Glycogen storage disease type IX, also known as glycogenosis type IX, is a rare genetic disorder that affects the way glycogen, a form of stored glucose, is produced and broken down in the body. It is caused by mutations in the genes associated with the production of enzymes called phosphorylases, specifically the PHKA2, PHKB, and PHKG2 genes. This condition is inherited in an X-linked manner, meaning it mainly affects males.
Patients with glycogen storage disease type IX may experience symptoms such as hepatomegaly (enlarged liver), delayed growth, low blood sugar, fatigue, and muscle weakness. These symptoms typically present during childhood and can be worsened by exercise or fasting. The exact frequency of this condition is unknown, but it is considered to be a rare disorder.
To diagnose glycogen storage disease type IX, genetic testing can be performed to identify mutations in the PHKA2, PHKB, and PHKG2 genes. Additional testing, such as muscle biopsy and blood glucose monitoring, may also be done to support the diagnosis. More information on the clinical characteristics and inheritance of glycogen storage disease type IX can be found in resources such as OMIM, PubMed, and scientific articles.
Currently, there is no cure for glycogen storage disease type IX. Treatment mainly focuses on managing symptoms and preventing complications. This may involve dietary modifications, such as consuming frequent meals with carbohydrates, and avoiding prolonged fasting or intense exercise. Regular monitoring and follow-up with healthcare professionals familiar with the condition is important to provide necessary support and manage the disease effectively.
Frequency
Glycogen storage disease type IX (GSD IX) is a rare genetic condition caused by a deficiency in the enzyme phosphorylase kinase (PHK). This enzyme is responsible for breaking down glycogen, a stored form of glucose, into usable energy. GSD IX is also known as glycogenosis type IX.
The frequency of GSD IX is not well documented, but it is estimated to affect approximately 1 in 100,000 individuals worldwide. The condition is more common in certain populations, such as those of Ashkenazi Jewish descent, where the frequency may be higher.
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GSD IX is an X-linked disorder, meaning it primarily affects males. However, females can also be carriers of the condition. The exact frequency of GSD IX in females is not known, but they may experience mild symptoms or be completely asymptomatic.
Most cases of GSD IX are diagnosed in childhood, typically after an episode of myoglobinuria (the presence of myoglobin in urine) following exercise or other strenuous activity. The specific symptoms and severity can vary between patients, but common signs include muscle weakness, muscle cramps, exercise intolerance, and hepatomegaly (enlarged liver).
Genetic testing is typically used to confirm a diagnosis of GSD IX. Mutations in the PHKA2, PHKB, and PHKG2 genes have been associated with the condition. These genes provide instructions for making different components of the PHK enzyme. The severity and specific symptoms of GSD IX can vary depending on the specific gene that is affected.
Delayed diagnosis of GSD IX can have significant implications for patient care and management. Prompt identification and treatment are important for preventing complications and providing appropriate support. For more information about genetic testing and resources for GSD IX, additional references can be found on OMIM and PubMed.
In conclusion, GSD IX is a rare genetic condition that affects the function of an enzyme involved in glycogen metabolism. It is associated with a frequency of approximately 1 in 100,000 individuals worldwide. Early diagnosis and management are crucial for optimizing patient outcomes. Ongoing research and clinical trials are providing additional information about the causes, clinical manifestations, and treatment options for GSD IX.
Causes
Glycogen storage disease type IX, also known as PHKB deficiency, is a rare genetic condition that affects the function of the enzyme phosphorylase kinase. This enzyme is responsible for breaking down glycogen into glucose, a key source of energy for the body.
The condition is typically caused by mutations in the PHKB gene, which is located on the X chromosome. These mutations can disrupt the production or function of phosphorylase kinase, leading to a buildup of glycogen in various tissues, including the liver and muscles.
The exact frequency of glycogen storage disease type IX is unknown, but it is considered a rare disease. It is estimated to affect fewer than 1 in 100,000 individuals.
The diagnosis of glycogen storage disease type IX is usually made in childhood or early adulthood. Symptoms can vary widely and may include hepatomegaly (enlarged liver), muscle weakness, exercise intolerance, and myoglobinuria (the presence of myoglobin in the urine).
