Understanding McArdle Disease
McArdle disease is a rare, metabolic condition that is genetic. It results from changes in your DNA, called mutations, that affect your body’s ability to provide muscles with the energy they need to function. People living with McArdle disease generally experience muscle cramps/pain during regular activities and exercise. McArdle’s is also known as Glycogen Storage Disease Type 5 (GSD V).
Everyone experiences the disease differently. Symptoms can range from mild and manageable to severe and life-threatening.
Our bodies make, store and access energy. We convert the foods we eat into a simple sugar called glucose. If we have more glucose than we need, these molecules join together to form glycogen which can be stored in our muscles.
When we need energy, an enzyme called phosphorylase (or myophosphorylase) breaks down the stored glycogen. People with McArdle disease have inactive phosphorylase, so their muscles cannot access the stored glycogen. Without the energy they need, muscles cramp and fatigue during exercise.
McArdle disease is a recessive genetic disorder meaning the mutated gene is inherited from both mother and father. It is important for people to know if they carry the gene when it comes to family planning. Carriers will pass the abnormal gene on to their child(ren). If both parents are carriers and pass the abnormal gene on to the child, that child will have McArdle disease.