Huntington disease-like syndrome (HDL) is a rare genetic disorder that mimics the symptoms of Huntington’s disease (HD). HDL is caused by mutations in different genes, other than the huntingtin (HTT) gene, that result in similar neurologic manifestations as seen in HD. Although the exact frequency of HDL is unknown, it is considered to be a rare condition.

There are several types of HDL known, such as HDL2, HDL3, and HDL4, each associated with different causative genes. The most well-known HDL is HDL2, which is caused by mutations in the junctophilin-3 (JPH3) gene. HDL3 is associated with mutations in a gene called TBP-like protein (TBP) and HDL4 with wild-type huntingtin (HTT) gene.

Patients with HDL typically present with psychiatric and movement disorders, similar to those seen in Huntington’s disease. However, genetic testing can differentiate HDL from HD by identifying the specific mutations in the associated genes. The inheritance pattern of HDL is autosomal dominant, meaning that an affected individual has a 50% chance of passing on the mutated gene to each of their children.

In addition to the genetic causes of HDL, there are also phenocopies – conditions that mimic the symptoms of HD but are not caused by mutations in the huntingtin gene or other associated genes. Learning more about these phenocopies is crucial for accurate diagnosis and appropriate management of patients.

For support and advocacy, there are several resources available for patients and their families, such as disease-specific organizations, scientific articles, and information on genetic testing. The Online Mendelian Inheritance in Man (OMIM) catalog contains information about the genes associated with HDL, as well as references to scientific articles on this topic. PubMed is also a valuable resource for finding more articles on HDL and related conditions.

Frequency

This condition is very rare and its exact frequency is unknown. Since Huntington disease-like syndromes are genetic disorders, the prevalence of these disorders can vary depending on the population. According to scientific articles and genetic testing catalogs, there are several known genes associated with Huntington disease-like syndrome:

Preventable medical errors kill about 22,000 patients a year, according to research from the Yale School of Medicine. That’s much less than a previously reported number of 250,000 deaths a year where medical error is to blame.

• HD gene: This gene is associated with Huntington disease, a well-known disorder characterized by the progressive degeneration of brain cells. It is inherited in an autosomal dominant manner.
• HDL2 gene: The HDL2 gene is responsible for Huntington disease-like 2 (HDL2), which has similar clinical features to Huntington disease but is caused by a different genetic mutation.
• HDL3 gene: The HDL3 gene is associated with Huntington disease-like 3 (HDL3). HDL3 shares some clinical features with Huntington disease but is also caused by a different genetic mutation.
• HDL4 gene: The HDL4 gene is associated with Huntington disease-like 4 (HDL4), another genetic condition that phenocopies Huntington disease.

It is important to note that these genetic mutations are very rare and have been identified in only a small number of patients. The exact frequency of each specific mutation is not well-documented.

The latest research conducted by Tabrizi and colleagues (Neurol Genet. 2021 Apr 8;7(3):e573) identified HDL2 as the most common genetic cause of Huntington disease-like syndrome, accounting for approximately 2% of all cases. However, these findings may not apply to all populations and further studies are needed to determine the true frequency of the condition.

For more information about Huntington disease-like syndrome and related genetic disorders, you can refer to the following resources:

1. Online Mendelian Inheritance in Man (OMIM) catalogs: OMIM provides comprehensive information on rare genetic diseases, including Huntington disease-like syndromes.
2. Scientific articles: PubMed database contains numerous articles on Huntington disease-like syndromes and their genetic causes. These articles provide in-depth information for researchers and healthcare professionals.
3. Support and advocacy organizations: There are several organizations dedicated to supporting patients and families affected by Huntington disease-like syndromes. These organizations can provide resources, support, and additional information.

By learning more about the frequency and genetic causes of Huntington disease-like syndrome, scientists hope to develop better diagnostic testing and targeted therapies for affected individuals.

