![]() | This article needs editing to comply with Wikipedia's Manual of Style. In particular, it has problems with not using MEDMOS.(October 2021) |
Phosphofructokinase deficiency | |
---|---|
Other names | Glycogen storage disease type VII or Tarui's disease [1] [2] |
![]() | |
A rendering of the human muscular form of phosphofructokinase. Mutations in the production of this enzyme are the cause of Tarui's disease. [3] The symmetry of the enzyme is a result of its tetrameric structure. | |
Specialty | Endocrinology ![]() |
Symptoms | Muscle pain, exercise intolerance, hemolytic anemia |
Phosphofructokinase deficiency is a rare muscular metabolic disorder, with an autosomal recessive inheritance pattern. It is characterized as a deficiency in the Phosphofructokinase (PFK) enzyme throughout the body, including the skeletal muscles and red blood cells. Phosphofrucotkinase is an enzyme involved in the glycolytic process. The lack of PFK blocks the completion of the glycolytic pathway. Therefore, all products past the block would be deficient, including Adenosine triphosphate (ATP).
It may affect humans as well as other mammals (especially dogs). [4] It was named after the Japanese physician Seiichiro Tarui (b. 1927), who first observed the condition in 1965. [5]
Human PFK deficiency is categorized into four types: classic, late-onset, infantile and hemolytic. These types are differentiated by age at which symptoms are observed and which symptoms present. [6]
Classic phosphofructokinase deficiency is the most common type of this disorder. This type presents with exercise-induced muscle cramps and weakness (sometimes rhabdomyolysis), myoglobinuria, as well as with haemolytic anaemia causing dark urine a few hours later. [7] Hyperuricemia is common, due to the kidneys' inability to process uric acid following damage resulting from processing myoglobin. Nausea and vomiting following strenuous exercise is another common indicator of classic PFK deficiency. Many patients will also display high levels of bilirubin, which can lead to a jaundiced appearance. Symptoms for this type of PFK deficiency usually appear in early childhood.[ citation needed ]
Late-onset PFK deficiency, as the name suggests, is a form of the disease that presents later in life. Common symptoms associated with late-onset phosphofructokinase deficiency are myopathy, weakness and fatigue. Many of the more severe symptoms found in the classic type of this disease are absent in the late-onset form.[ citation needed ]
Phosphofructokinase deficiency also presents in a rare infantile form. Infants with this deficiency often display floppy infant syndrome (hypotonia), arthrogryposis, encephalopathy and cardiomyopathy. The disorder can also manifest itself in the central nervous system, usually in the form of seizures. PFK deficient infants also often have some type of respiratory issue. Survival rate for the infantile form of PFK deficiency is low, and the cause of death is often due to respiratory failure.[ citation needed ]
The defining characteristic of this form of the disorder is hemolytic anemia, in which red blood cells break down prematurely. Muscle weakness and pain are not as common in patients with hemolytic PFK deficiency.[ citation needed ]
Presentation of the canine form of the disease is similar to that of the human form. Most notably, PFK deficient dogs have mild, but persistent, anemia with hemolytic episodes, exercise intolerance, hemoglobinuria, and pale or jaundiced mucous membranes. [8] Muscle weakness and cramping are not uncommon symptoms, but they are not as common as they are in human PFKM deficiency.[ citation needed ]
In order to get Tarui's disease, both parents must be carriers of the genetic defect so that the child is born with the full form of the recessive trait. The best indicator of risk is a family member with PFK deficiency. [9]
Canine phosphofructokinase deficiency is found mostly in English Springer Spaniels and American Cocker Spaniels, but has also been reported in Whippets and Wachtelhunds. [10] [11] Mixed-breed dogs descended from any of these breeds are also at risk to inherit PFK deficiency.[ citation needed ]
