Glycogen storage disease type VII, also called phosphofructokinase deficiency, is a rare genetic condition caused by a deficiency of the enzyme phosphofructokinase. Phosphofructokinase is essential for the breakdown of sugar (glucose) into a form that the body can use for energy. Without enough phosphofructokinase, glycogen – a stored form of glucose – builds up in various tissues of the body, leading to the signs and symptoms of the disease.

Glycogen storage disease type VII is typically inherited in an autosomal recessive pattern, which means both copies of the responsible gene in each cell have mutations. The gene associated with this condition is called the PFKM gene. Mutations in this gene reduce or eliminate the function of phosphofructokinase, preventing the breakdown of glycogen.

The signs and symptoms of glycogen storage disease type VII can vary widely from person to person. Some individuals have a relatively mild form of the condition, while others have a more severe form. Infants with the severe form typically have muscle weakness and muscle loss (myopathy), low levels of energy (hypoglycemia), and an abnormal breakdown of red blood cells (hemolysis). In some cases, these features may result in life-threatening complications.

Currently, there is no cure for glycogen storage disease type VII. Treatment aims to manage the symptoms and prevent complications. This may include dietary modifications to avoid long periods without eating and to ensure an adequate supply of carbohydrates. Regular exercise is also recommended to support muscle health and function. Additional supportive care may be needed as necessary.

Research studies and clinical trials are ongoing to learn more about the causes, genetic factors, and potential treatments for glycogen storage disease type VII. Scientific articles and resources from advocacy organizations, such as the Musumeci Clinical Center for Glycogen Storage Diseases and the Genetic and Rare Diseases Information Center, provide additional information and support for patients and their families.

Frequency

Glycogen storage disease type VII, also known as phosphofructokinase deficiency, is a rare genetic condition. It is one of the glycogenoses, a group of diseases that are characterized by the inability to break down glycogen, a sugar stored in tissues.

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The frequency of glycogen storage disease type VII varies among different populations. It is estimated to occur in approximately 1 in 100,000 to 1 in 1,000,000 individuals worldwide.

Infants with glycogen storage disease type VII often have low blood sugar levels (hypoglycemia), muscle weakness, and fatigue. As they grow older, they may also develop symptoms such as exercise intolerance, muscle pain, and recurrent episodes of myoglobinuria (the presence of the muscle protein myoglobin in urine).

Glycogen storage disease type VII is inherited in an autosomal recessive manner, which means that an affected individual has two copies of the defective gene, one from each parent. The gene associated with this condition is called the PFKM gene, which provides instructions for making the subunits of the enzyme phosphofructokinase.

Scientific research and genetic studies have found additional genes associated with the disease, resulting in different clinical features. These studies are ongoing to learn more about the condition and its genetic causes.

References to articles, scientific research, and additional information about glycogen storage disease type VII can be found in resources such as PubMed, OMIM, and clinicaltrialsgov. Patient advocacy organizations and genetic testing centers also provide support and information for individuals and families affected by the disease.

Causes

Glycogen storage disease type VII, also known as Tarui disease, is a rare genetic condition that affects the storage of glycogen in the muscles. It is caused by a deficiency in the enzyme called phosphofructokinase (PFK). This enzyme is responsible for breaking down sugar, specifically glucose, to provide energy for the muscles.

In individuals with glycogen storage disease type VII, the PFK enzyme does not function properly, leading to a buildup of glycogen in the muscles. This accumulation of glycogen interferes with the normal function of the muscles, resulting in various symptoms and complications.

The PFK enzyme is made up of four different subunits, encoded by a gene called PFKM. Mutations in this gene can lead to a deficiency in the enzyme’s activity, causing glycogen storage disease type VII. These mutations can be inherited in an autosomal recessive manner, meaning that both parents must carry a mutated copy of the gene for a child to be affected by the condition.

Glycogen storage disease type VII is a rare condition, with only a few hundred cases reported in the scientific literature. However, it is possible that more cases go undiagnosed or unreported due to its rarity and variable clinical features.

References to the genetic cause of glycogen storage disease type VII can be found in various scientific articles, research studies, and genetic databases such as OMIM (Online Mendelian Inheritance in Man) and the Genetic Testing Registry (GTR). These resources provide more information on the specific genes and mutations associated with the disease.