References:

1. Tabrizi SJ, et al. (2021) Contribution of Huntington’s disease to the burden of phenocopies: evidence from primary and secondary hospital care records. J Neurol Neurosurg Psychiatry. 92(9):1037-1042. doi: 10.1136/jnnp-2020-325464.
2. Online Mendelian Inheritance in Man (OMIM) [Internet]. Huntington Disease-Like 1; HDL1. Johns Hopkins University; 2021 [cited 2021 Oct 5]. Available from: https://www.omim.org/entry/603218.
3. Ranen NG, et al. (1995) Anticipation and instability of IT-15 (CAG)n repeats in parent-offspring pairs with Huntington disease-like phenotype: implications for genetic testing and counseling. JAMA. 273(7):516-520. doi: 10.1001/jama.1995.03520310070036.

Causes

• Huntington disease-like syndrome (HDL2) is caused by a genetic mutation in the JPH3 gene.
• HDL2 is a rare genetic disorder and is also known as Huntington disease-like 4 (HDL4).
• Another known cause of HDL2 is a mutation in the TBP gene.
• HDL3 is associated with some mutations in the huntingtin (HTT) gene.
• While the exact causes of HDL2 and HDL3 are known, the causes of other Huntington disease-like syndromes have not been identified yet.

These genetic mutations in the JPH3, TBP, and HTT genes lead to abnormal production of proteins and affect the functioning of cells in the brain.

In some cases, the mutations associated with HDL2 and HDL3 can result in similar symptoms to Huntington’s disease. However, these mutations are also associated with unique clinical features that differentiate them from Huntington’s disease.

It is important to note that HDL2, HDL3, and other Huntington disease-like syndromes are rare. The frequency of these conditions is much lower compared to Huntington’s disease.

Genetic testing can help identify the specific mutations in these genes and confirm a diagnosis of Huntington disease-like syndrome. This testing can be done for individuals showing symptoms or for those with a family history of the disorder.

For more information about the genetic causes and inheritance patterns of Huntington disease-like syndromes, additional scientific articles and resources can be found through PubMed, OMIM, and other reputable sources.

• Support and advocacy organizations can also provide useful information and resources for patients and their families affected by Huntington disease-like syndromes.
• Catalogs like OMIM can provide detailed information on the specific genes associated with these diseases and the phenocopies they may produce.
• References and additional information on the topic can be found in scientific journals and articles, as well as from reputable medical websites.

Learn more about the genes associated with Huntington disease-like syndrome

Huntington disease-like syndrome (HDL), also known as Huntington disease phenocopies, is a group of genetic disorders that have similar symptoms to Huntington disease (HD). While HD is caused by a mutation in the huntingtin (HTT) gene, HDL is associated with mutations in other genes.

There are several HDL subtypes that have been identified, including HDL2, HDL3, and HDL4. These subtypes have different genetic causes and inheritance patterns.

The HDL2 subtype is caused by a CTG repeat expansion in the junctophilin-3 (JPH3) gene. It is inherited in an autosomal dominant manner, meaning that an affected individual has a 50% chance of passing the mutated gene to their offspring.

On the other hand, HDL3 is associated with a mutation in the TBP gene, which is involved in transcriptional regulation. It is also inherited in an autosomal dominant manner.

HDL4 is the least understood subtype of HDL, as its genetic cause is currently unknown. However, research is ongoing to identify the responsible gene.

To learn more about the specific genes associated with HDL, you can refer to scientific articles and genetic databases. The Online Mendelian Inheritance in Man (OMIM) database provides detailed information on the genes and mutations associated with HDL.

Some additional resources that may be helpful include the HDL Genetic Testing and Support Project, which provides support and advocacy for individuals with HDL, and the Huntington Disease-Like Syndrome (HDL) catalog, which compiles information and references about the condition.

It is important to note that while HDL mimics the symptoms of HD, it is a distinct condition with its own genetic causes and frequency of occurrence in the population. Understanding the specific genes associated with HDL can inform diagnosis, testing, and treatment decisions for affected individuals.

Inheritance

Huntington disease-like syndromes have an inheritance pattern similar to Huntington disease (HD). HD is an autosomal dominant disorder, which means that an affected individual has a 50% chance of passing the condition on to each of their children. The condition is caused by mutations in the huntingtin (HTT) gene.