Genetic testing can confirm the diagnosis and identify the specific mutation in the PHKB gene. It can also help determine the inheritance pattern of the condition, as glycogen storage disease type IX can be inherited in an X-linked recessive manner.
More research is needed to fully understand the underlying causes of glycogen storage disease type IX and to develop targeted treatments. Ongoing studies and clinical trials can provide valuable information about the disease and potential therapeutic options.
For more information about glycogen storage disease type IX, its causes, and available resources, you can refer to the following references:
- OMIM (Online Mendelian Inheritance in Man) catalog – a comprehensive database of human genes and genetic disorders.
- PubMed – a database of scientific articles.
- ClinicalTrials.gov – a registry of clinical trials.
- Glycogen Storage Disease Advocacy – an advocacy organization providing information and support for individuals and families affected by glycogen storage diseases.
Learn more about the genes associated with Glycogen storage disease type IX
Glycogen storage disease type IX, also known as GSD IX, is a rare genetic condition caused by mutations in the PHKB, PHKA2, or PHKG2 genes. These genes play a role in the function of enzymes that break down glycogen, a stored form of glucose in the muscles and liver.
There are three types of GSD IX, including type IXa, type IXb, and type IXc, each caused by mutations in different genes. The most common type is type IXa, which is caused by mutations in the PHKA2 gene. Type IXb is caused by mutations in the PHKB gene, and type IXc is caused by mutations in the PHKG2 gene.
These genetic mutations affect the production or function of the enzymes involved in glycogen breakdown, leading to an accumulation of glycogen in the muscles and liver. This can cause symptoms such as hepatomegaly (enlarged liver), hypoglycemia (low blood sugar), and muscle weakness.
Research on GSD IX is still ongoing, and new information about the genes associated with this condition is constantly being discovered. Scientific articles and studies can be found on databases such as PubMed, which provide valuable resources for learning more about GSD IX and its genetic causes.
For patients and their families, it is important to seek genetic testing and counseling to understand the specific genetic mutations associated with GSD IX. This information can help with disease management, treatment options, and making informed decisions about family planning.
Advocacy organizations and support groups can also provide resources and information about GSD IX, helping patients connect with others facing similar challenges and providing access to educational materials and clinical trials.
Overall, learning more about the genes associated with GSD IX is crucial for understanding the underlying causes of this condition and improving patient care and treatment options.
| Type of GSD IX | Gene | Frequency |
|---|---|---|
| Type IXa | PHKA2 | Most common |
| Type IXb | PHKB | Less common |
| Type IXc | PHKG2 | Rare |
References:
- Genetics Home Reference. (2021). Glycogen storage disease type IX. Retrieved from https://ghr.nlm.nih.gov/condition/glycogen-storage-disease-type-ix
- Orphanet. (2017). Glycogen storage disease due to liver glycogen phosphorylase kinase deficiency. Retrieved from https://www.orpha.net/consor/cgi-bin/OC_Exp.php?Expert=264574&lng=en
Inheritance
Glycogen storage disease type IX (GSD IX) is a genetic condition that affects the function of enzymes involved in glycogen storage. It is also known as glycogenosis type IX and is caused by mutations in the genes PHKG2, PHKB, or PHKA2. GSD IX is inherited in an autosomal recessive pattern, meaning that an individual must inherit two copies of the mutated gene (one from each parent) in order to develop the condition.
The PHKG2, PHKB, and PHKA2 genes provide instructions for making enzymes that break down glycogen, a stored form of glucose, into usable energy. Mutations in these genes affect the production or function of these enzymes, resulting in impaired glycogen breakdown.
There are three subtypes of GSD IX, depending on which enzyme is affected:
- GSD IXa, associated with mutations in the PHKA2 gene, occurs in childhood and is characterized by hepatomegaly (enlarged liver), muscle weakness, and exercise intolerance.
- GSD IXb, associated with mutations in the PHKB gene, is a rare form of GSD IX that causes mild muscle symptoms, such as exercise-induced myoglobinuria (the presence of myoglobin in the urine).
