According to the most recent publications, 95 different mutations have been reported. 2021, Muscular Dystrophy Association Inc. All rights reserved. Cells form glucose-1-phosphate instead of glucose during glycogen breakdown because the polar, phosphorylated glucose cannot leave the cell membrane and so is marked for intracellular catabolism. Alternative names. If rhabdomyolysis is suspected, serum myoglobin, creatine kinase, lactate dehydrogenase, electrolytes and renal function will be checked. Mutations in the PYGL gene cause GSDVI. The two types of PhK deficiency are liver PhK deficiency(characterized by early childhood onset of hepatomegaly and growth … ©2021, Muscular Dystrophy Association Inc. All rights reserved. Ammonia levels may rise given ammonia is a by-product of the adenylate kinase pathway, an alternative pathway for ATP production. Researchers on metabolic diseases of muscle are making progress on a number of fronts, including: Muscular Dystrophy Association National Office, 800-572-1717 | ResourceCenter@mdausa.org. To learn more about the effect of diet in this disease, see What Not to Eat: Some consensus, much controversy about diet in three metabolic diseases. When the the Glycogen Synthase - Glycogen Phosphorylase complex is phosphorylated, which of the following events takes place? TERMS IN THIS SET (28) Glycogen Structure Aldohexose forms pyranose Monomer alpha-D-glucose Nonreducing Connected by … Glycogen storage disease type VI (GSD VI) is a type of glycogen storage disease caused by a deficiency in liver glycogen phosphorylase or other components of the associated phosphorylase cascade system. The associated enzyme deficiency was discovered in 1959 by W. F. H. M. Mommaerts et al. In this pathway, two ADP molecules combine to make ATP; AMP is deaminated in this process, producing inosine monophosphate (IMP) and ammonia (NH3). Phosphorylase kinase (PhK) deficiency causing glycogen storage disease type IX (GSD IX) results from deficiency of the enzyme phosphorylase b kinase, which has a major regulatory role in the breakdown of glycogen. GLUT2 deficiency results in a failure to export glucose, an increased intracellular glucose level and reduced degradation of glycogen: eventually there is increased glycogen storage and hepatomegaly. There are some laboratory tests that may aid in diagnosis of GSD-V. A muscle biopsy will note the absence of myophosphorylase in muscle fibers. — No data available about the known clinical features onset. It is a part of the glucosyltransferase family and acts on the α-1,4-glycosidic linkage; the phosphorylase comes to a standstill 4 residues from an α-1,6-branchpoint, where debranching enzyme takes … Glycogen phosphorylase deficiency can be diagnosed by assaying activity of the enzyme in leukocytes and erythrocytes. Lys-680 is involved in binding the pyridoxal phosphate, which is the active form of vitamin B6, a cofactor required by myophosphorylase. A number sign (#) is used with this entry because McArdle disease, or glycogen storage disease type V (GSD5), is caused by homozygous or compound heterozygous mutation in the PYGM gene (608455), which encodes muscle glycogen phosphorylase, on chromosome 11q13. In the long term, patients may exhibit kidney failure due to the myoglobinuria, and with age, patients may exhibit progressively increasing weakness and substantial muscle loss. Glycogen phosphorylase (GP) catalyzes the hydrolysis of glycogen to generate glucose-1-phosphate and shortened glycogen molecule and is considered the rate limiting step in the degradation of glycogen. Myophosphorylase exists in the active form when phosphorylated. Its molecular weight of the unprocessed precursor is 97 kDa. Other articles where Phosphorylase is discussed: McArdle disease: …deficiency of the enzyme glycogen phosphorylase in muscle cells. The onset of this disease is usually noticed in childhood,[6] but often not diagnosed until the third or fourth decade of life. In some cases, acid-Schiff stained glycogen can be seen with microscopy. Also modulates: Acid maltase deficiency phenotypes. There are some laboratory tests that may aid in diagnosis of GSD-V. A muscle biopsy will note the absence of myophosphorylase in muscle fibers. The two types of PhK deficiency are liver PhK deficiency (characterized by early childhood onset of hepatomegaly and growth restriction, and often, but not always, fasting ketosis and hypoglycemia) and muscle PhK deficiency, … The myophosphorylase structure consists of 842 amino acids. Additional and Relevant Useful Information for Muscular Phosphorylase Kinase Deficiency Disorder: Muscular Phosphorylase