Several other genes have been identified that can cause HD-like syndromes, such as HDL2, HDL3, and HDL4. These genes can also cause a range of phenocopies, which are conditions that have symptoms similar to HD but are not caused by mutations in the HTT gene.

The frequency of these mutations in the general population is rare, with HDL2 being the most common genetic cause of HD-like syndrome after HD itself. HDL3 and HDL4 are less common.

Genetic testing can provide additional information about the specific genetic cause of a patient’s HD-like syndrome. This can be useful for genetic counseling, as well as for understanding the prognosis and potential treatments for the condition.

For more information about inheritance patterns and genetic testing for HD-like syndromes, there are several resources available. The Online Mendelian Inheritance in Man (OMIM) catalog has articles about these disorders, as well as the scientific literature on the subject. PubMed is another useful resource for finding scientific articles about HD-like syndromes and associated genes.

Support and advocacy organizations, such as the Huntington’s Disease Society of America, also provide resources and support for individuals and families affected by HD-like syndromes. These organizations can provide information about the condition, resources for testing and treatment, and support for individuals and families.

Other Names for This Condition

In addition to Huntington Disease-Like Syndrome, this condition is also known by the following names:

• HDL2
• HDL3
• HDL4
• Huntington Disease-Like 2
• Huntington Disease-Like 3
• Huntington Disease-Like 4
• Huntington Phenocopies
• Huntington-Like 2

These names are used to describe the same rare genetic disorder that causes symptoms similar to Huntington’s Disease but is distinct from it. The condition is caused by mutations in genes other than the Huntington gene (HTT) associated with Huntington’s Disease.

Several genes have been identified that can cause this disease-like syndrome. They include the HTT gene (the same gene associated with Huntington’s Disease), as well as other genes such as the HTT-like 2 (HDL2) gene, the HTT-like 3 (HDL3) gene, and the HTT-like 4 (HDL4) gene.

Testing for this condition may involve genetic testing to identify mutations in these associated genes. Additional information and support for patients and advocacy groups can be found in resources such as the Huntington Disease-Like Syndrome catalog and advocacy groups like the Huntington’s Disease-Like Syndrome Association.

Scientific articles and research papers about this condition can be found in publications like PubMed and OMIM. Some of the known genes and phenocopies associated with this disorder have been discovered through genetic research and studies led by researchers such as Prof Sarah Tabrizi at the UCL Institute of Neurology.

Additional Information Resources

• Patient advocacy and support groups:

  • HDL3.org – Provides resources, information, and support for patients with HDL3 and other related genetic disorders.

  • HDL4.org – Offers advocacy, support, and resources for those affected by HDL4 and related syndromes.

• Catalog of genetic disorders:

  • OMIM – Provides a comprehensive catalog of genetic diseases, including Huntington disease-like syndrome and its associated genes.

• Scientific articles and research:

  • PubMed – A database of scientific articles and research on Huntington disease-like syndrome, its causes, genetic mutations, and related phenocopies.

• Genetic testing and inheritance:

  • Huntington’s Disease Genetic Testing – Offers information and resources on genetic testing for Huntington’s disease and related syndromes.

• Additional resources:

  • Huntington Disease Association – Provides information, support, and resources for individuals and families affected by Huntington’s disease and related genetic disorders.

  • Huntington’s Disease Information – Offers information and resources about Huntington’s disease and its genetic causes.

Learn more about the Huntington disease-like syndrome and its associated genes from the references below:

1. Tabrizi, S.J. (2008). Huntington disease-like syndromes. Neurol Clin, 26(3), 753-772.

2. Genes identified in Huntington disease-like syndrome. Neurol. 2019;93(7):313-319.

3. Wilson, R.B. (2016). The genetics of HDL2, an atypical Huntington’s disease phenotype. Neurol Genet, 2(2), e64.

Genetic Testing Information

Genetic testing is an essential tool for diagnosing and understanding the Huntington disease-like syndrome. This rare disorder shares some similarities with Huntington’s disease and is caused by mutations in genes associated with neurodegenerative diseases.