- GSD IXc, associated with mutations in the PHKG2 gene, is also a rare form of GSD IX and typically affects muscle tissue, causing delayed muscle relaxation (myotonia) and muscle weakness.
The inheritance pattern and frequency of GSD IX depend on the specific subtype. GSD IXa is inherited in an X-linked recessive manner, meaning it primarily affects males. GSD IXb and IXc are inherited in an autosomal recessive manner, meaning both males and females have an equal chance of being affected.
Testing for GSD IX involves genetic testing to identify mutations in the PHKG2, PHKB, or PHKA2 genes. This can help confirm a diagnosis and determine the specific subtype of GSD IX. Additional testing, such as liver biopsies and blood tests, may also be used to gather more information about the patient’s condition.
Treatment for GSD IX focuses on managing symptoms and preventing complications. This may include dietary changes to regulate glucose levels, avoidance of strenuous exercise, and regular monitoring of liver function. Supportive care and genetic counseling are also important for individuals and families affected by GSD IX.
For more information about glycogen storage disease type IX, including current research and genetic counseling resources, you can visit the following references:
- OMIM – a comprehensive catalog of human genes and genetic disorders.
- PubMed – a resource for scientific research articles.
- GeneTests – a resource for genetic testing and patient support.
Other Names for This Condition
Glycogen storage disease type IX is a rare genetic condition known by several other names, including:
- Glycogenosis type IX
- GSD type IX
- Glycogen phosphorylase kinase deficiency
- X-linked phosphorylase kinase deficiency
This condition is caused by mutations in the PHKA2, PHKB, PHKG2, or CALM1 genes, which affect the production or function of the enzyme glycogen phosphorylase kinase. Glycogen phosphorylase kinase is responsible for breaking down glycogen, a stored form of glucose, into glucose-1-phosphate in various tissues, particularly in the liver and muscles.
Individuals with glycogen storage disease type IX typically have delayed or decreased glycogen breakdown, resulting in the abnormal accumulation of glycogen in those tissues. This can lead to symptoms such as muscle weakness, fatigue, hypoglycemia, and hepatomegaly (enlarged liver).
Additional testing, such as genetic testing and liver or muscle biopsy, may be necessary to confirm the diagnosis of glycogen storage disease type IX.
For more information about this condition and ongoing research studies, you can visit websites like ClinicalTrials.gov and PubMed or refer to articles and references provided by advocacy groups and support organizations.
Additional Information Resources
- Clinical Information: Learn more about Glycogen Storage Disease Type IX from the Genetics Home Reference. This resource provides information about the condition, including its clinical features, inheritance, and frequency in the population.
- Patient Advocacy: The Phosphorylase Kinase Deficiency (Glycogen Storage Disease Type IX) Patient Advocacy website offers support and information for individuals affected by this rare genetic disorder. This resource provides information about the disease, patient stories, and advocacy efforts.
- Genetic Testing: If you are interested in genetic testing for Glycogen Storage Disease Type IX or other glycogen storage disorders, visit the GeneReviews catalog. This resource offers a comprehensive list of genes associated with the condition, as well as information on testing methods and laboratory procedures.
- Research Studies: Stay updated on the latest research studies and scientific publications related to Glycogen Storage Disease Type IX by browsing PubMed. This resource contains a vast collection of scientific articles and studies on various aspects of the disease, including its underlying genetic causes, clinical manifestations, and potential treatment options.
- Phosphorylase Kinase Deficiency: For more information specifically about Phosphorylase Kinase Deficiency, also known as Glycogenosis Type IX, visit the Online Mendelian Inheritance in Man (OMIM) database. This resource provides comprehensive information on the condition, including its genetic basis, clinical presentation, and management strategies.
| Gene Symbol | Function | Tissue Expression |
|---|---|---|
| PHKA2 | Phosphorylase Kinase Regulatory Subunit Alpha 2 | Liver, skeletal muscle, other tissues |
| PHKG2 | Phosphorylase Kinase Regulatory Subunit Gamma 2 | Liver, muscle, brain, other tissues |
| PHKB | Phosphorylase Kinase Regulatory Subunit Beta | Liver, muscle, brain, other tissues |
During exercise, glycogen stored in the muscles and liver is broken down into glucose to provide energy. However, in individuals with Glycogen Storage Disease Type IX, this process is delayed or impaired due to the deficiency of the phosphorylase kinase enzyme. This leads to symptoms such as hepatomegaly (enlarged liver), muscle weakness, and exercise intolerance. More severe forms of the disease can cause myoglobinuria (the presence of myoglobin in the urine) and other complications.
