What is myophosphorylase deficiency?
Myophosphorylase (muscle phosphorylase) deficiency (MIM #232600), historically known as McArdle disease, is the most common glycogen storage disease (GSD) affecting the muscle (figure 1) [1]. The GSDs are generally categorized by number according to the chronology of recognition of the responsible enzyme defect.
Which enzyme is deficient in McArdle disease?
McArdle disease is an inherited disease. It results from changes (mutations) in the gene for the enzyme muscle phosphorylase. Your muscle cells can’t make this enzyme. So they can’t break down glycogen into glucose.
Why is lactate low in McArdle’s disease?
It is generally assumed that patients with McArdle disease do not produce lactate during exercise. Because glycogen breakdown is completely blocked whereas oxidation of extramuscular glucose supplies is preserved, these patients provide an opportunity to selectively study glucose metabolism.
Is McArdle disease a metabolic disease?
McArdle disease, also known as glycogen storage disorder type V, is an inborn metabolic disorder characterized by a deficiency or complete absence of an enzyme called glycogen phosphorylase (or myophosphorylase). This disease is inherited in an autosomal recessive pattern and mainly affects skeletal muscles.
What is Anderson’s disease?
Andersen disease is also known as glycogen storage disease (GSD) type IV. It is caused by deficient activity of the glycogen-branching enzyme, resulting in accumulation of abnormal glycogen in the liver, muscle, and/or other tissues.
Where is myophosphorylase found?
Myophosphorylase is one of three related enzymes called glycogen phosphorylases that break down glycogen in cells. Myophosphorylase is found only in muscle cells, where it breaks down glycogen into a simpler sugar called glucose-1-phosphate.
Is McArdle’s disease progressive?
In rare cases, McArdle disease is so severe it causes congenital weakness and progressive respiratory failure.
What is the primary pathological characteristic of McArdle disease?
McArdle disease, also known as glycogen storage disease type V (GSDV), is characterized by exercise intolerance, the second wind phenomenon, and high serum creatine kinase activity. Here, we recapitulate PYGM mutations in the population responsible for this disease.
What causes Anderson’s disease?
Can you have a baby with Addison’s disease?
In truth, before the advent of steroid treatment, Addison’s did cause very severe complications in pregnancy. With currently available treatment, women with Addison’s may have a slightly higher risk for preterm delivery, small babies and c-sections, but most will have healthy pregnancies and healthy babies.
What is Phosphofructokinase deficiency?
Phosphofructokinase (PFK) deficiency is a glycogen storage disorder (GSD). It is rare and is inherited as an autosomal recessive disorder. There is a mutation in the gene encoding muscle PFK on chromosome 12. There is also reduced activity of red cell PFK.
What is the function of Phosphoglucomutase?
Introduction. Phosphoglucomutase (PGM) (EC 5.4. 2.21) is an evolutionarily conserved and well characterized enzyme that catalyzes the interconversion of glucose 1-phosphate and glucose 6-phosphate via a glucose 1,6-diphosphate intermediate, making it a key enzyme in both glycolysis and gluconeogenesis.
What causes phosphorylase deficiency ( McArdle disease )?
The disease is caused by a genetic defect in the phosphorylase (also known as myophosphorylase) enzyme, which affects the breakdown of glocogen, the stored form of glucose (sugar). For more, see Causes/Inheritance. What is the progression of phosphorylase deficiency?
Is the phosphorylase stain normal for McArdle disease?
Phosphorylase stain: Normal Type II fibers: Darker than type I Phosphorylase stain: McArdle disease Myophosphorylase deficiency Muscle fibers stain yellow PAS stain: McArdle disease
How is phosphorylase deficiency related to glycogenosis?
Phosphorylase deficiency (McArdle disease) What is phosphorylase deficiency (McArdle disease, myophosphorylase deficiency, glycogenosis type 5)? This disease is one of a group of metabolic muscle diseases that interferes with the processing of food (in this case, carbohydrates) for energy production.
How does phosphorylase deficiency cause muscle cramps?
Phosphorylase deficiency causes exercise intolerance, such as cramps, muscle pain and weakness, shortly after beginning exercise. This disease is one of a group of metabolic muscle diseases that interferes with the processing of food (in this case, carbohydrates) for energy production.