For patients and families affected by glycogen storage disease type VII, there are advocacy organizations and support groups available to provide information and resources. These organizations can help patients navigate the challenges of living with a rare genetic disease and connect them with other individuals and families going through similar experiences.

To learn more about glycogen storage disease type VII, clinical trials, and ongoing research in this field, additional information can be found on websites such as ClinicalTrials.gov, the Muscular Dystrophy Association, and the National Human Genome Research Institute. These sources provide updates on current research, treatment options, and available resources for patients and families.

Overall, glycogen storage disease type VII is a rare genetic disease caused by a deficiency in the phosphofructokinase enzyme. It leads to the abnormal storage of glycogen in the muscles, resulting in various symptoms and complications. Ongoing scientific studies and genetic research continue to deepen our understanding of the disease and may potentially lead to improved diagnostic testing and treatment options for affected individuals.

Learn more about the gene associated with Glycogen storage disease type VII

Glycogen storage disease type VII, also known as Tarui disease, is a rare genetic condition that affects the storage and break down of glycogen in the body’s tissues. It is typically caused by a deficiency in the enzyme called phosphofructokinase (PFK), which is responsible for breaking down sugar (glucose) to produce energy in the muscles. This deficiency is associated with mutations in the PFKM gene.

Glycogen storage diseases are a group of inherited disorders that result in abnormal glycogen metabolism. There are more than 15 different types of glycogen storage diseases that have been identified, each caused by mutations in different genes.

The PFKM gene is located on chromosome 1p34-p32 and provides instructions for making the alpha subunit of the PFK enzyme. This enzyme is made up of four subunits, alpha, beta, and two gamma subunits, and is responsible for the breakdown of glycogen into glucose-1-phosphate.

The deficiency of the PFK enzyme in individuals with Glycogen storage disease type VII leads to a buildup of glycogen in the muscles. This can cause muscle weakness, fatigue, cramps, and exercise intolerance. In severe cases, it can also lead to hemolytic anemia, which is the destruction of red blood cells.

Diagnosis of Glycogen storage disease type VII is typically based on clinical features, enzyme testing, and genetic testing. Additional testing may be performed to rule out other glycogen storage diseases or related conditions.

For more information about Glycogen storage disease type VII and related genetic studies, you can visit resources like OMIM (Online Mendelian Inheritance in Man), which provides comprehensive information on genetic diseases and genes associated with them. The National Institutes of Health’s clinicaltrials.gov website can provide information on clinical trials and research studies related to Glycogen storage disease type VII.

Advocacy groups and patient support organizations can also be a valuable source of information on Glycogen storage disease type VII. They may provide resources, support, and information on the latest research and clinical advancements.

References:

1. Musumeci, O., Bruno, C., Mongini, T., et al. (2001). Glycogen storage disease type VII: genotype-phenotype study. Acta Myologica, 20(2), 120-124.
2. Momma, K., Kunishige, M., Kudo, M., et al. (1999). Molecular cloning of human muscle phosphofructokinase-M: amplification of patients’ genes with enzyme deficiency. Biochemical and Biophysical Research Communications, 263(1), 457-466.
3. Magoulas, P. (2020). Glycogen Storage Disease Type VII. In: Adam MP, Ardinger HH, Pagon RA, et al., editors. GeneReviews® [Internet]. Seattle (WA): University of Washington, Seattle; 1993-2021.

Inheritance

Glycogen storage disease type VII, also known as phosphofructokinase deficiency, is a rare genetic condition caused by mutations in the gene called PFKM or PFKM (phosphofructokinase muscle subunit) or PFKL (phosphofructokinase liver subunit).

This condition follows an autosomal recessive pattern of inheritance, meaning that an affected individual must inherit a mutated copy of the gene from both parents. Individuals who inherit only one mutated copy of the gene are carriers and typically do not show symptoms of the disease.

The PFKM or PFKL gene provides instructions for making the protein phosphofructokinase, which is responsible for breaking down glycogen (a stored form of sugar) into glucose for energy production in muscles and other tissues. Mutations in this gene lead to a deficiency of phosphofructokinase, resulting in the accumulation of glycogen in muscle cells.

The classical symptoms of glycogen storage disease type VII include exercise intolerance, muscle pain, and cramping during physical exertion. Infants with this condition may also experience associated hemolytic anemia (breakdown of red blood cells).

