Glycogen storage disease type VII
Glycogen storage disease type VII | |
ICD-10 | E74.0 |
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ICD-9 | 271.0 |
OMIM | 232800 |
DiseasesDB | 5314 |
MeSH | D006014 |
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief:
Synonyms and keywords:
Overview
Historical Perspective
The historical perspective of the glycogen-storage disease type VII is as follows:[1][2]
- In 1965, Tarui first described the phosphofructokinase (PFK) deficiency in 3 siblings with easy fatigability and exercise intolerance.
- The skeletal muscles of these patients had increased muscle glycogen content and high levels of hexose monophosphates.
- In 1967, Layer et al suggested autosomal recessive inheritence of the disease by detecting the disease in a 18 year old male
- Also in 1967, Satoyoshi and Kowa postulated the role of a inhibitor in the development of disease
- Oral ingestion of fructose helped relieve the disease symptoms.
- Assays for muscle PFK revealed almost undetectable activity, and erythrocyte PFK had about 50% normal activity.
- Tarui disease or glycogen-storage disease type VII has since been described in approximately 100 patients worldwide.
Classification
There is no established system for the classification of [disease name].
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[Disease name] may be classified according to [classification method] into [number] subtypes/groups: [group1], [group2], [group3], and [group4].
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[Disease name] may be classified into [large number > 6] subtypes based on [classification method 1], [classification method 2], and [classification method 3]. [Disease name] may be classified into several subtypes based on [classification method 1], [classification method 2], and [classification method 3].
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Based on the duration of symptoms, [disease name] may be classified as either acute or chronic.
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If the staging system involves specific and characteristic findings and features: According to the [staging system + reference], there are [number] stages of [malignancy name] based on the [finding1], [finding2], and [finding3]. Each stage is assigned a [letter/number1] and a [letter/number2] that designate the [feature1] and [feature2].
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The staging of [malignancy name] is based on the [staging system].
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There is no established system for the staging of [malignancy name].
Pathophysiology
- Mutations in the PFKM gene cause Glycogen storage disease type VII.
- PFKM gene signals to make the PFKM subunit of an enzyme called phosphofructokinase, which plays a key role in the metabolism of the glycogen.
- The phosphofructokinase enzyme is made up of four subunits and is found in a variety of tissues.
- Different tissues have different combinations of these four subunits of phosphofructokinase enzyme.
- In skeletal muscles where the main source of energy is stored glycogen, the phosphofructokinase enzyme is solely composed of the PFKM subunits.
- To maintain normal blood sugar levels between meals or during exercise, glycogen is metabolized rapidly into the when energy is needed.
- Phosphofructokinase is involved in the above-mentioned chain of events that metabolizes glycogen to provide energy to muscle cells.
- The mutations of the PFKM gene results in non-functional or dysfunctional PFKM subunits.
- As a result, no functional phosphofructokinase is formed in skeletal muscles, and glycogen cannot be metabolized completely resulting in the accumulation of the partially metabolized glycogen in the skeletal muscle cells.
- If these skeletal muscles are put to a moderate strain such as exercise, cramping ensues as these muscles do not have access to glycogen as an energy source.
- In other tissues, other subunits that make up the phosphofructokinase enzyme likely compensate for the lack of PFKM subunits, and the enzyme is able to retain some function, this compensation may help explain why other tissues are not affected by PFKM gene mutations.
Genetics
- Glycogen storage disease type VII is inherited in an autosomal recessive pattern, which means both copies of the gene in each cell have mutations.
- Recessive genetic disorders occur when an individual inherits the same abnormal gene for the same trait from each parent.
- The parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene, but they typically do not show signs and symptoms of the condition.
- If an individual receives one normal gene and one gene for the disease, the person will be a carrier for the disease, but usually will not show symptoms.
- The risk for two carrier parents to both pass the defective gene and, therefore, have an affected child is 25% with each pregnancy.
- The risk to have a child who is a carrier like the parents is 50% with each pregnancy.
- The chance for a child to receive normal genes from both parents and be genetically normal for that particular trait is 25%.
- Consanguineous marriages have a higher chance than unrelated parents to both carry the same abnormal gene, which increases the risk to have children with a recessive genetic disorder.
Causes
- Glycogen storage disease type VII is inherited as an autosomal recessive genetic disorder.
- GSD type VII is caused by mutation of phosphofructokinase gene in the muscle that results in a deficiency of the phosphofructokinase enzyme which converts fructose-6-phosphate to fructose-1,6-diphosphate.
- This is the rate-limiting step in the metabolism of the glucose into available energy, if the phosphofructokinase is deficient, energy is not available to muscles during heavy exercise and hence pain and cramps occur in the muscle.
