Classification of glycogenases

Glycogen is a branched homopolymer of glucose, which has a "tree-like" structure. Glucose residues are connected by alpha (1- »4) -glycoside bond, and at the branching points - by alpha (1-, 6) -glycoside bond. Glycogen is stored in the liver and muscles. The glycogen of the liver serves primarily to maintain blood glucose levels, while in the muscles it is the source of hexose units used during glycolysis in the organ itself. There are 12 forms of glycogenosis, the most common of them in children - I, II, III, IX types, and in adults - V type. The total frequency of glycogenosis is 1:20 000 live births. Glycogenoses are divided into two large groups - with predominant liver damage and with a predominant lesion of muscle tissue. According to the accepted classification, each of the glycogenoses is assigned a number reflecting the sequence of their description.

Hepatic forms include glycogenosis I, III, IV, VI, hepatic variant IX and 0. Most of them are characterized by hepatomegaly, lowering of blood glucose level and growth retardation. Glycogenosis type I - the most severe form of this group, because it breaks not only the decomposition of glycogen, but also the synthesis of glucose from other sources (gluconeogenesis). Glycogenosis of type VI and hepatic form of type IX are the milder forms of diseases in which an insignificant decrease in glucose level is observed, liver sizes return to normal with age and the quality of life of patients practically does not suffer.

Hepatic forms of glycogenoses

Glycogenosis type I - synonyms: Girke's disease, glycogen storage disease type I (GSD I). Glycogenosis type I - a hereditary disease that manifests at an early age. Glycogenosis type I is divided into two forms - 1a and lb, which are caused by mutations in different genes and differ slightly clinically.

Glycogenosis type III - synonyms: amylo-1,6-glucosidase deficiency, Cory's disease, Forbes disease, glycogen storage disease type HI (GSD III). There are two clinical forms of the disease. In the majority of patients, generalized enzyme deficiency is observed (its activity is reduced in the liver, muscle tissue, leukocytes and fibroblasts of the skin) - type III glycogenesis; clinically it is manifested by myopathy and cardiomyopathy. Approximately 15% of the clinical manifestations are limited to liver damage - glycogenosis IIIb.

Glycogenosis type IV - synonyms: deficiency of the branching enzyme glycogen, deficiency of amylo 1,4: 1,6-glucan transferase, Andersen's disease, amylopectinosis, disease with polyglucoseans bodies, glycogen storage disease type IV (GSD IV). There are several forms that differ in age from the onset and clinical manifestations.

Glycogenosis type VI - synonyms: deficiency of glycogen phosphorylase, Gears disease, glycogen storage disease type VI (GSD VI).

Glycogenosis IX type - synonyms: deficiency of kinase phosphorylase, glycogen storage disease type IX (GSD IX). Glycogenosis IX type - a group of hereditary disorders of glycogen accumulation with different types of inheritance. According to the type of inheritance and clinical manifestations, six subtypes of the disease are distinguished:

• linked to the X-chromosome liver variant (XLG or GSD IXa) - the most common;
• combined hepatic and muscular variant (GSD IXb);
• autosomal recessive hepatic variant (GSD IXc);
• linked to the X-chromosome muscle version (GSD IXd);
• autosomal recessive muscular variant (GSD IXe);
• with defeat of the heart muscle (GSD IXf). Type of inheritance which is not installed.

Glycogenosis of type 0 - synonyms: glycogen synthase deficiency, glycogen storage disease type 0 (GSD 0). This disease does not observe the accumulation of glycogen in the liver, but since the symptoms of the disease are similar to other glycogenases, it is referred to this group, although this is a violation of not the decay, but the synthesis of glycogen.

Muscular forms of glycogenoses

At rest in the muscle tissue, the fatty acids predominantly serve as the energy source. During exercise, glucose is also used, most of which comes from liver glycogen. With intense physical exertion, the main source of energy is anaerobic glycolysis as a result of the breakdown of muscle glycogen. Defects of enzymes involved in these metabolic pathways affect the muscular function.

Glycogenosis type II - synonyms: Pompe disease, acid deficiency aD-glucosidase, maltose deficiency, glycogen storage disease type II (GSD II). Glycogenosis AND type - an autosomal recessive disease associated with a violation of glycogen exchange, related to muscle forms of glycogenoses, as well as to lysosomal accumulation diseases. This disease can be classified as neuromuscular pathology, metabolic myopathy or glycogenosis (Pompe's disease is the only glycogenosis in which the disorder of glycogen decomposition is associated with a defect in the function of lysosomes), and the infantile form of the disease is also referred to as cardiac pathology due to marked changes in the heart.

Type V glycogenesis is synonymous with: myophosphorylase deficiency, McArdle's disease, glycogen storage disease type V (GSD V).

Glycogenosis VII type - synonyms: deficiency of phospho-fructokinase (PFK), Tarui diseases, glycogen storage disease type VII (GSD VII).

Rare forms of muscle glycogenases

Glycogenosis IIb type - synonyms: Danone's disease. glycogen storage disease type lib (GSD lib). pseudo-Pompe disease.

Insufficiency of phosphoglycerate kinase.

Glycogenosis XI type - synonyms: glycogen storage disease type XI (GSD XI), insufficiency of lactate dehydrogenase.

G glycogenosis of X type - synonyms: deficiency of phosphoglycerate mutase (PGAM), glycogen storage disease type X (GSD X).

Glycogenosis XII type - synonyms: glycogen storage disease type XII (GSD XII), aldolase deficiency A.

Glycogenosis XIII type - synonyms: glycogen storage disease type XIII (GSD XIII), insufficiency (3-enolase.

[1], [2], [3], [4], [5], [6]