Glycogenosis type V is one of the glycogen storage diseases. What this means is that there is an inborn error of metabolism. It is an autosomal recessive metabolic disorder. Glycogenosis type V is evidenced by a deficiency in glycogen debranching enzymes.
Glycogenosis type V is a rare disorder. It takes place in around 1 out of every 100,000 live births in the United States.
Glycogenosis type V is a genetically linked metabolic disorder involving the enzymes that regulate glycogen metabolism. This is in common with other glycogen storage diseases. These enzymes affect synthesis or the processing of glycogen breakdown within your liver, ahaha muscles and other cell types. The process is halted if any one of these enzymes is faulty and does not finish its step. A different enzyme is involved in each step of the process. The type of glycogen storage disease that you have is determined by which particular enzyme is defective.
Glycogenosis type V is marked by a problem with glycogen storage in your body. There is an abnormal build up of glycogen in your muscle tissue. Glycogenosis type V usually starts in early childhood.
Glycogenosis type V is an hereditary (inherited) or genetic condition. As mentioned at the beginning, the pattern of inheritance is what is known as autosomal recessive. This means that you have to inherit a defective (mutated) gene from each one of your parents in order to have the possibility of having glycogenosis type V.
The dominant form of the disorder is rare. Glycogenosis type V is caused by a deficiency of myophosphorylase. This is the muscle isoform of the enzyme glycogen phosphorylase. Myophosphorylase helps break down glycogen into glucose so that it can be used within your muscle cells.
There are several signs and symptoms that you may experience that may be an indication that you have glycogenosis type V. Most of these signs and symptoms are related to exercise. Possible signs and symptoms are:
- Painful cramps
- Early fatigue
- Exercise intolerance with myalgia (muscular pain)
- Weakness of exercising muscles
- Myoglobinuria (the presence of myoglobin in your urine).
You may show substantial muscle loss and progressively increasing weakness as you age. The signs and symptoms of many people get worse after middle age due to muscle wasting.