Phosphofructokinase is a tetrameric enzyme that consists of three types of subunits: PFKL (liver), PFKM (muscle), and PFKP (platelet). The combination of these subunits varies depending on the tissue in question. [12] In this condition, a deficiency of the M subunit (PFKM) of the phosphofructokinase enzyme impairs the ability of cells such as erythrocytes and rhabdomyocytes (skeletal muscle cells) to use carbohydrates (such as glucose) for energy. Unlike most other glycogen storage diseases, it directly affects glycolysis. [13] The mutation impairs the ability of phosphofructokinase to phosphorylate fructose-6-phosphate prior to its cleavage into glyceraldehyde-3-phosphate which is the rate limiting step in the glycolysis pathway. Inhibition of this step prevents the formation of adenosine triphosphate (ATP) from adenosine diphosphate (ADP), which results in a lack of available energy for muscles during heavy exercise. This results in the muscle cramping and pain that are common symptoms of the disease. [14]
Genetic mutation is the cause of phosphofructokinase deficiency. Several different mutations in the gene that encodes for PFKM have been reported in humans, but the result is production of PFKM subunits with little to no function. [15] As a result, affected individuals display only about 50–65% of total normal phosphofructokinase enzyme function. [16]
PFK deficiency is believed to be the result of a nonsense mutation in the gene that encodes for PFKM. This results in an unstable, truncated protein that lacks normal function. This results in a near complete loss of PFKM activity in the skeletal muscle. Dogs with the mutation display 10–20% of normal PFK activity in their erythrocytes, due to a higher proportion of PFKM in those cells. [17]
Symptoms of phosphofructokinase deficiency can closely resemble those of other metabolic diseases, include deficiencies of phosphoglycerate kinase, phosphoglycerate mutase, lactate dehydrogenase, beta-enolase and aldolase A. [7] Thus, proper diagnosis is important to determine a treatment plan.[ citation needed ]
A diagnosis can be made through a muscle biopsy that shows excess glycogen accumulation. Glycogen deposits in the muscle are a result of the interruption of normal glucose breakdown that regulates the breakdown of glycogen. Blood tests are conducted to measure the activity of phosphofructokinase, which would be lower in a patient with this condition. [19] Patients also commonly display elevated levels of creatine kinase. [7]
Treatment usually entails that the patient refrain from strenuous exercise to prevent muscle pain and cramping. Avoiding carbohydrates is also recommended. [20]
A ketogenic diet also improved the symptoms of an infant with PFK deficiency. The logic behind this treatment is that the low-carb high fat diet forces the body to use fatty acids as a primary energy source instead of glucose. This bypasses the enzymatic defect in glycolysis, lessening the impact of the mutated PFKM enzymes. This has not been widely studied enough to prove if it is a viable treatment, but testing is continuing to explore this option. [21]
Genetic testing to determine whether or not a person is a carrier of the mutated gene is also available.
Mitapivat (brand name Pyrukynd) may improve symptoms by stimulating pyruvate kinase, another enzyme in the glycolytic pathway. [22]
Diagnosis of canine phosphofructokinase deficiency is similar to the blood tests used in diagnosis of humans. Blood tests measuring the total erythrocyte PFK activity are used for definitive diagnosis in most cases. [23] DNA testing for presence of the condition is also available. [24]
Treatment mostly takes the form of supportive care. Owners are advised to keep their dogs out of stressful or exciting situations, avoid high temperature environments and strenuous exercise. It is also important for the owner to be alert for any signs of a hemolytic episode. Dogs carrying the mutated form of the gene should be removed from the breeding population, in order to reduce incidence of the condition.
Kocher–Debré–Semelaigne syndrome (KDSS) is hypothyroidism in infancy or childhood characterised by lower extremity or generalized muscular hypertrophy, myxoedema, short stature, and cognitive impairment.
Glycogen storage disease type V, also known as McArdle's disease, is a metabolic disorder, one of the metabolic myopathies, more specifically a muscle glycogen storage disease, caused by a deficiency of myophosphorylase. Its incidence is reported as one in 100,000, roughly the same as glycogen storage disease type I.
A glycogen storage disease is a metabolic disorder caused by a deficiency of an enzyme or transport protein affecting glycogen synthesis, glycogen breakdown, or glucose breakdown, typically in muscles and/or liver cells.
Maltase is an informal name for a family of enzymes that catalyze the hydrolysis of disaccharide maltose into two simple sugars of glucose. Maltases are found in plants, bacteria, yeast, humans, and other vertebrates.