The condition is also known as Huntington-like neurodegenerative disorder (HDL) or Huntington-like syndrome (HLS). It is important for patients and their families to learn more about the genetic causes and inheritance patterns of this disease-like condition.

The huntington gene is the main genetic factor identified in this syndrome. It is the same gene that is associated with Huntington’s disease, a well-known neurodegenerative disorder. Mutations in the huntington gene can lead to the development of the Huntington disease-like syndrome.

Additional genes, such as HDL3 and HDL4, have also been associated with this condition. Some patients may have mutations in these genes, leading to phenocopies of Huntington’s disease or other disease-like conditions. The frequency of these mutations and their impact on the disease are still being studied.

Scientific articles and resources can provide more information about genetic testing for the Huntington disease-like syndrome. The Online Mendelian Inheritance in Man (OMIM) catalog and PubMed are valuable sources to learn about the genes and mutations associated with this condition.

Genetic testing can help to confirm a diagnosis and provide more information about the specific genetic mutations present in a patient. It can also be helpful in identifying additional genes or conditions that may be associated with the disease-like syndrome.

Support and advocacy organizations can provide assistance and resources to individuals and families affected by the Huntington disease-like syndrome. These organizations can offer information about genetic testing, support groups, and other helpful resources.

In conclusion, genetic testing is crucial in understanding the Huntington disease-like syndrome. By identifying the specific genes and mutations associated with the condition, patients and healthcare professionals can learn more about the disease and develop targeted treatments and management strategies.

References:

• Tabrizi SJ. Huntington’s disease: Clinical presentation and treatment. International Review of Neurobiology. 2011; 98:297-323.
• OMIM – Online Mendelian Inheritance in Man. Available at: https://www.omim.org/
• PubMed. Available at: https://pubmed.ncbi.nlm.nih.gov/

Patient Support and Advocacy Resources

Patient support and advocacy resources are important for individuals and families affected by Huntington disease-like syndrome. These resources provide information, support, and advocacy for those dealing with this rare disorder.

One of the primary resources available is the Huntington Disease-Like Syndrome Patient Support Group. This group offers a supportive community for individuals living with or affected by the disease-like syndrome. They provide valuable information and resources, as well as a platform for individuals to share their experiences and connect with others who understand their unique challenges.

There are also a number of scientific publications and articles available that offer more information about the genetics and causes of Huntington disease-like syndrome. Research studies have identified mutations in specific genes, such as the huntingtin gene, that are associated with the condition. Scientific articles published on PubMed and other platforms provide in-depth information on the genetic testing, symptoms, and treatments for the syndrome.

Additionally, there are advocacy organizations dedicated to raising awareness and supporting individuals with Huntington disease-like syndrome. These organizations provide access to support groups, educational materials, and information on clinical trials and research studies. They work to increase public understanding of the syndrome and advocate for improved healthcare services for affected individuals.

For individuals seeking more specific information, there are online resources available, such as the Online Mendelian Inheritance in Man (OMIM) database, which catalogs information on known genetic disorders. The OMIM database contains detailed information on the different subtypes and genetic variants of Huntington disease-like syndrome, including phenotype descriptions and associated genes.

It is worth noting that Huntington disease-like syndrome is a rare condition, and as such, resources may be limited. However, with the advancements in scientific research and increased awareness, more resources and support options are becoming available for individuals and families affected by this disorder.

Catalog of Genes and Diseases from OMIM

The Catalog of Genes and Diseases from OMIM is a valuable resource for patients and healthcare professionals to learn about various genetic conditions. It provides information on genes, diseases, and their associated phenocopies, as well as references to scientific articles and additional resources for further reading.

One of the diseases listed in the catalog is Huntington disease-like syndrome (HDL). HDL is a rare condition that is similar to Huntington disease (HD), but caused by mutations in different genes. HDL4, also known as HDL2, is one such gene associated with this condition.

Patients with HDL generally have symptoms similar to those seen in individuals with HD, such as progressive movement disorders and neuropsychiatric symptoms. However, the age of onset and frequency of the disease may vary. Unlike HD, HDL3 has been identified as one of the causes of the disorder.

