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Disease Profile

Juvenile Huntington disease

Prevalence
Prevalence estimates on Rare Medical Network websites are calculated based on data available from numerous sources, including US and European government statistics, the NIH, Orphanet, and published epidemiologic studies. Rare disease population data is recognized to be highly variable, and based on a wide variety of source data and methodologies, so the prevalence data on this site should be assumed to be estimated and cannot be considered to be absolutely correct.
1-9 / 1 000 000

331 - 2,979

US Estimated

1-9 / 1 000 000

514 - 4,622

Europe Estimated

Age of onset

Adolescent

ICD-10

G10

Inheritance

Autosomal dominant A pathogenic variant in only one gene copy in each cell is sufficient to cause an autosomal dominant disease

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Autosomal recessive Pathogenic variants in both copies of each gene of the chromosome are needed to cause an autosomal recessive disease and observe the mutant phenotype

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X-linked
dominant X-linked dominant inheritance, sometimes referred to as X-linked dominance, is a mode of genetic inheritance by which a dominant gene is carried on the X chromosome.

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X-linked
recessive Pathogenic variants in both copies of a gene on the X chromosome cause an X-linked recessive disorder

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Mitochondrial or multigenic Mitochondrial genetic disorders can be caused by changes (mutations) in either the mitochondrial DNA or nuclear DNA that lead to dysfunction of the mitochondria and inadequate production of energy.

Multigenic or multifactor Inheritance involving many factors, of which at least one is genetic but none is of overwhelming importance, as in the causation of a disease by multiple genetic and environmental factors.

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Not applicable

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Other names (AKA)

JHD; Huntington disease, juvenile onset; Juvenile onset HD;

Categories

Nervous System Diseases

Summary

Juvenile Huntington disease (HD) is a less common, early-onset form of Huntington disease that begins in childhood or adolescence. It is a progressive disorder that causes the breakdown of brain cells in certain areas of the brain. This results in uncontrolled movements, loss of intellectual abilities, and emotional disturbances. Juvenile HD is defined by the onset of symptoms before age 20 years and accounts for 5-10% of all HD cases. It is inherited in an autosomal dominant pattern and is caused by a type of mutation called a trinucleotide repeat, in the HTT gene. Most often, children with juvenile HD inherit the mutation repeat from their fathers, although on occasion they inherit it from their mothers.[1][2] Juvenile Huntington disease has a rapid disease progression once symptoms present. There currently is no cure. Treatment is supportive and focused on increasing quality of life.[3] Most people with juvenile HD do not survive more than 10 to 15 years after symptoms begin.[2]

Symptoms

Signs and symptoms of juvenile Huntington disease (HD) begin in childhood or adolescence. Juvenile HD, like adult-onset HD, causes loss of thinking abilities, personality changes, impaired coordination, and emotional problems. Children and adolescents with juvenile HD often have a rapid decline in school performance as their ability to think and reason is weakened. Other common symptoms include dystonia, tremors, muscle twitching (myoclonus), stiffness of the leg muscles, clumsiness, slurred speech, and swallowing problems. Experiencing all of these symptoms can lead to feelings of anger, frustration, sadness, and fear, and may also lead to aggressive behavior. In some cases, behavior problems are the first symptom in a teenager with juvenile HD. Unlike in people with adult-onset HD, seizures are common (especially in children who have symptoms before age 10), and chorea may be only mild or not present at all. The symptoms in people with juvenile HD generally worsen more quickly than in those with adult-onset HD, often leading to loss of life within 10 to 15 years after symptoms begin.[2][3][4][5][6]

This table lists symptoms that people with this disease may have. For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed. This information comes from a database called the Human Phenotype Ontology (HPO) . The HPO collects information on symptoms that have been described in medical resources. The HPO is updated regularly. Use the HPO ID to access more in-depth information about a symptom.

Medical Terms Other Names
Learn More:
HPO ID
30%-79% of people have these symptoms
Abnormal involuntary eye movements
0012547
Abnormality of the cerebral white matter
0002500
Bradykinesia
Slow movements
Slowness of movements

[ more ]

0002067
Broad-based gait
Wide based walk
0002136
Chorea
0002072
Dementia
Dementia, progressive
Progressive dementia

[ more ]

0000726
Depressivity
Depression
0000716
Dystonia
0001332
Gait ataxia
Inability to coordinate movements when walking
0002066
Hyperactivity
More active than typical
0000752
Hyperreflexia
Increased reflexes
0001347
Irritability
Irritable
0000737
Neuronal loss in basal ganglia
0200147
Oral motor hypotonia
0030190
Rigidity
Muscle rigidity
0002063
Seizure
0001250
Weight loss
0001824
5%-29% of people have these symptoms
Cerebellar atrophy
Degeneration of cerebellum
0001272
Cerebellar vermis atrophy
0006855
Myoclonus
0001336
Progressive cerebellar ataxia
0002073
Ventriculomegaly
0002119
Percent of people who have these symptoms is not available through HPO
Abnormality of eye movement
Abnormal eye movement
Abnormal eye movements
Eye movement abnormalities
Eye movement issue

[ more ]

0000496
Autosomal dominant inheritance
0000006
Gliosis
0002171
Neuronal loss in central nervous system
Loss of brain cells
0002529
Personality changes
Personality change
0000751

Cause

Juvenile HD, like adult-onset HD, is caused by mutations in the HTT gene. This gene gives the body instructions for making a protein called huntingtin, which is thought to be important for nerve cells (neurons) in the brain. When the huntingtin protein does not function properly, it is thought to cause the death of neurons in certain areas of the brain, causing the symptoms of juvenile HD.[2]