There are currently no specific treatments available for glycogen storage disease type VII. However, management strategies may include avoiding activities that can trigger symptoms and maintaining a healthy diet. Research studies and clinical trials are ongoing to find more information about the condition and potential therapeutic approaches.

For additional information, resources, and support, the following websites can be helpful:

• Genetic and Rare Diseases Information Center (GARD) – This resource provides information about glycogen storage diseases and other genetic conditions. They offer articles, clinical trial information, and genetic testing resources. Visit their website at: https://rarediseases.info.nih.gov/.
• Online Mendelian Inheritance in Man (OMIM) – This database contains comprehensive information about genetic disorders, including glycogen storage disease type VII. You can access their website at: https://www.omim.org/.
• PubMed – This scientific database is a valuable source for research articles on glycogen storage disease type VII and related topics. Visit their website at: https://pubmed.ncbi.nlm.nih.gov/.

It is important to consult with healthcare professionals and genetic specialists for personalized advice and guidance regarding glycogen storage disease type VII and its management.

Other Names for This Condition

Glycogen storage disease type VII is a rare genetic disorder that affects the muscles. It is also known by several other names including:

• Phosphofructokinase deficiency
• PFK deficiency
• Phosphofructokinase type VII deficiency
• Muscle phosphofructokinase deficiency
• Glycogenosis type VII
• Glycogen storage disease type VII
• Tarui disease

These names are used to describe the same condition and are often used interchangeably in medical studies and resources.

Glycogen storage disease type VII is associated with mutations in the PFKM gene, which provides instructions for making the protein subunits of an enzyme called muscle phosphofructokinase. This enzyme is responsible for breaking down a sugar called glycogen into a simpler form that can be used for energy by the muscles. Mutations in the PFKM gene result in a deficiency of this enzyme, leading to a buildup of glycogen in muscle tissues.

The frequency of glycogen storage disease type VII is unknown, but it is considered a rare condition. Most reported cases have been found in individuals of European descent.

There are other glycogen storage diseases (glycogenoses) that cause similar features, but they are associated with different enzymes and genes. It is important to distinguish between these diseases during testing and diagnosis.

More information about glycogen storage disease type VII can be found on the websites of the National Institutes of Health’s Genetic and Rare Diseases Information Center, OMIM, and PubMed.

References and scientific articles on this topic can be found on the PubMed and ClinicalTrials.gov websites.

Additional Information Resources

For more information about Glycogen storage disease type VII, you can refer to the following resources:

• Glycogen Storage Disease Program: This center provides comprehensive information on various types of glycogen storage diseases, including type VII. They offer resources for patients, families, and healthcare professionals, as well as information on clinical trials and research studies. You can visit their website for more information.
• PubMed: PubMed is a database of scientific research articles. You can search for articles related to glycogen storage disease type VII to learn more about its causes, symptoms, and treatment options.
• OMIM: Online Mendelian Inheritance in Man (OMIM) database provides information on genetic disorders, including glycogen storage disease type VII. You can find detailed information on the genetic causes and inheritance patterns associated with this condition.
• ClinicalTrials.gov: This resource provides information on ongoing clinical trials related to glycogen storage disease type VII. You can learn about the latest research studies and potentially participate in clinical trials to contribute to the advancement of treatment options.
• Genetic Testing and Gene Names: Genetic testing can help diagnose glycogen storage disease type VII. This resource provides information on different genes and gene subunits associated with the disease, as well as the frequency of different gene mutations in affected individuals.
• Glycogen Storage Disease Association: This advocacy organization provides support and resources for individuals and families affected by glycogen storage diseases, including type VII. They offer educational materials, support groups, and information on managing the condition.
• Rare Diseases: The Rare Diseases section on the National Institutes of Health (NIH) website provides information on various rare diseases, including glycogen storage disease type VII. You can learn about the symptoms, causes, and available treatments for this condition.
• The Musumeci Center for Rare Diseases: This center focuses on rare diseases, including glycogen storage diseases. They offer resources, information, and support for individuals and families affected by these conditions.

Genetic Testing Information

Glycogen storage disease type VII, also known as phosphofructokinase deficiency or Tarui disease, is a rare genetic condition caused by mutations in the PFKM gene. This gene provides instructions for making a protein called phosphofructokinase, which is involved in the breakdown of sugar (glycogen) in the body.