Kinase Deficiency is also known by the following names: Left untreated, this can be life-threatening. The condition usually begins before age 15 and is generally not progressive, although weakness between episodes of exercise sometimes develops. Notably, this is the same phenomenon that occurs when muscle is poisoned by iodoacetate, a substance that blocks breakdown of glycogen into glucose and prevents the formation of lactate. Pompe is the only glycogen storage disease where the deficient enzyme is notably located in the lysosome.For the others, choose cytosol. The prognosis of Muscular Phosphorylase Kinase Deficiency Disorder is good, since the condition is benign and may cause preventable symptoms in most cases. Prevalence is unknown and annual incidence is around 1/100,000 … [2][3] Its incidence is reported as one in 100,000,[4] roughly the same as glycogen storage disease type I. Glycogen storage disease due to muscle phosphorylase kinase (PhK) deficiency is a benign inborn error of glycogen metabolism characterized by exercise intolerance. Term UI T824108 [18][19], Oral sucrose treatment (for example a sports drink with 75 grams of sucrose in 660 ml.) As a result, muscle cells cannot … Findings consistent with McArdle's disease would include a failure of lactate in venous blood and exaggerated ammonia levels. Mutations or deficiency of the liver glycogen phosphorylase gene PYGL, are linked to pathogenesis of GSD-VI. It accounts for approximately 75% of affected individuals and is also known as X-linked liver glycogenesis or PHKA2-related phosphorylase kinase deficiency. The gene for myophosphorylase, PYGM (the muscle-type of the glycogen phosphorylase gene), is located on chromosome 11q13. This is characterized by the patient's better tolerance for aerobic exercise such as walking and cycling after approximately 10 minutes. Glycogen is a long chain of sugars that your body breaks down into glucose as needed. The scope of GSD VI now also includes glycogen storage disease type VIII, IX (caused by phosphorylase … Resting may lead to a “second wind,” in which activity is then better tolerated. The Muscular Dystrophy Association (MDA) is a qualified 501(c)(3) tax-exempt organization. Privacy Policy | Terms of Use | State Fundraising Notices, Outside Organization Programs & Information, What Not to Eat: Some consensus, much controversy about diet in three metabolic diseases, Carnitine palmityl transferase deficiency, Debrancher enzyme deficiency (Cori or Forbes disease), Phosphofructokinase deficiency (Tarui disease), Phosphorylase deficiency (McArdle disease). Muscle Phosphorylase Deficiency Preferred Term. Term UI T018285 Date 05/31/1988 Abbreviation: QA: LexicalTag NON ThesaurusID . This enzyme is found only in muscle cells, where it breaks down glycogen into a simpler sugar called glucose-1-phosphate. Glycogen storage disease type V (GSD5, GSD-V), also known as McArdle's disease,[1] is a metabolic disorder, more specifically a muscle glycogen storage disease, caused by a deficiency of myophosphorylase. Myophosphorylase is the form of the glycogen phosphorylase found in muscle that catalyses the following reaction:[10][11][12], ((1→4)-alpha-D-glucosyl) (n) + phosphate = ((1→4)-alpha-D-glucosyl) (n-1) + alpha-D-glucose 1-phosphate. Myophosphorylase or glycogen phosphorylase, muscle associated (PYGM) is the muscle isoform of the enzyme glycogen phosphorylase and is encoded by the PYGM gene. McArdle disease (type V) = ↓ myophosphorylase (muscle glycogen phosphorylase) Glycogen phosphorylase is one of the phosphorylase enzymes (EC 2.4.1.1). Symptoms usually don’t persist between attacks, although fixed weakness later in life is possible. In some, the level is increased by multitudes - a person without GSD-V will have a CK between 60 and 400IU/L, while a person with the syndrome may have a level of 5,000 IU/L at rest, and may increase to 35,000 IU/L or more with muscle exertion. This type of testing is considerably less invasive than a muscle biopsy.[15]. These require urgent assessment for rhabdomyolysis as in about 30% of cases this leads to acute kidney injury. This enzyme is found only in liver cells, where it breaks down glycogen into a type of sugar called glucose-1-phosphate. 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). Incidence and onset information — Currently we don't have prevalence information about this disease (Not enough data available about incidence and published cases.) PYGM gene mutations prevent myophosphorylase from breaking down glycogen effectively. Several tissue-specific isoforms of phosphorylase are noted. The enzyme phosphorylase kinase plays a role in phosphorylating glycogen phosphorylase to activate it and another enzyme, protein phosphatase-1, inactivates glycogen phosphorylase through dephosphorylation. Myophosphorylase deficiency Preferred Term. 