Pompe Disease

What is Pompe Disease?  

Pompe Disease, also called Glycogen Storage Disease Type II (GSD II), is a genetic disorder that leads to problems with storing a complex sugar called glycogen in cells. The buildup of glycogen can cause muscles to not work properly. 

Pompe disease is part of a group of diseases called lysosomal storage disorders (LSDs). 

Pompe disease is divided into two types based on age of when symptoms started and the severity of symptoms. The two types of the disease are:

  • Infantile-onset Pompe disease (IOPD) – This type appears within the first year of life (usually within the first few weeks or months) and includes heart disease.
  • Late-onset Pompe disease (LOPD) – This type often appears later in childhood, adolescence or adulthood and does not include heart disease, though some LOPD can present within the first year of life.

What are symptoms of Pompe Disease?

IOPD begins within the first few months of life. Babies usually show signs of muscle weakness and have heart problems. Without treatment, this form of Pompe disease can lead to death within the first year of life.

Other symptoms of IOPD include:

  • Weak sucking and swallowing muscles that make eating difficult. This can lead to problems gaining weight. 
  • Overall muscle weakness and poor muscle tone. This can cause a “floppy” appearance and problems with movement. 
  • Weak breathing muscles that can cause difficulty breathing. The weakness also increases risk for infections. These muscles are located below and near the ribs (diaphragm).
  • Heart problems – Babies usually have larger hearts (cardiomegaly) and thicker heart muscle (cardiomyopathy). These heart problems can cause heart failure.

LOPD can begin any time from around the age of 1 year old through adulthood. It is less severe because there are usually no heart problems and muscle weakness occurs more gradual over time. Symptoms include increased muscle weakness, especially in the legs, and breathing problems. 

Other symptoms of LOPD include:

  • Eating difficulties – Weak jaw and swallowing muscles that can make eating difficult. This can lead to trouble gaining or maintaining weight. 
  • Muscle weakness – Gradual weakening of leg and hip muscles that can cause walking difficulties and possible need for support.
  • Breathing concerns – Weakness of the muscles needed to breathe that can cause difficulty breathing, higher risk for infections, low energy and sleep difficulties. 

How is Pompe disease diagnosed?  

  • Enzyme Testing: To make a diagnosis of Pompe disease, your doctor measures the level of acid alpha glucosidase enzyme activity. Usually, the level of activity is measured by taking a small amount of blood, however, skin and muscle can also be used. People with Pompe disease will show low levels of acid alpha glucosidase enzyme activity.
  • Genetic Testing: Genetic testing is also important for diagnosing Pompe disease. Your doctor will test the GAA gene to look for changes or missing pieces of the gene that cause the gene not to work. The GAA gene is the only gene that causes Pompe disease. The testing includes a small blood sample. Once your doctor knows the exact change in the GAA gene, they can better understand what type of Pompe disease an individual may have.  
  • Newborn Screening for Pompe disease: Newborn screening (NBS) is the process of testing newborn babies for some serious, but treatable, conditions. Newborn screening involves a heel prick for blood testing. For Pompe disease, a positive newborn screen alone does not mean the baby has the disease. Further testing is needed to diagnose Pompe disease. Michigan has been screening for Pompe disease since August 2017. 

How common is Pompe Disease?

In the United States, it is estimated that 1 in 40,000 people have Pompe disease (including both IOPD and LOPD).

Pompe Disease treatment

Currently, there is no cure for Pompe disease. However, there are ways to treat and manage the disease. Enzyme replacement therapy (ERT) is a treatment that can help with the breakdown of glycogen. ERT is a medical treatment that replaces the missing enzyme, acid alpha glucosidase, in patients with Pompe disease. ERT is given to patients by a slow intravenous infusion (IV) every other week for their lifetime.  ERT improves muscle weakness, heart muscle, motor skills, and breathing problems. 

Why choose Michigan Medicine?  

Michigan Medicine has a Lysosomal Storage Disorder Clinic dedicated to taking care of patients, both pediatric and adults, with Pompe disease and other lysosomal storage disorders. Our team includes six biochemical geneticists trained to care for patients with Pompe disease. Additionally, the team works closely with other specialists within the hospital to provide the best multidisciplinary care possible. 

Michigan Medicine is one of two centers that follow up on abnormal newborn screening for Pompe disease in the state of Michigan. Here, we have a dedicated genetic counselor to help patients navigate the process of completing testing and coordinating treatment and management.

Make an appointment

To schedule an appointment or speak with the genetic counselor, please contact 734-764-0579.