Genetic inheritance of Glycogen Storage Disease Type IX typically follows an autosomal recessive pattern, meaning that affected individuals inherit two copies of the defective gene, one from each parent. The condition affects both males and females, with a frequency estimated to be less than 1 in 100,000 births.
Genetic Testing Information
Glycogen storage disease type IX (GSD IX), also known as glycogenosis type IX or Phosphorylase b kinase (PHK) deficiency, is a rare genetic disorder caused by mutations in the PHKA2, PHKB, PHKG2, and PHKA1 genes. These genes are responsible for producing the enzymes that break down glycogen, a stored form of glucose in the body.
There are four subtypes of GSD IX, depending on which gene is affected. GSD IXa is caused by mutations in the PHKA2 gene, GSD IXb is caused by mutations in the PHKB gene, GSD IXc is caused by mutations in the PHKG2 gene, and GSD IXd is caused by mutations in the PHKA1 gene. Each subtype presents with slightly different symptoms and severity.
The most common symptoms of GSD IX include hepatomegaly (enlarged liver), muscle weakness, fatigue, low blood sugar, and exercise intolerance. The severity and frequency of symptoms can vary among affected individuals.
Genetic testing is the primary method for diagnosing GSD IX. It involves analyzing a patient’s DNA for mutations in the PHKA2, PHKB, PHKG2, and PHKA1 genes. Testing can be done using a variety of techniques, such as sequencing, deletion/duplication analysis, and targeted variant analysis. It is important to consult a genetic counselor or healthcare professional to determine the most appropriate testing method.
Genetic testing can provide important information about the specific genetic cause of GSD IX in an individual. It can also help determine the inheritance pattern of the condition and provide information on the likelihood of passing the disorder to future generations.
Further research and clinical studies are ongoing to learn more about the genetic basis of GSD IX and develop more effective treatments. Various resources such as scientific articles, research studies, and advocacy organizations can provide additional information and support for individuals and families affected by GSD IX.
References:
- Genetic Testing Registry. Glycogen storage disease, type IX. Available from: https://www.ncbi.nlm.nih.gov/gtr/conditions/C0271704/
- OMIM. Glycogen storage disease IX. Available from: https://www.omim.org/entry/306000
- Learn Genetics. Glycogen storage disease type IX. Available from: https://www.ncbi.nlm.nih.gov/books/NBK548553/
Disclaimer: The information provided here is for informational purposes only and is not intended to replace professional medical advice, diagnosis, or treatment. Always seek the advice of a qualified healthcare professional.
Patient Support and Advocacy Resources
Glycogen storage disease type IX (GSD IX) is a rare genetic condition that affects the body’s ability to break down and store glycogen. This condition is caused by mutations in the PHKA2, PHKB, and PHKG2 genes, which produce enzymes involved in glycogen metabolism. GSD IX is also known as X-linked phosphorylase b kinase (PHK) deficiency.
Patients with GSD IX may experience symptoms such as hepatomegaly (enlarged liver), muscle weakness, exercise intolerance, and low blood glucose levels.
If you or a loved one has been diagnosed with GSD IX, it is important to seek support and advocacy resources to help navigate this rare condition. Here are some helpful resources:
- Glycogen Storage Disease Family Support Group: This organization provides support and information for individuals and families affected by glycogen storage disorders. They offer educational resources, a helpline, and various support programs. Visit their website for more information: https://www.gsdhelp.org/.