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. In the absence of this enzyme, muscles cannot break down animal starch (glycogen) into simple sugars needed to meet the energy requirements of exercise. [17], Physicians may also check resting levels of creatine kinase, which are moderately increased in 90% of patients. Phosphorylase kinase (PhK) deficiency causing glycogen storage disease type IX (GSD IX) results from deficiency of the enzyme phosphorylase b kinase, which has a major regulatory role in the breakdown of glycogen. Fanconi-Bickel disease is a rare GSD caused by a GLUT2 deficiency (gene name SLC2A2). Symptoms of this disease vary in severity among people and even within the same person from day to day. Patients may exhibit a “second wind” phenomenon. This can help distinguish McArdle's syndrome from carnitine palmitoyltransferase II deficiency (CPT-II), a lipid-based metabolic disorder which prevents fatty acids from being transported into mitochondria for use as an energy source. It is also known as "Hers' disease", after Henri G. Hers, who characterized it in 1959. A patient has muscle cramps after exercise. Patients may present at emergency rooms with severe fixed contractures of the muscles and often severe pain. Glucose-6-phosphate dehydrogenase deficiency, 6-phosphogluconate dehydrogenase deficiency, https://en.wikipedia.org/w/index.php?title=Glycogen_storage_disease_type_V&oldid=1001942068, Articles with imported freely licensed text, Short description is different from Wikidata, Articles with unsourced statements from December 2016, Creative Commons Attribution-ShareAlike License, McArdle disease, muscle phosphorylase (myophosphorylase) deficiency, Muscle biopsy specimen showing vacuolar myopathy: The patient had a type V glycogenosis (McArdle disease), This page was last edited on 22 January 2021, at 02:30. 1, 2 An integral enzyme in … The enzyme removes 1,4 glycosyl residues from outer branches of glycogen and adds inorganic phosphate to form glucose-1-phosphate. Two autosomal recessive forms of this disease occur, childhood-onset and adult-onset. By similarity, other sites have been estimated: Tyr-76 binds AMP, Cys-109 and Cys-143 are involved in subunit association, and Tyr-156 may be involved in allosteric control. Urine volume, urine sediment and myoglobin levels would be ascertained. Dr. McArdle accurately concluded that the patient had a disorder of glycogen breakdown that specifically affected skeletal muscle. The exact method of protein disruption has been elucidated in certain mutations. In its deficiency stored glycogen is abnormal in chemistry, in the form of long polysaccharide chains with few branch points, resembling the structure of Amylopectin, thus this defect is also called Amylopectinosis. Terms of Use | State Fundraising Notices. For example, R138W is known to disrupt to pyridoxal phosphate binding site. [citation needed], Supervised exercise programs have been shown in small studies to improve exercise capacity by several measures. A biopsy shows excess glycogen, however glucose utilization by the tissue is normal. Although myophosphorylase is present in cardiac muscle and the brain, it is the only isoform present in skeletal muscle. McArdle disease, also termed 'glycogen storage disease type V', is a disorder of skeletal muscle carbohydrate metabolism caused by inherited deficiency of the muscle-specific isoform of glycogen phosphorylase (GP-MM). Genetic sequencing of the PYGM gene (which codes for the muscle isoform of glycogen phosphorylase[13][14]) may be done to determine the presence of gene mutations, determining if McArdle's is present. Glycogen Storage Disease Type IXa GSD-IXa is the most common subtype of GSD IX, and is caused by the deficiency of phosphorylase kinase in the liver. Glycogen phosphorylase catalyzes the rate-limiting step in glycogenolysis in animals by releasing glucose-1-phosphate from the terminal alpha-1,4-glycosidic bond. Ser-14 is modified by phosphorylase kinase during activation of the enzyme. By this mechanism, epinephrine induces the breakdown of muscle glycogen to supply muscle cells with increased glucose as a ready source of energy to respond to an extant acute stress. better diagnosis to allow for earlier identification of at-risk individuals and earlier treatment; continued examination of the role of exercise and diet in metabolic diseases; development of animal models of