Differentiating ((Page name)) from Other Diseases
Epidemiology and Demographics
- The epidemiology and demographics of the Glycogen storage disease type VII are as follows:[9]
- Glycogen storage disease type VII is thought to be a rare condition; more than 100 cases have been described in the scientific literature.
- The incidence of Glycogen storage disease type VII is 2.3 children per 100,000 births per year.
- Glycogen storage disease type VII commonly affects children, all patients of reported cases died by age 4 years.
- Glycogen storage disease type VII usually affects individuals of the individuals of Japanese and Ashkenazi Jewish descent.
- Glycogen storage disease type VII affects men and women equally.
Risk Factors
There are no established risk factors for [disease name].
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The most potent risk factor in the development of [disease name] is [risk factor 1]. Other risk factors include [risk factor 2], [risk factor 3], and [risk factor 4].
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Common risk factors in the development of [disease name] include [risk factor 1], [risk factor 2], [risk factor 3], and [risk factor 4].
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Common risk factors in the development of [disease name] may be occupational, environmental, genetic, and viral.
Screening
There is insufficient evidence to recommend routine screening for [disease/malignancy].
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According to the [guideline name], screening for [disease name] is not recommended.
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According to the [guideline name], screening for [disease name] by [test 1] is recommended every [duration] among patients with [condition 1], [condition 2], and [condition 3].
Natural History, Complications, and Prognosis
If left untreated, [#]% of patients with [disease name] may progress to develop [manifestation 1], [manifestation 2], and [manifestation 3].
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Common complications of [disease name] include [complication 1], [complication 2], and [complication 3].
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Prognosis is generally excellent/good/poor, and the 1/5/10-year mortality/survival rate of patients with [disease name] is approximately [#]%.
Diagnosis
Diagnostic Criteria
The diagnosis of [disease name] is made when at least [number] of the following [number] diagnostic criteria are met: [criterion 1], [criterion 2], [criterion 3], and [criterion 4].
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The diagnosis of [disease name] is based on the [criteria name] criteria, which include [criterion 1], [criterion 2], and [criterion 3].
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The diagnosis of [disease name] is based on the [definition name] definition, which includes [criterion 1], [criterion 2], and [criterion 3].
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There are no established criteria for the diagnosis of [disease name].
History and Symptoms
The majority of patients with [disease name] are asymptomatic.
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The hallmark of [disease name] is [finding]. A positive history of [finding 1] and [finding 2] is suggestive of [disease name]. The most common symptoms of [disease name] include [symptom 1], [symptom 2], and [symptom 3]. Common symptoms of [disease] include [symptom 1], [symptom 2], and [symptom 3]. Less common symptoms of [disease name] include [symptom 1], [symptom 2], and [symptom 3].
Physical Examination
Patients with [disease name] usually appear [general appearance]. Physical examination of patients with [disease name] is usually remarkable for [finding 1], [finding 2], and [finding 3].
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Common physical examination findings of [disease name] include [finding 1], [finding 2], and [finding 3].
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The presence of [finding(s)] on physical examination is diagnostic of [disease name].
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The presence of [finding(s)] on physical examination is highly suggestive of [disease name].
Laboratory Findings
An elevated/reduced concentration of serum/blood/urinary/CSF/other [lab test] is diagnostic of [disease name].
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Laboratory findings consistent with the diagnosis of [disease name] include [abnormal test 1], [abnormal test 2], and [abnormal test 3].
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[Test] is usually normal for patients with [disease name].
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Some patients with [disease name] may have elevated/reduced concentration of [test], which is usually suggestive of [progression/complication].
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There are no diagnostic laboratory findings associated with [disease name].
Electrocardiogram
There are no ECG findings associated with [disease name].
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An ECG may be helpful in the diagnosis of [disease name]. Findings on an ECG suggestive of/diagnostic of [disease name] include [finding 1], [finding 2], and [finding 3].
X-ray
There are no x-ray findings associated with [disease name].
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An x-ray may be helpful in the diagnosis of [disease name]. Findings on an x-ray suggestive of/diagnostic of [disease name] include [finding 1], [finding 2], and [finding 3].
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There are no x-ray findings associated with [disease name]. However, an x-ray may be helpful in the diagnosis of complications of [disease name], which include [complication 1], [complication 2], and [complication 3].
Echocardiography or Ultrasound
There are no echocardiography/ultrasound findings associated with [disease name].
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Echocardiography/ultrasound may be helpful in the diagnosis of [disease name]. Findings on an echocardiography/ultrasound suggestive of/diagnostic of [disease name] include [finding 1], [finding 2], and [finding 3].
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There are no echocardiography/ultrasound findings associated with [disease name]. However, an echocardiography/ultrasound may be helpful in the diagnosis of complications of [disease name], which include [complication 1], [complication 2], and [complication 3].
CT scan
There are no CT scan findings associated with [disease name].