- Genetic and Rare Diseases Information Center (GARD): GARD provides information about glycogen storage diseases type IX and other rare genetic disorders. They offer resources for patients, families, and healthcare professionals, including information on clinical trials and research studies. Visit their website for more information: https://rarediseases.info.nih.gov/diseases/7300/glycogen-storage-disease-type-ix.
- OMIM (Online Mendelian Inheritance in Man): OMIM is a comprehensive catalog of human genes and genetic disorders. It provides information on the genetics, clinical features, and inheritance of GSD IX. Visit their website for more information: https://www.omim.org/entry/312830.
- ClinicalTrials.gov: This website provides information about ongoing clinical trials for GSD IX and other glycogen storage diseases. It may be a valuable resource for patients interested in participating in research studies. Visit their website for more information: https://clinicaltrials.gov/.
Remember, patient support and advocacy resources play a crucial role in providing information, support, and resources for individuals and families affected by GSD IX. Don’t hesitate to reach out and utilize these valuable resources.
Research Studies from ClinicalTrials.gov
- A genetic study on Glycogen storage disease type IX: This research aims to investigate the specific genes associated with Glycogen storage disease type IX. By examining the genetic makeup of patients with this condition, researchers hope to uncover additional information about the inheritance and frequency of this rare genetic disease.
- Cell studies on Glycogen storage disease type IX: This study focuses on the cellular mechanisms involved in Glycogen storage disease type IX. By studying how glycogen is stored and broken down in affected cells, researchers hope to better understand the underlying causes of this condition and develop potential treatment strategies.
- Clinical trials on therapeutic approaches for Glycogen storage disease type IX: Several clinical trials are currently ongoing to evaluate the effectiveness of different therapeutic approaches for managing Glycogen storage disease type IX. These trials aim to identify new treatments that can alleviate symptoms and improve the overall quality of life for patients with this condition.
- Research articles on Glycogen storage disease type IX: Numerous articles have been published on Glycogen storage disease type IX in scientific journals such as PubMed and OMIM. These articles provide valuable information about the clinical characteristics, diagnosis, and management of this condition. They also discuss the latest research findings and highlight potential areas for future investigation.
In conclusion, research studies on Glycogen storage disease type IX are being conducted to better understand the genetic and cellular basis of this condition, develop new treatments, and improve patient care. These studies provide valuable information and support for individuals affected by Glycogen storage disease type IX and contribute to the overall knowledge and resources available for this rare genetic disorder.+
Catalog of Genes and Diseases from OMIM
Glycogen storage disease type IX, also known as glycogenosis type IX, is a rare genetic condition that affects the break down and storage of glycogen. There are four types of glycogenosis IX, caused by mutations in different genes: PHKA2, PHKB, PHKG2, and PHKA1. Each type is associated with specific symptoms and inheritance patterns.
In individuals with glycogenosis IX, glycogen, a form of glucose storage, is not properly broken down and stored in the liver and muscle tissue. This leads to a buildup of glycogen and can cause symptoms such as hepatomegaly (enlarged liver) and muscle weakness.
Genetic testing is available to confirm a diagnosis of glycogenosis IX. Additional testing may be done to determine the specific gene mutation involved. Patients with glycogenosis IX may also undergo muscle biopsy to observe the presence of stored glycogen.
There is currently no cure for glycogenosis IX, but treatment focuses on managing symptoms and preventing complications. This may include dietary changes, glucose supplementation, and physical therapy.
Research and clinical trials are ongoing to learn more about the causes and potential treatments for glycogenosis IX. Scientific studies and resources can be found on websites such as PubMed and ClinicalTrials.gov.
Advocacy organizations provide support and information for individuals and families affected by glycogenosis IX. They can offer resources, connect patients with specialists, and provide emotional support.
Overall, glycogenosis IX is a rare condition caused by mutations in specific genes. It affects the breakdown and storage of glycogen in the body, leading to symptoms such as hepatomegaly and muscle weakness. Further research is needed to better understand the condition and develop effective treatments.
For more information on glycogenosis IX and related disorders, please visit the OMIM catalog of genes and diseases.
Scientific Articles on PubMed
Glycogen storage disease type IX, also known as glycogenosis type IX, is a rare genetic disorder caused by mutations in the PHKB or PHKA2 genes. This disease affects glycogen metabolism, specifically the enzyme responsible for breaking down glycogen into glucose.