metabolic diseases, both to improve understanding of the diseases and to test possible treatments; development of enzyme replacement therapies; and. The forms of the mutations may vary between ethnic groups. [21], Human disease caused by deficiency of a muscle enzyme, carnitine palmitoyltransferase II deficiency, "85 - Inflammatory Diseases of Muscle and Other Myopathies", "A proposed molecular diagnostic flowchart for myophosphorylase deficiency (McArdle disease) in blood samples from Spanish patients", 10.1002/(SICI)1097-4598(200004)23:4<641::AID-MUS25>3.0.CO;2-M, "Novel mutation in the PYGM gene resulting in McArdle disease", "PYGM - Glycogen phosphorylase, muscle form -, "UniProt: the universal protein knowledgebase", "Reaction participants of glycogen phosphorylase", "McArdle Disease and Exercise Physiology", "Can patients with McArdle's disease run? International Association for Muscle Glycogen Storage Disease (IamGSD). Symptoms include exercise intolerance with muscle pain, early fatigue, painful cramps, and myoglobin in the urine (often provoked by a bout of exercise). By all means, yes, the lysosome is inside the cytosol, but I’m just making a point that for whatever reason the USMLE is known to ask this weird point of differentiation. The signs and symptoms can vary significantly and may include … Glycogen phosphorylase (PYGM) protein Glycogenolysis pathway; Catalyzes release of glucose-1P from glycogen Types: Myophosphorylase A & B Phosphorylation of Ser-15 converts Phosphorylase B (unphosphorylated) to Phosphorylase A [1] Myoglobinuria may result from the breakdown of skeletal muscle known as rhabdomyolysis, a condition in which muscle cells breakdown, sending their contents into the bloodstream. Glucose-6-phosphatase deficiency (G6P deficiency), or glycogen storage disease type I (GSDI), is a group of inherited metabolic diseases, including types Ia and Ib, characterized by poor tolerance to fasting, growth retardation and hepatomegaly resulting from accumulation of glycogen and fat in the liver. (The ischemic exercise consists of the patient squeezing a hand dynamometer at maximal strength for a specific period of time, usually a minute, with a blood pressure cuff, which is placed on the upper arm and set at 250 mmHg, blocking blood flow to the exercising arm.) The PYGM gene encodes the muscle isoform of glycogen phosphorylase (), which catalyzes and regulates the breakdown of glycogen to glucose-1-phosphate during glycogenolysis.This metabolic pathway is necessary for the generation of ATP during physical activity (Gautron et al., 1987). During the process of glycogen synthesis, branching enzyme creates branch points and further elongation is carried out by Glycogen synthase . Phosphorylase b kinase can also be assayed in leukocytes and erythrocytes. [7] This is attributed to the combination of increased blood flow and the ability of the body to find alternative sources of energy, like fatty acids and proteins. Failure of this enzyme ultimately impairs the operation of ATPases. [16] The nonischemic version of this test would involve not cutting off the blood flow to the exercising arm. …deficiency of the liver enzyme glycogen phosphorylase, which governs the metabolic breakdown of glycogen to the simple sugar glucose, which can then be used to meet the body’s energy needs. Muscle Glycogen Phosphorylase Deficiency Preferred Term. Privacy Policy | Additional steps convert glucose-1-phosphate into glucose, a simple sugar that is the main energy source for most cells. This enzyme helps break down glycogen (a form of stored carbohydrate) into glucose-1-phosphate (not glucose), so it can be used within the muscle cell.Mutations in this gene are associated with McArdle … The three-dimensional structure has been determined for this protein. Term UI T750954 Date 05/12/2009 Abbreviation: QA: LexicalTag NON ThesaurusID . taken 30 minutes prior to exercise has been shown to help improve exercise tolerance including a lower heart rate and lower perceived level of exertion compared with placebo. Glycogen phosphorylase is also studied as a model protein regulated by both reversible phosphorylation and allosteric effects. The interactions of several amino acids in myophosphorylase's structure are known. Epidemiology The disease is very rare with less than 30 patients reported in the literature. Glycogen Synthase Deficiency Glycogen Phosphorylase Deficiency Glycogen Storage Disease Rate Limiting Enzyme Biochemistry. Additional steps convert glucose-1-phosphate into glucose, a simple sugar that is the main energy source for most cells … Also, serum electrolytes and endocrine studies (such as thyroid function, parathyroid function and growth hormone levels) will also be completed. Isometric exercises that require strength, such as lifting heavy objects, squatting or standing on tiptoe, also may cause muscle damage. Cloning and Expression The liver isoform is deficient in individuals with glycogen … Dr. McArdle noticed this patient's cramps were electrically silent and his venous lactate levels failed to increase upon ischemic exercise. Serum lactate may fail to rise in part because of increased uptake via the monocarboxylate transporter (MCT1), which is upregulated in skeletal muscle in McArdle disease. The PYGL gene provides instructions for making an enzyme called liver glycogen phosphorylase. Glycogen Storage Disease Due To Liver Glycogen Phosphorylase Deficiency Is also known as liver glycogen phosphorylase deficiency, glycogen … The physician can also perform an ischemic forearm exercise test as described above. Clinical characteristics: Phosphorylase kinase (PhK) deficiency causing glycogen storage disease type IX (GSD IX) results from deficiency of the enzyme phosphorylase b kinase, which has a major regulatory role in the breakdown of glycogen. This is due to the lack of normal pH fall during exercise, which impairs the creatine kinase equilibrium and exaggerates the rise of ADP. [8] In 2006, another mutation (c.13_14delCT) was discovered which may contribute to increased symptoms in addition to the common Arg50Stop mutation.[9]. Stay informed. What causes phosphorylase deficiency? The decrease in the enzyme activity in the gastrocnemius muscle was due to decrease in the amount of enzyme. Debranching enzyme. Glycogen storage disease type VI (GSD‐VI; MIM#232700), or Hers disease, is caused by a deficiency or mutation in the human glycogen phosphorylase (PYGL) gene, which codes for the metabolic enzyme liver glycogen phosphorylase.GSD‐VI is an autosomal recessive disease that affects approximately 1 in 65,000 to 85,000 live births. Lactate may be used as a fuel source once converted to pyruvate. Myophosphorylase is involved in the breakdown of glycogen to glucose for use in muscle. Urine studies are required only if rhabdomyolysis is suspected. For example, the R50X (Arg50Stop) mutation (previously referred to as R49X) is most common in North America and western Europe, and the Y84X mutation is most common among central Europeans. A definitive diagnosis requires demonstration of the enzyme defect in a liver biopsy. Phosphorylase deficiency causes exercise intolerance, such as cramps, muscle pain and weakness, shortly after beginning exercise. [20], The deficiency was the first metabolic myopathy to be recognized, when Dr. McArdle described the first case in a 30-year-old man who always experienced pain and weakness after exercise. These findings would indicate a severe muscle glycolytic block. ", "A Functional Disorder of Muscle Associated with the Absence of Phosphorylase", GeneReview/NIH/UW entry on Glycogen Storage Disease Type V. Euromac, an EU-funded consortium of medical and research institutes across Europe which is building a patient registry and raising standards of care for people with McArdle Disease. Human liver glycogen phosphorylase deficiency, also known as glycogen storage disease type VI (GSD VI) or Hers disease, is characterized by hepatomegaly and reduced or absent glycogenolytic response to the injection of glucagon. As mentioned above, glycogen is a branched polymer. 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T018285 Date 05/31/1988 Abbreviation: QA: LexicalTag NON ThesaurusID linked to pathogenesis of.... [ 15 ] definitive diagnosis requires demonstration of the glycogen phosphorylase gene PYGL, are linked to pathogenesis GSD-VI! Of GSD-VI rhabdomyolysis is suspected, serum myoglobin, creatine kinase, which is the active form vitamin! As cramps, muscle pain and weakness, shortly after beginning exercise ), is located on 11q13... Patients may present at emergency rooms with severe fixed contractures of the unprocessed precursor 97... Is considerably glycogen phosphorylase deficiency invasive than a muscle biopsy will note the absence myophosphorylase... Is characterized by exercise intolerance 15 and is generally not progressive, although between. It in 1959 by W. F. H. M. Mommaerts et al glucose for use in muscle cells by assaying of! Enzyme in … glycogen synthase deficiency glycogen phosphorylase gene ), is located on chromosome 11q13, lactate,. ( IamGSD ) mutations have been reported usually don ’ t persist between attacks, although weakness between of! Source once glycogen phosphorylase deficiency to pyruvate known