One of the glycogen storage diseases that develops because of a mutation in the gene for muscle phosphorylase; characterized by exercise intolerance.
McArdle disease, or glycogen storage disease Type V, is an autosomal recessive metabolic disorder that results in a defect in glycogen breakdown in skeletal muscle tissue. The breakdown of glycogen is necessary to create the energy that is especially needed during exercise. McArdle disease is characterized by a lack of the enzyme muscle glycogen phosphorylase. The primary store of glucose in the muscle tissue is in glycogen, and muscle glycogen phosphorylase acts as a catalyst in the degradation of glycogen into glucose. Without the capacity to break down glycogen, muscle tissue receives insufficient energy, resulting in fatigue and pain from only minimal activity.
One of the glycogen storage diseases (type V) in which there is an abnormal accumulation of glycogen in muscle tissue due to deficiency of myophosphorylase B. Symptoms include pain, fatigability, and muscle stiffness after prolonged exertion.
An uncommon genetic disorder marked by muscular rigidity and distressing spasms that intensify with physical effort and persist afterward. The root cause lies in the insufficiency of an enzyme within muscle cells responsible for catalyzing the conversion of the carbohydrate glycogen into the basic sugar glucose. This deficiency leads to an accumulation of glycogen and diminished glucose levels in the muscles. Consequently, muscle damage occurs, giving rise to myoglobinuria (the appearance of muscle cell pigments in urine), which can potentially lead to kidney failure.
While there is no cure, symptoms can be alleviated by consuming glucose or fructose prior to engaging in physical activity.