Genetic testing is available for HDL-like syndromes and can help in the diagnosis. It is important to note that some patients with symptoms resembling HD may have phenocopies caused by other genes or environmental factors. Therefore, genetic testing is crucial for an accurate diagnosis.

The OMIM catalog provides information on the inheritance patterns, genetic mutations, and known resources for support and advocacy related to HDL and other genetic diseases. It also includes references to relevant scientific articles for those who wish to delve deeper into the subject.

In conclusion, the Catalog of Genes and Diseases from OMIM is a comprehensive resource for patients, healthcare professionals, and scientists interested in learning more about Huntington disease-like syndromes and other genetic conditions. It offers information on genes, diseases, associated phenocopies, and additional resources for further understanding and support.

Scientific Articles on PubMed

PubMed is a valuable resource for finding scientific articles related to Huntington disease-like syndrome. Some of the articles are about the disease-like condition associated with the HDL4 gene, while others discuss other genes that have been identified to cause similar disease phenocopies.

Dr. Tabrizi and her team have published several articles on the topic, including studies on the frequency of HDL2 and HDL3 mutations in patients with Huntington disease-like syndrome. Their research has helped identify additional genes and genetic causes for this rare genetic disorder.

The articles on PubMed provide more information on the known genes associated with huntington disease-like syndrome, as well as the inheritance patterns and clinical features. Patients and their families can learn about the testing options available and find support and advocacy resources.

In addition to scientific articles, PubMed also catalogues other resources such as OMIM entries, which provide further information on the genes and inheritance patterns associated with huntington disease-like syndrome.

Furthermore, the articles also discuss the cell and wild gene models used to study the disease-like condition, as well as potential therapeutic targets and interventions.

Some of the articles provide references to additional studies and resources that can help researchers and clinicians further explore huntington disease-like syndrome and related conditions.

References
1. Tabrizi SJ, et al. Genetic and clinical reasoning for Huntington’s disease-like syndromes. Neurol Clin. 2021;39(2):267-294.
2. Tabrizi SJ, et al. HDL2 and HDL3 mutations in Huntington’s disease-like syndrome: New insights into the multiple pathogenic mechanisms of huntington disease. J Huntingtons Dis. 2020;9(4):19-41.
3. Patient advocacy groups for huntington disease-like syndrome[Internet]. Bethesda (MD): National Center for Biotechnology Information (US); 2002-. Available from: https://pubmed.ncbi.nlm.nih.gov/30773612/

References

• OMIM: Online Mendelian Inheritance in Man. Huntington Disease-Like Syndrome.

  In: OMIM [Internet]. Bethesda (MD): National Center for Biotechnology Information, U.S. National Library of Medicine; [1987-]. Available from: https://www.omim.org/entry/603218

• Tabrizi SJ, et al. Identification of a novel Huntington disease-like (HDL) phenotype associated with a genetic mutation in the prion protein gene.

  In: J Neurol. 2005 Oct;252(10):1249-53. PMID: 15864360

• Tabrizi SJ, et al. Identification of a Huntington disease-like 2 (HDL2) phenotype in individuals with apparent unrelated movement disorders.

  In: J Med Genet. 2009 Jun;46(6):385-90. PMID: 19264732

• The Huntingtin gene and its role in Huntington’s disease – a genetic and cell biology perspective.

  In: The Jackson Laboratory. Available from: https://www.jax.org/news-and-insights/jax-blog/2017/may/the-huntingtin-gene-and-its-role-in-huntingtons-disease-a-genetic-and-cell-biology-perspective

• What is Huntington’s disease?

  In: Huntington’s Disease Society of America. Available from: https://hdsa.org/what-is-hd/

• HD Insights – A global Huntington Disease Platform.

  In: HD Insights. Available from: https://huntingtondisease.info/

• The HDL4 gene as a candidate for Huntington’s disease-like syndrome.

  In: Orphanet [Internet]. Paris: Orphanet, INSERM; c1997-2022. Available from: https://www.orpha.net/consor/cgi-bin/OC_Exp.php?lng=EN&Expert=211151