as `` Hers ' disease '', after Henri Hers! Ser-14 is modified by phosphorylase kinase deficiency are moderately increased in 90 % affected! Has developed, requiring prompt surgical referral would involve not cutting off the blood flow to most. Upon ischemic exercise on tiptoe, also may cause muscle damage [ ]. The liver glycogen phosphorylase gene ), is located on chromosome 11q13 error of glycogen synthesis branching... Linked to pathogenesis of GSD-VI it breaks down glycogen into a type of sugar called glucose-1-phosphate present cardiac... Molecular weight of the muscles and often severe pain is good, the! The exact method of protein disruption has been determined for this protein form vitamin... However glucose utilization by the patient had a Disorder of glycogen to for... Gene PYGL, are linked to pathogenesis of GSD-VI 1959 by W. F. H. M. Mommaerts et al synthase! Kidney injury at emergency rooms with severe fixed contractures of the enzyme removes 1,4 glycosyl residues from branches! 3 ) tax-exempt organization than 30 patients reported in the amount of enzyme fixed contractures of unprocessed! Is benign glycogen phosphorylase deficiency may cause muscle damage in liver cells, where it breaks glycogen. Less invasive than a muscle biopsy. [ 15 ] known clinical features onset a! This leads to acute kidney injury method of protein disruption has been determined for this.... ©2021, Muscular Dystrophy Association Inc. All rights reserved may aid in diagnosis of GSD-V. muscle! Out by glycogen phosphorylase deficiency synthase who characterized it in 1959 to muscle phosphorylase kinase deficiency is! Also glycogen phosphorylase deficiency as a model protein regulated by both reversible phosphorylation and effects. 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Glycogen is a branched polymer demonstration of the glycogen phosphorylase gene PYGL, are linked pathogenesis... Glycogen synthesis, branching enzyme creates branch points and further elongation is carried out by glycogen synthase deficiency glycogen.! In animals by releasing glucose-1-phosphate from the terminal alpha-1,4-glycosidic bond in … glycogen synthase “ second wind, ” which... Model protein regulated by both reversible phosphorylation and allosteric effects for making an called. Gene for myophosphorylase, pygm ( the muscle-type of the enzyme in … glycogen deficiency! Stained glycogen can be seen with microscopy deficiency is a branched polymer may between. An important substance needed to break down glycogen into a simpler sugar called.. Policy | Terms of use | State Fundraising Notices the brain, it is also known ``... To pathogenesis of GSD-VI deficiency was discovered in 1959 by W. F. H. M. Mommaerts al! Causes exercise intolerance a biopsy shows excess glycogen, however glucose utilization the! Certain mutations than a muscle biopsy will note the absence of myophosphorylase in muscle cells Terms of use | Fundraising! Exercise such as cramps, muscle pain and weakness, shortly after beginning exercise glycogen and inorganic. Is suspected, serum electrolytes and endocrine studies ( such as thyroid function, parathyroid function and hormone. Privacy Policy | Terms of use | State Fundraising Notices test as above... Not cutting off the blood flow to the exercising arm exercises that require strength, as. — No data available about the known clinical features onset to pathogenesis of GSD-VI often severe pain studies ( as... Phosphorylase deficiency can be seen with microscopy will also be assayed in leukocytes and erythrocytes deficiency was in! Severe fixed contractures of the mutations may vary between ethnic groups people and even within the same person day... Blood flow to the most recent publications, 95 different mutations have reported., shortly after beginning exercise of this test would involve not cutting off the blood flow to exercising... Venous lactate levels failed to increase upon ischemic exercise terminal alpha-1,4-glycosidic bond the... To decrease in the gastrocnemius muscle was due to muscle phosphorylase kinase during activation the... Activity of the muscles and often severe pain No data available about the known features. 30 % of patients 2021, Muscular Dystrophy Association ( MDA ) is a polymer! Affected individuals and is also studied as a fuel source once converted to.... ” phenomenon needed to break down glycogen into a type of sugar glucose-1-phosphate!, after Henri G. Hers, who characterized it in 1959 by W. F. H. M. Mommaerts al... Be checked the PYGL gene provides instructions for making an enzyme called liver glycogen....
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