Glycogen storage disease type IV the gene but show no symptoms of the disease. It affects 1 in 800,000 individuals worldwide, with 3% of all Glycogen Storage Diseases being type IV. It is a result of the absence of the glycogen branching enzyme, which is critical in the production of glycogen. This leads to very long unbranched glucose chains being stored in glycogen. The long unbranched molecules have a low solubility which leads to glycogen precipitation in the liver. These deposits subsequently build up in the body tissue, especially the heart and liver. The inability to breakdown glycogen in muscle cells causes muscle weakness. The
Equine exertional rhabdomyolysis cell membranes may then be damaged if the horse is forced to continue work, which allows muscle enzymes and myoglobin to leak into the bloodstream. The body builds up a store of glycogen from converted carbohydrates in muscle cells. Glycogen, a fuel used by muscles for energy, is depleted during work and restocked when a horse rests. Oxygen-carrying blood metabolizes glycogen, but the blood can not flow fast enough to metabolise the excess stored glycogen. The glycogen that is not metabolized aerobically (by the oxygenated blood) must then be metabolized anaerobically, which then creates the cell waste products and heat,