Phosphofructokinase-1 (PFK-1) is one of the most important regulatory enzymes of glycolysis. It is an allosteric enzyme made of 4 subunits and controlled by many activators and inhibitors. PFK-1 catalyzes the important "committed" step of glycolysis, the conversion of fructose 6-phosphate and ATP to fructose 1,6-bisphosphate and ADP. Glycolysis is the foundation for respiration, both anaerobic and aerobic. Because phosphofructokinase (PFK) catalyzes the ATP-dependent phosphorylation to convert fructose-6-phosphate into fructose 1,6-bisphosphate and ADP, it is one of the key regulatory steps of glycolysis. PFK is able to regulate glycolysis through allosteric inhibition, and in this way, the cell can increase or decrease the rate of glycolysis in response to the cell's energy requirements. For example, a high ratio of ATP to ADP will inhibit PFK and glycolysis. The key difference between the regulation of PFK in eukaryotes and prokaryotes is that in eukaryotes PFK is activated by fructose 2,6-bisphosphate. The purpose of fructose 2,6-bisphosphate is to supersede ATP inhibition, thus allowing eukaryotes to have greater sensitivity to regulation by hormones like glucagon and insulin.
Phosphoglucomutase is an enzyme that transfers a phosphate group on an α-D-glucose monomer from the 1 to the 6 position in the forward direction or the 6 to the 1 position in the reverse direction.
Lysosomal storage diseases are a group of over 70 rare inherited metabolic disorders that result from defects in lysosomal function. Lysosomes are sacs of enzymes within cells that digest large molecules and pass the fragments on to other parts of the cell for recycling. This process requires several critical enzymes. If one of these enzymes is defective due to a mutation, the large molecules accumulate within the cell, eventually killing it.
Glycogen storage disease type II(GSD-II), also called Pompe disease, and formerly known as GSD-IIa or Limb–girdle muscular dystrophy2V, is an autosomal recessive metabolic disorder which damages muscle and nerve cells throughout the body. It is caused by an accumulation of glycogen in the lysosome due to deficiency of the lysosomal acid alpha-glucosidase enzyme (GAA). The inability to breakdown glycogen within the lysosomes of cells leads to progressive muscle weakness throughout the body and affects various body tissues, particularly in the heart, skeletal muscles, liver and the nervous system.
Sandhoff disease is a lysosomal genetic, lipid storage disorder caused by the inherited deficiency to create functional beta-hexosaminidases A and B. These catabolic enzymes are needed to degrade the neuronal membrane components, ganglioside GM2, its derivative GA2, the glycolipid globoside in visceral tissues, and some oligosaccharides. Accumulation of these metabolites leads to a progressive destruction of the central nervous system and eventually to death. The rare autosomal recessive neurodegenerative disorder is clinically almost indistinguishable from Tay–Sachs disease, another genetic disorder that disrupts beta-hexosaminidases A and S. There are three subsets of Sandhoff disease based on when first symptoms appear: classic infantile, juvenile and adult late onset.
Glycogen storage disease type IV (GSD IV), or Andersen's Disease, is a form of glycogen storage disease, which is caused by an inborn error of metabolism. It is the result of a mutation in the GBE1 gene, which causes a defect in the glycogen branching enzyme. Therefore, glycogen is not made properly and abnormal glycogen molecules accumulate in cells; most severely in cardiac and muscle cells. The severity of this disease varies on the amount of enzyme produced. GSD IV is autosomal recessive, which means each parent has a mutant copy of the gene, but show no symptoms of the disease. Having an autosomal recessive inheritance pattern, males and females are equally likely to be affected by Andersen's disease. Classic Andersen's disease typically becomes apparent during the first few months after the patient is born. Approximately 1 in 20,000 to 25,000 newborns have a glycogen storage disease. Andersen's disease affects 1 in 800,000 individuals worldwide, with 3% of all GSDs being type IV. The disease was described and studied first by Dorothy Hansine Andersen.
Fucosidosis is a rare lysosomal storage disorder in which the FUCA1 gene experiences mutations that severely reduce or stop the activity of the alpha-L-fucosidase enzyme. The result is a buildup of complex sugars in parts of the body, which leads to death. Fucosidosis is one of nine identified glycoprotein storage diseases. The gene encoding the alpha-fucosidase, FUCA 1, was found to be located to the short arm of chromosome 1p36 - p34, by Carrit and co-workers, in 1982.
