Glycogen Storage Disease Type V - Symptoms and Presentation

Symptoms and Presentation

The onset of this disease is usually noticed in childhood, but often not diagnosed until the third or fourth decade of life. Symptoms include exercise intolerance with myalgia, early fatigue, painful cramps, weakness of exercising muscles and myoglobinuria. Myoglobinuria, the condition where myoglobin is present in urine, may result from serious damage to the muscles, or rhabdomyolysis, where muscle cells breakdown, sending their contents into the bloodstream.

Patients may exhibit a “second wind” phenomenon. This is characterized by the patient’s better tolerance for aerobic exercise such as walking and cycling after approximately 10 minutes. This is attributed to the combination of increased blood flow and the ability of the body to find alternative sources of energy, like fatty acids and proteins. In the long term, patients may exhibit renal failure due to the myoglobinuria, and with age, patients may exhibit progressively increasing weakness and substantial muscle loss.

Patients may present at emergency rooms with severe fixed contractures of the muscles and often severe pain. These require urgent assessment for rhabdomyolysis as in about 30% of cases this leads to acute renal failure. Left untreated this can be life threatening. In a small number of cases compartment syndrome has developed, requiring prompt surgical referral.