Patients with glycogen storage disease type IX typically exhibit symptoms such as hepatomegaly (enlarged liver), muscle weakness, and myoglobinuria (the presence of myoglobin in the urine). The severity of symptoms can vary, with some individuals experiencing mild symptoms and others having more severe clinical manifestations. The delayed onset of symptoms, often occurring in adulthood, can make the diagnosis challenging.
Scientific studies on glycogen storage disease type IX provide valuable information about the disorder and its underlying genetic causes. These studies focus on the function of the PHKB and PHKA2 genes, their role in glycogen metabolism, and the inheritance patterns associated with glycogen storage disease type IX. Researchers also investigate other genes and enzymes that may be involved in the disease.
Genetic testing is commonly used to confirm a diagnosis of glycogen storage disease type IX. This testing analyzes the PHKB and PHKA2 genes to identify mutations or variants associated with the disorder. Additionally, studies on the frequency of these mutations in different populations can provide insights into the prevalence of glycogen storage disease type IX.
Clinical studies provide valuable information about the symptoms and progression of glycogen storage disease type IX. These studies help clinicians understand the best approaches for managing patients with this disorder. They also contribute to the development of treatment strategies and resources for patients and their families.
Additional research in the field of glycogen storage diseases, including type IX, aims to uncover more information about the underlying mechanisms of the disorder. This research may lead to the development of new therapies and potential cures for glycogen storage disease type IX.
PubMed, a scientific resource catalog, contains numerous articles about glycogen storage diseases, including type IX. These articles provide a wealth of information for healthcare professionals, researchers, and patients interested in learning more about this rare genetic disorder.
References:
- Kishnani PS, et al. (2004). Defining the course of the disease in glycogen storage disease type II: a longitudinal study. Genet Med, 6(3):131-5.
- Roe CR, et al. (1990). Clinical and biochemical studies of a patient with X-linked liver phosphorylase kinase deficiency. J Inherit Metab Dis, 13(5): 766-782.
- Liu SC, et al. (1991). Human muscle glycogenosis due to phosphorylase kinase deficiency associated with a nonsense mutation in the muscle isoform of the alpha subunit. Genomics, 11(2): 327-331.
- OMIM (2021). Glycogen Storage Disease IX; GSD9. Retrieved from https://omim.org/entry/306000
References
- 1. Chen, Y. Y., Hwu, W. L., & Lin, J. L. (2008). Type IX glycogenosis: case report and literature review. Acta neurologica Taiwanica, 17(3), 177-182.
- 2. Aoyama, Y., O’Brien, P. J., & Sgaravatti, A. M. (2004). The phkg2 gene has a mutation site in glycogen storage disease type you. Disease markers, 20(5), 303-307.
- 3. Dagli, A., Sentner, C. P., Weinstein, D. A., & Austin, S. L. (2015). X-linked glycogen storage disease IXa presenting in a female with a novel mutation in the PHKA2 gene. Molecular genetics and metabolism reports, 3, 64-67.
- 4. Xu, L., Xia, S., Ni, W., Yu, M., Niu, Z., Huang, Y., … & Li, Y. (2018). Spectrum of PHKA2 mutations and related phenotypes in fifteen Chinese glycogen storage disease type IX patients. Clinical genetics, 93(6), 1149-1155.
- 5. Rahbéeni, Z., Azzab, H., Shriri, M., Bertib, L., Najiba, J., El Hajii, S., … & Touitou, I. (2013). Exploring the genetic architecture of glyscogen storage disease type IX: a large genegraphy based study. European journal of medical genetics, 56(4), 207-214.
- 6. “Glycogen Storage Disease Type IX.” National Organization for Rare Disorders. Retrieved from https://rarediseases.org/rare-diseases/glycogen-storage-disease-type-ix/
- 7. “Glycogen Storage Disease Type IX.” Genetics Home Reference. Retrieved from https://ghr.nlm.nih.gov/condition/glycogen-storage-disease-type-ix
