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McArdle disease
Glycogen storage disease type V (GSDV); Myophosphorylase deficiency; Muscle glycogen phosphorylase deficiency; PYGM deficiency
McArdle disease is a rare inherited condition in which the body is not able to break down glycogen. Glycogen is an important source of energy that is stored in all tissues, especially in the muscles and liver.
McArdle disease is also called type V glycogen storage disease.
Causes
McArdle disease is caused by a flaw in the gene that makes an enzyme called glycogen phosphorylase. As a result, the body cannot break down glycogen in the muscles.
Enzyme
Enzymes are complex proteins that cause a specific chemical change in all parts of the body. For example, they can help break down the foods we eat ...
The disease is an autosomal recessive genetic disorder. This means that you must receive a copy of the nonworking gene from both parents. A person who receives a nonworking gene from only one parent usually does not develop this syndrome. A family history of McArdle disease increases the risk.
Autosomal recessive
Autosomal recessive is one of several ways that a trait, disorder, or disease can be passed down through families. An autosomal recessive disorder me...
Symptoms
Symptoms usually start during early childhood. But, it may be difficult to separate these symptoms from those of normal childhood, and diagnosis may not occur until a person is over 20 or 30 years old.
- Burgundy-colored urine (myoglobinuria)
- Fatigue
- Exercise intolerance, poor stamina
- Muscle cramps
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Muscle pain
Muscle pain
Muscle aches and pains are common and can involve more than 1 muscle. Muscle pain also can involve ligaments, tendons, and fascia. Fascia are the s...
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- Muscle weakness
Exams and Tests
The following tests may be performed:
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Electromyography (EMG)
Electromyography (EMG)
Electromyography (EMG) is a test that checks the health of the muscles and the nerves that control the muscles.
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Lactic acid in blood
Lactic acid in blood
Lactic acid is mainly produced in muscle cells and red blood cells. It forms when the body breaks down carbohydrates to use for energy when oxygen l...
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MRI
MRI
A magnetic resonance imaging (MRI) scan is an imaging test that uses powerful magnets and radio waves to create pictures of the body. It does not us...
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Muscle biopsy
Muscle biopsy
A muscle biopsy is the removal of a small piece of muscle tissue for examination.
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Myoglobin in urine
Myoglobin in urine
The myoglobin urine test is done to detect the presence of myoglobin in urine. Myoglobin can also be measured with a blood test.
Read Article Now Book Mark Article - Plasma ammonia
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Serum creatine kinase
Serum creatine kinase
Creatine phosphokinase (CPK) is an enzyme in the body. It is found mainly in the heart, brain, and skeletal muscle. This article discusses the test...
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Treatment
There is no specific treatment.
The health care provider may suggest the following to stay active and healthy and prevent symptoms:
- Be aware of your physical limitations.
- Before exercising, warm up gently.
- Avoid exercising too hard or too long.
- Eat enough protein.
Ask your provider if it's a good idea to eat some sugar before exercising. This may help prevent muscle symptoms.
If you need to have surgery, ask your provider if it's OK for you to have general anesthesia.
Support Groups
The following groups can provide more information and resources:
- Association for Glycogen Storage Disease: www.agsdus.org
- McArdlesDisease.org: mcardlesdisease.org
Outlook (Prognosis)
People with McArdle disease can live a normal life by managing their diet and physical activity.
Possible Complications
Exercise may produce muscle pain, or even a breakdown of skeletal muscle ( rhabdomyolysis ). This condition is associated with burgundy-colored urine and a risk for kidney failure , if it is severe.
Rhabdomyolysis
Rhabdomyolysis is the breakdown of muscle tissue that leads to the release of muscle fiber contents into the blood. These substances are harmful to ...
Kidney failure
Acute kidney failure is the rapid (less than 2 days) loss of your kidneys' ability to remove waste and help balance fluids and electrolytes in your b...
When to Contact a Medical Professional
Contact your provider if you have repeated episodes of sore or cramped muscles after exercise, especially if you also have burgundy or pink urine.
Consider genetic counseling if you have a family history of McArdle disease.
References
Kishnani PS, Chen, YT. Defects in metabolism of carbohydrates. In: Kliegman RM, Stanton BF, St Geme JW, Schor NF, eds. Nelson Textbook of Pediatrics . 20th ed. Philadelphia, PA: Elsevier; 2015:chap 87.
Weinstein DA. Glycogen storage diseases. In: Goldman L, Schafer AI, eds. Goldman's Cecil Medicine . 25th ed. Philadelphia, PA: Elsevier Saunders; 2016:chap 207.
Review Date: 10/27/2015
Reviewed By: Chad Haldeman-Englert, MD, FACMG, Fullerton Genetics Center, Asheville, NC. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.