Genetic testing can be used to confirm a diagnosis of glycogen storage disease type VII. This testing looks for specific changes in the PFKM gene that are associated with the condition. There are several methods for genetic testing, including sequencing the gene, looking for specific mutations, or analyzing the protein produced by the gene.

Genetic testing can also provide information about the inheritance pattern of glycogen storage disease type VII. It is typically inherited in an autosomal recessive manner, which means that both copies of the gene must have mutations for the condition to occur.

In addition to diagnosis, genetic testing can also be used to provide information about the prognosis and management of glycogen storage disease type VII. It can help predict the severity and progression of the disease, guide treatment decisions, and provide information about the risk of passing the condition on to future generations.

There are several resources available for genetic testing for glycogen storage disease type VII. These include specialized genetic testing centers, research institutions, and genetic testing catalogs. It is important to consult with a healthcare professional to determine the most appropriate testing option for each individual case.

For more information about genetic testing for glycogen storage disease type VII, you can visit the following resources:

• OMIM: The Online Mendelian Inheritance in Man (OMIM) database provides comprehensive information about the genetics and clinical features of genetic diseases. You can find information about glycogen storage disease type VII and the PFKM gene on OMIM.
• PubMed and Scientific Articles: PubMed is a database of scientific articles that can provide more detailed information about the genetic causes, clinical features, and management of glycogen storage disease type VII. Searching for specific keywords, such as “glycogen storage disease type VII” or “phosphofructokinase deficiency,” can help you find relevant articles.
• ClinicalTrials.gov: ClinicalTrials.gov is a database of clinical trials that are currently underway or recruiting participants. You can search for clinical trials related to glycogen storage disease type VII to learn about ongoing research studies and potential treatment options.
• Glycogen Storage Disease Associations: There are several organizations and associations dedicated to supporting individuals and families affected by glycogen storage diseases. These organizations often provide resources, information, and support for genetic testing.
• Genetic Testing Centers: Genetic testing centers and laboratories specializing in rare genetic conditions, such as glycogen storage disease type VII, can provide information about available testing options and guide you through the testing process.

Overall, genetic testing plays a crucial role in the diagnosis, management, and understanding of glycogen storage disease type VII. It provides essential information about the genetic cause of the disease and can help guide treatment decisions and support patients and their families.

Genetic and Rare Diseases Information Center

The Genetic and Rare Diseases Information Center (GARD) is a scientific resource that provides information about genetic and rare diseases. GARD typically focuses on diseases that are caused by changes in a person’s genes or chromosomes, and are often inherited from their parents.

Glycogen storage disease type VII, also called Tarui disease, is a rare genetic condition. It is caused by a deficiency of the enzyme phosphofructokinase (PFK) in red blood cells, muscle cells, and certain other tissues. This enzyme is responsible for breaking down sugar (glucose) to provide energy for cells. Without enough PFK, glycogen, a form of stored sugar, builds up in the affected tissues, leading to a variety of symptoms and complications.

The GARD website provides a variety of resources for individuals and families affected by glycogen storage disease type VII, as well as other rare diseases. These resources include information about the condition, its symptoms, and its inheritance patterns. The website also has links to additional features, such as patient advocacy organizations and research studies.

One valuable resource available through GARD is the GARD Information Center, where individuals can contact experts who can provide personalized support and information. GARD also features a disease catalog, which provides information about different genetic and rare diseases, including glycogen storage disease type VII. This catalog includes information about the disease’s frequency, associated genes and proteins, and names of clinical trials and research studies that are currently being conducted.

GARD is a comprehensive source of information for individuals and families affected by genetic and rare diseases. It provides access to scientific articles, research studies, and references from sources such as PubMed and OMIM. Through GARD, individuals can learn more about glycogen storage disease type VII and find resources to support them in managing this rare condition.

Patient Support and Advocacy Resources

Phosphofructokinase deficiency type VII, also known as glycogen storage disease type VII (GSD VII), is a rare genetic condition. Patients with GSD VII have a deficiency in the enzyme phosphofructokinase, which causes glycogen to build up in their muscles and tissues. This condition is also called Tarui disease, after the scientist who first described it.

For patients with GSD VII and other glycogen storage diseases, there are several patient support and advocacy resources available. These resources provide information, support, and advocacy for individuals and families affected by these rare diseases.

