Glycogen Storage Disease Type V, also known as McArdle disease, is a rare genetic disorder characterized by the deficiency of myophosphorylase enzyme, which is responsible for breaking down glycogen into glucose in muscle cells. This impairment leads to the inability of affected individuals to release glucose from stored glycogen in muscles during physical activity.
Symptoms of Glycogen Storage Disease Type V typically appear in late childhood or early adulthood. The most common manifestation is exercise intolerance, whereby affected individuals experience muscle pain, cramps, and fatigue during physical exertion. Additionally, strenuous exercise may result in the breakdown of muscle fibers, leading to the release of muscle enzymes, such as creatine kinase, into the bloodstream.
Diagnosis of Glycogen Storage Disease Type V involves a combination of evaluating symptoms, conducting genetic testing, and measuring enzyme levels in muscle tissue or blood samples. Genetic counseling is recommended for affected individuals and their families to understand the inheritance pattern and potential risks.
Management of Glycogen Storage Disease Type V involves avoiding activities that induce muscle damage, which can be achieved through careful exercise planning, warm-up routines, and gradual intensification of physical activity. Consuming a diet rich in carbohydrates, particularly prior to exercise, can also help provide alternative fuel sources for muscles. In some cases, supplementation with oral glucose or intravenous glucose may be necessary during intense exercise or in emergency situations.
While there is currently no cure for Glycogen Storage Disease Type V, individuals can lead relatively normal lives by following strict management strategies and receiving regular medical follow-ups to monitor muscle function and overall health. With proper care, the prognosis for people with Glycogen Storage Disease Type V is usually favorable.
