Pompe Disease and Other Genetic Disorders

Via Peters

Pompe disease is a rare genetic disorder that disables the heart and skeletal muscles.

The inherited disorder can develop at any age, although the often-fatal disorder has faster progression and greater disease severity in earlier onset diagnoses.

Pompe disease occurs in every 1 in 40,000 births and can sometimes be mistaken for other genetic diseases. That’s because Pompe disease has symptoms similar to those of other genetic conditions.

There are, however, certain distinctions that can help physicians determine if it’s Pompe disease or something else.

Here’s what you need to know about the symptoms of Pompe disease and how it compares to similar genetic diseases.

Pompe disease is an inherited disorder caused by a total absence of acid alpha-glucosidase, or GAA, an enzyme that helps break down glycogen in the body.

Since individuals with Pompe disease don’t have GAA activity in their bodies, they experience a rapid buildup of glycogen in their heart and skeletal muscles. This rapid buildup then contributes to a host of symptoms associated with Pompe disease.

Because it’s a rare disorder, Pompe disease often requires a team of specialists, including internists, neurologists, pediatricians, orthopedists, cardiologists, dietitians, and physical therapists to manage treatment.

Pompe disease treatment plans are based on self-descriptions or descriptions provided by a caregiver. They often include enzyme replacement therapy (ERT), which involves intravenous administration of the GAA enzyme. ERT can help extend the life expectancy for people with Pompe disease. However, the disorder has no known cure.

Supportive therapy, like physical or speech therapy, is also a common part of treating Pompe disease, particularly in those diagnosed with the infantile onset subtype. Speech therapy may be needed as weakened facial muscles may make it difficult to articulate speech. Difficulty swallowing and even breathing call for further therapies.

Symptoms of Pompe disease generally affect the heart and skeletal muscles.

People who have an infantile form of Pompe disease, which usually presents within the first three months of life, experience the most severe symptoms. These include:

  • rapidly progressive muscle weakness
  • diminished muscle tone
  • respiratory deficiency
  • hypertrophic cardiomyopathy, or abnormal thickening of the walls of the heart

When these symptoms are combined, they often result in cardio-respiratory failure within the first 2 years of life. Infants with Pompe disease will often have a large, protruding tongue and an enlarged liver. Their legs may rest in a frog position and feel firm to the touch.

Childhood and adult Pompe disease often sees progressive weakness in the arms and legs, which can affect mobility and balance. Progressive respiratory weakness can also occur from dysfunction of the diaphragm and muscles between the ribs.

Younger individuals with Pompe disease may also experience scoliosis, or an abnormal curvature of the spine. This typically occurs at puberty due to muscle weakness in the spinal area.

As a result, people with Pompe disease may require wheelchairs or ventilators.

Other symptoms of Pompe disease include:

  • chewing and swallowing difficulties
  • drooping upper eyelids
  • blood vessel abnormalities
  • urinary and digestive problems
  • increased respiratory tract infections

There are several genetic diseases that Pompe disease can be mistaken for.

Werdnig-Hoffman disease

Werdnig-Hoffman disease, or spinal muscular atrophy type 1 (SMA type 1), is a rare genetic disorder that can be confused with Pompe disease. Like Pompe disease, it’s characterized by progressive muscle weakness. Poor muscle tone is another symptom of Werdnig-Hoffman.

However, unlike Pompe disease, SMA type 1 doesn’t affect the heart — an important distinction.

Danon disease

Danon disease is another genetic disorder that can mimic symptoms of Pompe disease.

It also causes muscle weakness and cardiomyopathy, a disease of the heart muscle that can lead to heart failure. Because of this, men with Danon disease may need a heart transplant at some point in their lives.

The disease can cause intellectual disability as well, though the majority of associated cognitive deficits tend to be mild.

Neurological symptoms aren’t generally linked to Pompe disease.

Endocardial fibroelastosis

Endocardial fibroelastosis, which can occur as a result of genetics, affects the heart. This disease is characterized by a thickening of the muscular lining of the heart chambers due to an increase in supporting connective tissue and elastic fibers.

Like Pompe disease, individuals with endocardial fibroelastosis experience impaired heart and lung function. However, the reason behind the impaired function differs.

Facioscapulohumeral dystrophy

Facioscapulohumeral dystrophy (FSHD) can mimic some symptoms of childhood and adult Pompe disease. It includes weakness of upper arm muscles, face, and shoulders.

Limited movement of the lips and difficulty raising the arms over the head may lead a physician to perform a confirmatory diagnostic test on chromosome 4. The mutations that occur in Pompe disease are localized to chromosome 17.

Duchenne muscular dystrophy

Duchenne muscular dystrophy, or DMD, is a genetic muscle disorder that, like Pompe disease, includes muscle weakness. It often occurs in early childhood or infancy.

DMD is the result of changes or mutations of the DMD gene on the X chromosome. It typically causes individuals to develop cardiomyopathy and respiratory difficulties. In addition, muscles in the upper legs, upper arms, and pelvic area become weakened.

Molecular genetic tests, a thorough clinical evaluation, and a detailed patient history are all part of reaching a DMD diagnosis.

Becker muscular dystrophy

Becker muscular dystrophy is characterized by similar muscle weakness as seen in Duchenne muscular dystrophy but often occurs at a later age. People with this condition are often able to walk independently into their 20s.

Doctors reach a Becker muscular dystrophy diagnosis through a close assessment of a person’s physical symptoms, their family history, and testing that shows an elevated concentration of creatine kinase (CK) in the blood.

Pompe disease falls into a category of conditions known as glycogen storage diseases, which include changes in the way bodies use and store glycogen.

Other glycogen storage diseases that Pompe disease can sometimes be mistaken for are McArdle disease (GSD type V) and Hers disease (GSD type VI). McArdle disease, however, only affects the skeletal muscles, while Hers disease affects the liver.

Although some effects of Pompe disease can overlap with other genetic diseases, it’s important to keep a close eye on symptoms and their severity. This is the first step in obtaining an accurate diagnosis.

Consider making a list of all symptoms, when they occur, what causes them to worsen, and how they affect you. This is an important part of the patient analysis your doctor will perform.

You can also expect your doctor to take a blood sample to study and count the enzymes in your blood.

Several other tests are used to diagnose Pompe disease:

  • breathing tests to measure lung capacity
  • electromyography to measure how well the muscles work
  • MRIs (magnetic resonance imaging)
  • heart studies, including X-rays, electrocardiograms, and echocardiograms
  • sleep studies

Although Pompe disease is similar to some other genetic disorders, treatments differ, and it’s important to get an accurate diagnosis for proper care and improved quality of life.

https://www.healthline.com/health/why-pompe-disease-can-be-mistaken-for-other-genetic-diseases

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