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[Location] CT scan may be helpful in the diagnosis of [disease name]. Findings on CT scan suggestive of/diagnostic of [disease name] include [finding 1], [finding 2], and [finding 3].
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There are no CT scan findings associated with [disease name]. However, a CT scan may be helpful in the diagnosis of complications of [disease name], which include [complication 1], [complication 2], and [complication 3].
MRI
There are no MRI findings associated with [disease name].
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[Location] MRI may be helpful in the diagnosis of [disease name]. Findings on MRI suggestive of/diagnostic of [disease name] include [finding 1], [finding 2], and [finding 3].
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There are no MRI findings associated with [disease name]. However, a MRI may be helpful in the diagnosis of complications of [disease name], which include [complication 1], [complication 2], and [complication 3].
Other Imaging Findings
There are no other imaging findings associated with [disease name].
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[Imaging modality] may be helpful in the diagnosis of [disease name]. Findings on an [imaging modality] suggestive of/diagnostic of [disease name] include [finding 1], [finding 2], and [finding 3].
Other Diagnostic Studies
There are no other diagnostic studies associated with [disease name].
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[Diagnostic study] may be helpful in the diagnosis of [disease name]. Findings suggestive of/diagnostic of [disease name] include [finding 1], [finding 2], and [finding 3].
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Other diagnostic studies for [disease name] include [diagnostic study 1], which demonstrates [finding 1], [finding 2], and [finding 3], and [diagnostic study 2], which demonstrates [finding 1], [finding 2], and [finding 3].
Treatment
Medical Therapy
There is no treatment for [disease name]; the mainstay of therapy is supportive care.
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Supportive therapy for [disease name] includes [therapy 1], [therapy 2], and [therapy 3].
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The majority of cases of [disease name] are self-limited and require only supportive care.
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[Disease name] is a medical emergency and requires prompt treatment.
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The mainstay of treatment for [disease name] is [therapy].
OR The optimal therapy for [malignancy name] depends on the stage at diagnosis.
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[Therapy] is recommended for all patients who develop [disease name].
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Pharmacologic medical therapy is recommended among patients with [disease subclass 1], [disease subclass 2], and [disease subclass 3].
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Pharmacologic medical therapies for [disease name] include (either) [therapy 1], [therapy 2], and/or [therapy 3].
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Empiric therapy for [disease name] depends on [disease factor 1] and [disease factor 2].
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Patients with [disease subclass 1] are treated with [therapy 1], whereas patients with [disease subclass 2] are treated with [therapy 2].
Surgery
Surgical intervention is not recommended for the management of [disease name].
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Surgery is not the first-line treatment option for patients with [disease name]. Surgery is usually reserved for patients with either [indication 1], [indication 2], and [indication 3]
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The mainstay of treatment for [disease name] is medical therapy. Surgery is usually reserved for patients with either [indication 1], [indication 2], and/or [indication 3].
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The feasibility of surgery depends on the stage of [malignancy] at diagnosis.
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Surgery is the mainstay of treatment for [disease or malignancy].
Primary Prevention
There are no established measures for the primary prevention of [disease name].
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There are no available vaccines against [disease name].
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Effective measures for the primary prevention of [disease name] include [measure1], [measure2], and [measure3].
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[Vaccine name] vaccine is recommended for [patient population] to prevent [disease name]. Other primary prevention strategies include [strategy 1], [strategy 2], and [strategy 3].
Secondary Prevention
There are no established measures for the secondary prevention of [disease name].
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Effective measures for the secondary prevention of [disease name] include [strategy 1], [strategy 2], and [strategy 3].
References
- ↑ TARUI S, OKUNO G, IKURA Y, TANAKA T, SUDA M, NISHIKAWA M (1965). "PHOSPHOFRUCTOKINASE DEFICIENCY IN SKELETAL MUSCLE. A NEW TYPE OF GLYCOGENOSIS". Biochem. Biophys. Res. Commun. 19: 517–23. PMID 14339001.
- ↑ Toscano A, Musumeci O (2007). "Tarui disease and distal glycogenoses: clinical and genetic update". Acta Myol. 26 (2): 105–7. PMC 2949577. PMID 18421897.
- ↑
- ↑ The Association for Glycogen Storage Disease > Type I Glycogen Storage Disease Type I GSD This page was created in October 2006.
- ↑
- ↑ http://mcardlesdisease.org/
- ↑ eMedicine Specialties > Pediatrics: Genetics and Metabolic Disease > Metabolic Diseases > Glycogen-Storage Disease Type VI Author: Lynne Ierardi-Curto, MD, PhD. Updated: Aug 4, 2008
- ↑ 8.0 8.1 http://neuromuscular.wustl.edu/msys/glycogen.html#enolase
- ↑ Haller RG, Vissing J (2004). "No spontaneous second wind in muscle phosphofructokinase deficiency". Neurology. 62 (1): 82–6. PMID 14718702.