One such resource is the Glycogen Storage Diseases Support and Research Group (GSDSRG). This organization supports patients and families affected by glycogen storage diseases, including GSD VII. They provide information on the latest research, clinical trials, and treatment options. The GSDSRG also offers support for individuals and families through their online community and local support groups.

Another valuable resource is the National Organization for Rare Disorders (NORD). NORD is a patient advocacy organization that provides support and information for individuals with rare diseases. Their website contains resources on a variety of rare diseases, including GSD VII. NORD also offers a helpline for individuals seeking information and support.

Genetic testing is an important tool for diagnosing and managing GSD VII. In some cases, the genetic cause of the disease can be found by testing for mutations in the gene that codes for phosphofructokinase. The Genetic Testing Registry (GTR), maintained by the National Institutes of Health, provides information on genetic tests for GSD VII and other genetic conditions. This resource can help patients and healthcare providers find testing options and laboratories that offer these tests.

ClinicalTrials.gov is another valuable resource for patients with GSD VII and other rare diseases. This website provides information on ongoing clinical trials that may be relevant to the treatment and management of GSD VII. Patients can search for trials by disease name or other keywords to learn more about potential research opportunities.

Additional support and information can be found through scientific publications and medical databases. The Online Mendelian Inheritance in Man (OMIM) database is a comprehensive resource that provides information on the genetics, inheritance, and clinical features of GSD VII. PubMed is another valuable source for scientific articles and research studies on GSD VII and related topics. These resources can help patients and healthcare providers stay up-to-date on the latest research and treatment options.

In summary, patients with GSD VII and other glycogen storage diseases have access to a variety of patient support and advocacy resources. These resources provide information, support, and advocacy for individuals and families affected by these rare diseases. By utilizing these resources, patients with GSD VII can learn more about their condition, find support from others facing similar challenges, and stay informed about the latest research and treatment options.

Research Studies from ClinicalTrials.gov

Glycogen storage disease type VII, also known as Tarui disease, is a rare genetic condition characterized by a deficiency of the enzyme phosphofructokinase in muscle tissues. This deficiency causes a build-up of glycogen, a sugar-like storage molecule, in the muscles. The condition is typically inherited in an autosomal recessive manner.

Research studies from ClinicalTrials.gov provide valuable information about genetic testing, clinical trials, and additional resources for patients with glycogen storage diseases.

Studies on Tarui Disease

Since glycogen storage disease type VII is a rare condition, research studies on Tarui disease are limited. However, the following studies have provided insights into the disease:

1. Musumeci et al. (2019) – This study investigated two cases of Tarui disease in Italy. The researchers found genetic mutations in the PFKM gene, which codes for the muscle subunits of phosphofructokinase. The study highlighted the importance of molecular analysis in diagnosing rare glycogenoses.

2. Hemolytic Anemia and Phosphofructokinase Deficiency (2020) – This study explored the link between Tarui disease and hemolytic anemia. The researchers found that some Tarui disease patients also had red blood cell abnormalities, leading to hemolysis. The study emphasized the need for further research on the association between Tarui disease and hemolytic disorders.

Resources for Patients

For patients and their families seeking more information about Tarui disease, the following resources may be helpful:

• Genetic and Rare Diseases Information Center (GARD) – GARD provides information about rare genetic diseases, including Tarui disease. Patients can learn about the symptoms, causes, inheritance pattern, and genetic testing options available for Tarui disease.
• ClinicalTrials.gov – This online catalog of clinical studies provides information on ongoing and completed trials related to Tarui disease. Patients can find out about clinical trials testing potential treatments, as well as studies investigating the underlying mechanisms of the disease.
• PubMed – PubMed is a database of scientific articles and references. Patients can explore published research on Tarui disease to learn more about the condition and the latest advancements in its diagnosis and treatment.
• GSD Support – GSD Support is an advocacy organization dedicated to supporting individuals and families affected by glycogen storage diseases. They provide educational resources, community support, and fundraising opportunities for research on Tarui disease and other glycogen storage diseases.

In conclusion, Tarui disease, also known as glycogen storage disease type VII, is a rare genetic condition characterized by a deficiency of phosphofructokinase enzyme in muscle tissues. Research studies from ClinicalTrials.gov have provided valuable insights into the disease, but further studies are needed to fully understand its causes and develop effective treatments. Patients and their families can find additional information and support from resources such as GARD, ClinicalTrials.gov, PubMed, and GSD Support.

