A metabolic disorder that is characterized by a deficiency of glycogen synthase (GYS2) and not resulting in the storage of extra glycogen
Glycogenosis refers to a group of metabolic disorders due to the improper metabolism of glycogen. It involves certain enzymes that have become defective or deficient and therefore affected glycogen metabolism. The outcome is the excessive deposition of glycogen in cells. There are different types of glycogen storage disease. Type 0 glycogenosis is one of them. It is characterized by a deficiency of glycogen synthase. Compared with other types of glycogenosis, the type 0 does not involve deposition of excess glycogen in the liver, in particular. There is a moderate decrease in glycogen stores in the liver. In humans, there are two isoforms of glycogen synthase. The first isoform, GYS1, is the form expressed in the skeletal and cardiac muscle whereas the second form, GYS2, is expressed in the liver. In type 0 glycogenosis, mutation in the gene coding for GYS2 affects the production of functional GYS2.1
Type 0 glycogenosis is inherited in an autosomal recessive pattern. This means that the individual has two copies of the defective gene and therefore manifests symptoms associated with the disease. A carrier of the disease would have only one copy of the defective gene and therefore may not show symptoms.
The common symptoms associated with type 0 glycogenosis are ketosis, lethargy, hypoglycemia, fatigue, and muscle cramping.
- glycogen synthetase deficiency
- glycogen storage disease type 0 (GSD-0)
1 Saadeh-Haddad, R. 2017. Glycogen-Storage Disease Type 0 (GSD-0) (Glycogen Synthetase Deficiency). Emedicine.net. Retrieved from ://emedicine.medscape.com/article/944467-overview#a4.