What is the Difference Between McArdle Disease and Pompe Disease

McArdle disease and Pompe disease are two different types of glycogen storage diseases. Glycogen storage disease (GSD) is a rare genetic condition. It is caused by the body not being able to store or break down glycogen properly. GSDs can have different forms and subtypes. There are more than 13 different types of GSD. The most common types are types I, II, III, IV, and V.

The key difference between McArdle disease and Pompe disease is their nature. McArdle disease is a type V glycogen storage disease that causes exhaustion, cramping, and muscle pain in everyday activities while Pompe disease is a II glycogen storage disease that causes progressive muscle weakness throughout the body and affects the various body tissues which include heart, skeletal muscles, liver, and nervous system.

CONTENTS

1. Overview and Key Difference
2. What is McArdle Disease 
3. What is Pompe Disease
4. Similarities – McArdle Disease and Pompe Disease
5. McArdle Disease vs Pompe Disease in Tabular Form
6. Summary – McArdle Disease vs Pompe Disease
7. FAQ: McArdle Disease and Pompe Disease

What is McArdle Disease?

McArdle disease is a type V glycogen storage disease. It is a rare genetic condition. McArdle disease happens when the body has a deficiency or complete lack of an enzyme called muscle glycogen phosphorylase (PYG) due to a mutation in PYGM gene. McArdle disease is inherited in an autosomal recessive pattern. This results in muscle cramps and weakness, especially during physical activity. This condition was first reported by Dr. Brian McArdle in 1951. The symptoms of this condition include getting tired during physical activity, muscle cramps, weakness, fatigue, muscle pain, and muscle stiffness.

Figure 01: McArdle Disease

McArdle disease can be diagnosed through family history, physical examination, creatinine kinase blood test, graded exercise stress test, muscle biopsy, and genetic testing. Furthermore, treatment options for McArdle disease include avoiding certain types of physical activity, moderate intensity graded aerobic exercise, physical therapy, and having a high carbohydrate eating plan.

What is Pompe Disease?

Pompe disease is also known as the glycogen storage disease type II. This disease results from a deficiency of a digestive enzyme called acid alpha-glucosidase (GAA) due to a mutation in the GAA gene. Due to the lack of GAA enzyme, the glycogen builds up in the lysosomes, which causes severe muscle damage. The symptoms of infantile Pompe disease include trouble eating, not gaining weight, poor head and neck control, breathing problems, rolling over and sitting up later than expected, enlarged thickened heart, enlarged liver, and enlarged tongue. Moreover, the symptoms of late-onset Pompe disease are feeling weak in the legs, trunk, and arms, shortness of breath, a big curve in the spine, an enlarged liver, an enlarged tongue, and a stiff neck.

Figure 02: Pompe Disease

Pompe disease can be diagnosed through family history, physical examination, blood test, and genetic testing. Furthermore, treatment options for infantile Pompe disease is enzyme replacement therapy by using lumizyme, myozyme and nexviazyme while treatment options for late-onset Pompe disease is enzyme replacement therapy using cipaglucosidase alfa-atga and miglustat.

Similarities Between McArdle Disease and Pompe Disease

1. McArdle disease and Pompe disease are two different types of glycogen storage diseases.
2. Both types are caused due to the body not being able to store or break down glycogen properly.
3. Both types are triggered by inherited gene mutations that cause enzyme deficiencies.
4. They can be diagnosed through family history, physical examination, blood test, and genetic testing.
5. They can be treated by giving specific medications.

Difference Between McArdle Disease and Pompe Disease

Definition

1. McArdle disease is a type V glycogen storage disease due to PYG enzyme deficiency.
2. Pompe disease is a type II glycogen storage disease due to GAA enzyme deficiency.

Cause

1. McArdle disease is caused by PYGM gene mutation.
2. Pompe disease is caused by GAA gene mutation.

Discovered by

1. McArdle disease was discovered by Dr. Brian McArdle in 1951.
2. Pompe disease was discovered by Dr.Joannes Cassianus Pompe in 1932.