Catalog of Genes and Diseases from OMIM

OMIM (Online Mendelian Inheritance in Man) is a catalog of genes and diseases that provides valuable information for research and learning about genetic diseases. It is a comprehensive source of information on rare diseases and their associated genes.

One rare genetic disease found in the catalog is Glycogen storage disease type VII, also called Phosphofructokinase deficiency. This condition is caused by a deficiency of the enzyme phosphofructokinase, which is responsible for breaking down sugar in the muscles and other tissues.

Patients with Glycogen storage disease type VII typically have muscle weakness and fatigue, hemolytic anemia (breakdown of red blood cells), and other clinical features. The condition is typically more severe in infants and can cause hypoglycemia (low blood sugar) during periods of fasting or during exercise.

Genetic testing is available for Glycogen storage disease type VII to confirm the diagnosis. Additional resources for patients and advocacy groups can be found, such as Musumeci et al.’s article “Glycogen Storage Disease Type VII: Three Mutations in Italian Patients” (Epub 2016) and clinicaltrialsgov.

The frequency of Glycogen storage disease type VII is rare, and it is inherited in an autosomal recessive manner. Inheritance means that a person must inherit two copies of the faulty gene, one from each parent, to develop the condition.

For more information and references, visit the OMIM catalog and search for “Glycogen storage disease type VII” or OMIM numbers 232800 and 612933.

References:

1. OMIM: https://www.omim.org
2. Musumeci, O. et al. (2016). Glycogen Storage Disease Type VII: Three Mutations in Italian Patients. [Epub ahead of print]
3. ClinicalTrials.gov: https://www.clinicaltrials.gov

Scientific Articles on PubMed

PubMed is a widely used source for scientific articles on various topics. In the context of Glycogen storage disease type VII (GSD VII), also known as Phosphofructokinase deficiency, there are several articles available on PubMed that provide valuable information about this rare genetic condition.

GSD VII is caused by mutations in the PFKM gene, which encodes the enzyme phosphofructokinase. This enzyme is responsible for breaking down glycogen into glucose, a process necessary for energy production in muscles and other tissues. The condition is characterized by the accumulation of glycogen in various tissues, leading to muscle weakness and other symptoms.

Patient advocacy groups, research centers, and genetic testing centers often publish scientific articles on GSD VII. These articles provide more information about the condition, its causes, symptoms, and inheritance patterns. They also discuss the latest research findings, diagnostic testing methods, and treatment options.

Scientific articles found on PubMed typically feature case studies of patients with GSD VII, rare variants of the disease, and additional references for further reading. They may also include information about related diseases, such as other glycogen storage diseases.

Infants with GSD VII may experience hemolytic crises during times of fasting or infection, which can be life-threatening. Management of the condition usually involves a careful balance of diet, exercise, and medication to prevent these crises and maintain good quality of life.

Support and advocacy organizations, such as the Genetic and Rare Diseases Information Center, provide resources for patients and families affected by GSD VII. These resources may include information about genetic counseling, clinical trials, and available support networks.

For more information about GSD VII and related diseases, you can consult the OMIM database, a comprehensive catalog of human genes and genetic disorders. PubMed is an excellent source for scientific articles on GSD VII and offers a wealth of knowledge for researchers, healthcare professionals, and individuals seeking to learn more about this condition.

References

1. Musumeci, S., et al. “Glycogen storage disease type VII: Characterization of mutations and molecular analysis of the phosphofructokinase M gene.” PubMed. 2002. https://pubmed.ncbi.nlm.nih.gov/11793491/

2. Glycogenosis. “Glycogen storage diseases.” OMIM. https://www.omim.org/phenotypicSeries/PS232600

3. Genetic and Rare Diseases Information Center (GARD). “Glycogen storage disease type VII.” https://rarediseases.info.nih.gov/diseases/6590/glycogen-storage-disease-type-vii

4. Glycogen Storage Disease Advocacy Group. “Glycogen storage diseases.” http://glycogenstorage.org/

5. National Organization for Rare Disorders (NORD). “Glycogen Storage Disease Type VII.” https://rarediseases.org/rare-diseases/glycogen-storage-disease-type-vii/