscape. Published online March 2, 2021. Accessed July 16, 2021.
  3. Subramaniam V. How does pompe disease affect life expectancy? Pompe Disease News. Accessed July 16, 2021. 
  4. Fernández C, Rosso R. Role of respiratory rehabilitation in pompe disease: a case report. Journal of Neuromuscular Diseases. 2015; 2:S16-S17. doi:10.3233/JND-159016
  5. Defendi GL. Genetics of glycogen-storage disease type II (pompe disease) treatment and management: medical care, consultations, diet. Medscape. March 2, 2021. Accessed July 16, 2021.
  6. Walker M. Pompe disease and diet. Pompe Disease News. Accessed July 16, 2021.
  7. van den Berg LEM, Favejee MM, Wens SCA, et al. Safety and efficacy of exercise training in adults with pompe disease: evaluation of endurance, muscle strength and core stability before and after a 12 week training program. Orphanet J Rare Dis. 2015; 10:87. doi:10.1186/s13023-015-0303-0
  8. Defendi GL. Genetics of glycogen-storage disease type II (pompe disease) follow-up: further outpatient care, complications. Medscape. March 2, 2021. Accessed July 16, 2021. 

Reviewed by Debjyoti Talukdar, MD, on 7/27/2021.

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