Equine polysaccharide storage myopathy is a hereditary glycogen storage disease of horses that causes exertional rhabdomyolysis. It is currently known to affect the following breeds American Quarter Horses, American Paint Horses, Warmbloods, Cobs, Dales Ponies, Thoroughbreds, Arabians, New Forest ponies, and a large number of Heavy horse breeds. While incurable, PSSM can be managed with appropriate diet and exercise. There are currently 2 subtypes, known as Type 1 PSSM and Type 2 PSSM.
Myophosphorylase or glycogen phosphorylase, muscle associated (PYGM) is the muscle isoform of the enzyme glycogen phosphorylase and is encoded by the PYGM gene. This enzyme helps break down glycogen into glucose-1-phosphate, so it can be used within the muscle cell. Mutations in this gene are associated with McArdle disease, a glycogen storage disease of muscle.
Phosphofructokinase (PFK) is a kinase enzyme that phosphorylates fructose 6-phosphate in glycolysis.
6-phosphofructokinase, muscle type is an enzyme that in humans is encoded by the PFKM gene on chromosome 12. Three phosphofructokinase isozymes exist in humans: muscle, liver and platelet. These isozymes function as subunits of the mammalian tetramer phosphofructokinase, which catalyzes the phosphorylation of fructose-6-phosphate to fructose-1,6-bisphosphate. Tetramer composition varies depending on tissue type. This gene encodes the muscle-type isozyme. Mutations in this gene have been associated with glycogen storage disease type VII, also known as Tarui disease. Alternatively spliced transcript variants have been described.[provided by RefSeq, Nov 2009]
6-phosphofructokinase, liver type (PFKL) is an enzyme that in humans is encoded by the PFKL gene on chromosome 21. This gene encodes the liver (L) isoform of phosphofructokinase-1, an enzyme that catalyzes the conversion of D-fructose 6-phosphate to D-fructose 1,6-bisphosphate, which is a key step in glucose metabolism (glycolysis). This enzyme is a tetramer that may be composed of different subunits encoded by distinct genes in different tissues. Alternative splicing results in multiple transcript variants. [provided by RefSeq, Mar 2014]
Inborn errors of carbohydrate metabolism are inborn error of metabolism that affect the catabolism and anabolism of carbohydrates.
Schindler disease, also known as Kanzaki disease and alpha-N-acetylgalactosaminidase deficiency, is a rare disease found in humans. This lysosomal storage disorder is caused by a deficiency in the enzyme alpha-NAGA (alpha-N-acetylgalactosaminidase), attributable to mutations in the NAGA gene on chromosome 22, which leads to excessive lysosomal accumulation of glycoproteins. A deficiency of the alpha-NAGA enzyme leads to an accumulation of glycosphingolipids throughout the body. This accumulation of sugars gives rise to the clinical features associated with this disorder. Schindler disease is an autosomal recessive disorder, meaning that one must inherit an abnormal allele from both parents in order to have the disease.
Enolase deficiency is a rare genetic disorder of glucose metabolism. Partial deficiencies have been observed in several caucasian families. The deficiency is transmitted through an autosomal dominant inheritance pattern. The gene for enolase 1 has been localized to chromosome 1 in humans. Enolase deficiency, like other glycolytic enzyme deficiences, usually manifests in red blood cells as they rely entirely on anaerobic glycolysis. Enolase deficiency is associated with a spherocytic phenotype and can result in hemolytic anemia, which is responsible for the clinical signs of Enolase deficiency.
Autophagic vacuolar myopathy (AVM) consists of multiple rare genetic disorders with common histological and pathological features on muscle biopsy. The features highlighted are vacuolar membranes of the autophagic vacuoles having sarcolemmal characteristics and an excess of autophagic vacuoles. There are currently five types of AVM identified. The signs and symptoms become more severe over the course of the disease. It begins with an inability to pick up small objects and progresses to difficulty in walking. The age of onset varies from early childhood to late adulthood, affecting people of all ages.
{{cite journal}}
: CS1 maint: unfit URL (link)