The mutation in the HTT gene that causes HD involves a DNA segment known as a CAG trinucleotide repeat. This segment is made up of a series of three DNA building blocks (cytosine, adenine, and guanine) that normally appear multiple times in a row. In people without HD, the CAG segment is repeated 10 to 35 times within the gene.[2] In people with juvenile HD, the CAG segment is repeated more than 60 times.[1]

Diagnosis

Juvenile HD is diagnosed based on evaluation of symptoms, the family history, and genetic test results ideally by a pediatric neurologist. Neurological symptoms may need to be evaluated over several doctor appointments. No one symptom or group of symptoms is necessary for the diagnosis, but most children with juvenile HD have several symptoms by the time they are evaluated. Parents of children being evaluated may fear that their child's symptoms are due to juvenile HD, but it is important to remember that children can have developmental or neurological disorders that are unrelated to HD.[6][7]

In most cases, a child or teenager with juvenile HD has a parent with HD. However in some cases, the family history "appears" negative. This may be the case if a parent has died before symptoms began, if a parent has not yet been diagnosed, or if the father is not the biological father (non-paternity). If the family history is truly negative, other causes for the child's symptoms may be explored. If the family history is positive or the physician suspects the disease is present, genetic testing can be ordered to confirm or rule out the diagnosis of HD.[6][7]

Testing Resources

  • The Genetic Testing Registry (GTR) provides information about the genetic tests for this condition. The intended audience for the GTR is health care providers and researchers. Patients and consumers with specific questions about a genetic test should contact a health care provider or a genetics professional.

    Treatment

    Currently there is no cure for juvenile HD, and there is no way to slow or stop the progression of the disease. Treatment therefore aims to relieve symptoms and increase quality of life. A number of medications are available to help control or ease muscle stiffness, dystonia, and chorea. Physical and occupational therapy may also be helpful for temporarily easing these symptoms, developing strategies for moving around, and preventing falls. Medications are also available to help with seizures, as well as behavioral or psychiatric problems such as attention deficit or depression. Unfortunately, there are no medications known to improve thinking ability (cognitive function) in people with HD.

    The family of a child with juvenile HD should meet with school representatives to develop an Individual Education Plan (IEP), which should be reviewed frequently as the disease progresses.

    Organizations

    Support and advocacy groups can help you connect with other patients and families, and they can provide valuable services. Many develop patient-centered information and are the driving force behind research for better treatments and possible cures. They can direct you to research, resources, and services. Many organizations also have experts who serve as medical advisors or provide lists of doctors/clinics. Visit the group’s website or contact them to learn about the services they offer. Inclusion on this list is not an endorsement by GARD.

    Organizations Supporting this Disease

      Social Networking Websites

        Learn more

        These resources provide more information about this condition or associated symptoms. The in-depth resources contain medical and scientific language that may be hard to understand. You may want to review these resources with a medical professional.

        Where to Start

          In-Depth Information

          • GeneReviews provides current, expert-authored, peer-reviewed, full-text articles describing the application of genetic testing to the diagnosis, management, and genetic counseling of patients with specific inherited conditions.
          • Medscape Reference provides information on this topic. You may need to register to view the medical textbook, but registration is free.
          • The Monarch Initiative brings together data about this condition from humans and other species to help physicians and biomedical researchers. Monarch’s tools are designed to make it easier to compare the signs and symptoms (phenotypes) of different diseases and discover common features. This initiative is a collaboration between several academic institutions across the world and is funded by the National Institutes of Health. Visit the website to explore the biology of this condition.
          • Online Mendelian Inheritance in Man (OMIM) is a catalog of human genes and genetic disorders. Each entry has a summary of related medical articles. It is meant for health care professionals and researchers. OMIM is maintained by Johns Hopkins University School of Medicine. 
          • Orphanet is a European reference portal for information on rare diseases and orphan drugs. Access to this database is free of charge.
          • PubMed is a searchable database of medical literature and lists journal articles that discuss Juvenile Huntington disease. Click on the link to view a sample search on this topic.

            Selected Full-Text Journal Articles

              References

              1. Warby SC, Graham RK &Hayden MR. Huntington Disease. GeneReviews. December 11, 2014; https://www.ncbi.nlm.nih.gov/books/NBK1305/.
              2. Huntington disease. Genetics Home Reference. June 2013; https://ghr.nlm.nih.gov/condition/huntington-disease.
              3. Juvenile Onset HD. Huntington's Disease Society of America. https://hdsa.org/living-with-hd/juvenile-onset-hd/. Accessed 3/11/2016.
              4. Huntington's Disease: Hope Through Research. National Institute of Neurological Disorders and Stroke (NINDS). https://www.ninds.nih.gov/Disorders/Patient-Caregiver-Education/Hope-Through-Research/Huntingtons-Disease-Hope-Through. Accessed 1/11/2018.
              5. Revilla FJ. Huntington Disease. Medscape Reference. April 20, 2017; https://emedicine.medscape.com/article/1150165-overview#showall.
              6. What is Juvenile Huntington Disease?. Huntington Society of Canada. https://www.huntingtonsociety.ca/learn-about-hd/what-is-juvenile-huntington-disease/. Accessed 1/12/2018.
              7. Nance M. The Juvenile HD Handbook: A Guide for Families and Caregivers – Second Edition. The Diagnosis of HD in a Child. 2007; 106. https://www.hdsa.org/images/content/1/1/11702.pdf.
              8. Nance M, Jones R, Imbriglio S, Gettig B. Juvenile Huntington's Disease. Huntington’s Disease Society of America. 2001; https://hdsa.org/wp-content/uploads/2015/02/juvenile_guide.pdf.
              9. Huntington Disease. National Institute of Neurological Disorders and Stroke (NINDS). August 2010; https://www.ninds.nih.gov/disorders/huntington/detail_huntington.htm.

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