Signs and Symptoms

1. The symptoms of McArdle disease include Brownish red urine, especially after activity, easily tiring during activity, with stiffness or weakness soon after starting the exercise, muscle cramping, muscle pain and lasting weakness in thigh or other muscles.
2. The symptoms of the infantile type include myopathy, hypotonia, hepatomegaly, heart defects, poor growth and weight gain, and respiratory difficulties; the symptoms of the late-onset type include myopathy, muscle cramping, extreme fatigue, gait abnormality, mobility difficulties, and respiratory difficulties.

Diagnosis

1. McArdle disease can be diagnosed by family history, physical examination, creatinine kinase blood test, graded exercise stress test, muscle biopsy, and genetic testing.
2. Pompe disease can be diagnosed by family history, physical examination, blood test, and genetic testing.

Treatment

1. McArdle disease can be treated by careful attention to a diet rich in carbohydrates, taking creatine supplements, eating or drinking prescribed amounts of sucrose before exercise, moderate, aerobic exercise plan and taking other medicines such as ACE inhibitors.
2. Pompe disease can be treated by enzyme replacement therapy (ERT), and additional supportive therapies that target specific symptoms and complications of the disease.

The following table summarizes the difference between McArdle disease and Pompe disease.

Summary – McArdle Disease vs Pompe Disease

Glycogen storage disease (GSD) is a rare genetic condition that changes the way the body breaks and stores glycogen. Glycogen storage disease is a hereditary condition. McArdle disease and Pompe disease are two different types of glycogen storage diseases. McArdle disease is a type V glycogen storage disease, while Pompe disease is a II glycogen storage disease. Moreover, McArdle disease causes exhaustion, cramping, and muscle pain in everyday activities due to PYG enzyme deficiency caused by PYGM gene mutation. Pompe disease causes progressive muscle weakness throughout the body and defects in other organs like the heart, liver, and nervous system due to GAA enzyme deficiency caused by GAAgene mutation. This is the summary of the difference between McArdle disease and Pompe disease.

FAQ: McArdle Disease and Pompe Disease

1. What are glycogen storage diseases?

• Glycogen storage disease (GSD) is the term used for a group of disorders that interfere with the body’s ability to break and store glycogen. Depending on the type of GSD a child has, glycogen may build up in the liver, in the muscles, or both.

2. What is the cause of McArdle’sMcArdle’s disease?

• McArdle disease is an inherited disease. It is caused by a mutation in the gene called PYGM, which is responsible for making the enzyme muscle phosphorylase. The muscle cells can’tcan’t make this enzyme. Therefore, they can’tcan’t break down glycogen into glucose.

3. What is the hallmark of McArdle disease?

• McArdle disease is an inherited genetic disorder that mainly affects skeletal muscles. It occurs due to the deficiency or absence of an enzyme called myophosphorylase. Symptoms of this condition are painful muscle cramps, weakness, and fatigue manifest during the physical activity. Furthermore, McArdle disease is treated through avoiding the types of physical activity that make the symptoms worse and having a high carbohydrate eating plan.

4. What are the symptoms of adult Pompe disease?

• The symptoms of adult onset Pompe disease include legs and trunk get steadily weaker, increasing difficulty walking, muscle pain, loss of ability to exercise, often falling, frequent respiratory infections, shortness of breath, headaches in the morning, tiredness during the day, unintended weight loss, difficulty swallowing, irregular heartbeat and increased difficulty hearing.

5. What is the enzyme deficiency in Pompe disease?

• Pompe disease happens because of a mutation in a gene known as GAA that helps make an enzyme called acid alpha-glucosidase. This enzyme breaks down a type of glucose called glycogen. When the enzyme is not made properly, glycogen builds up in the lysosomes which causes severe muscle damage.

 Reference:

1. “Pompe Disease.” Boston Children’s Hospital.
2. “McArdle Disease.” Cleveland Clinic.

Image Courtesy:

1. “Vacuolar myopathy mcArdle type V glcogenosis” By Jensflorian – Own work (CC BY-SA 3.0) via Commons Wikimedia
2. “Pompe vacuoles” By Jensflorian – Own work (CC BY-SA 3.0) via Commons Wikimedia

Related posts:

Difference Between Chlamydia and Gonorrhea Difference Between Cold Sore and Herpes What is the Difference Between Myositis and Rhabdomyolysis What is the Difference Between Hepatomegaly and Fatty Liver What is the Difference Between Underactive Thyroid and Hashimoto’s Disease