What is Type V Glycogenosis (McArdle Disease, Myophosphorylase Deficiency)?
McArdle disease is a muscle variant of glycogenosis, in which all pathological signs are noted only in muscle tissue.
Causes of Type V Glycogenosis (McArdle Disease, Myophosphorylase Deficiency)
The type of inheritance is autosomal recessive.
Pathogenesis during Type V Glycogenosis (McArdle Disease, Myophosphorylase Deficiency)
Pathogenesis is based on a decrease in muscle glycogen phosphorylase activity, which makes up about 5% of all soluble muscle proteins. The gene of this enzyme is localized in the region of chromosome I lql3. The main type of mutapia is single nucleotide substitutions. Majority is considered a nonsense mutation in the 49 codon of the first exon.
Symptoms of Type V Glycogenosis (McArdle Disease, Myophosphorylase Deficiency)
The first signs of the disease occur in childhood or adolescence and are characterized by the appearance of painful muscle cramps after exercise, which disappear during relaxation. Muscle cramps are accompanied by severe muscle tightening. Quite often, during tonic cramps, pronounced autonomic symptoms can be observed: increased sweating, tachycardia, blanching of the skin. As the disease progresses, contractures of large joints can form.
Diagnosis of Type V Glycogenosis (McArdle Disease, Myophosphorylase Deficiency)
Diagnosis of the disease includes a clinical examination, determination of muscle glycogen phosphorylase activity in a muscle fiber biopsy. To confirm the diagnosis, a molecular genetic analysis is performed to detect mutations in the gene of this enzyme.
Treatment of Type V Glycogenosis (McArdle Disease, Myophosphorylase Deficiency)
The treatment is symptomatic.
Prevention of Type V Glycogenosis (McArdle Disease, Myophosphorylase Deficiency)
Prevention is not developed. To prevent the birth of a child with glycogenosis in families where there were similar patients, medical and genetic counseling is carried out.