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Huntington Disease
Sunday, 20 July 2003
Wednesday, 17 May 2006
Huntington Chorea

What

Huntington disease (HD) is an inherited, progressive disorder of the central nervous system. It is characterized by a variety of symptoms including problems with voluntary and involuntary movement, psychiatric disturbances, and cognitive decline.

Who

The symptoms of HD are usually first seen in adults between the ages of 35 to 44 years. However, juvenile onset HD (starting younger than 21 years), accounts for five to ten percent of Huntington disease in the United States.

Signs and Symptoms

Onset of Huntington Disease is often subtle, and it progresses slowly over time. Early symptoms may be characterized by minor involuntary movements, clumsiness, or mood changes such as irritability or depression. As time progresses, the abnormal movements become more significant. Initially movements may be one-sided, more prominent in the face than the legs, and progress from mild fidgeting to grimacing, tongue smacking, indistinct speech (dysarthria), and slow-twisting snake-like movements (athetoid movements). Slow movement (bradykinesia) is often accompanied by stiffness and affected people may develop problems with swallowing. In addition to these movements, people with HD often experience a decline in cognitive abilities, and have trouble with forgetfulness, concentration, and slow mental processing. Individuals with HD may also develop significant personality changes and depression. Early onset (childhood and juvenile) HD presents somewhat differently. These children also develop cognitive decline, but may also have severe stiffness (rigidity) and about one third of children may develop epileptic seizures. The progression of the disease in younger children is often faster than in adults.

Possible Causes

Huntington Disease is caused by an inherited mutation called a “CAG repeat” of the HD gene. The size of the CAG repeat may grow larger with successive generations, leading to an earlier age of disease onset. This process is called anticipation. The affected gene is passed on from parents to children as an autosomal dominant trait. This means that only one affected gene from one parent is necessary to pass on the disease, with a 50% chance that children of affected adults with inherit the disease. How exactly the mutated gene and altered protein cause the symptoms of HD is not known.

Diagnosis

The diagnosis of HD is made in those with a family history of HD, by the use of a highly sensitive gene test. Molecular DNA testing can be performed that reveals an increased number of CAG repeats in chromosome 4. The altered gene produces a longer than usual “huntingtin” protein, which is responsible for the features of HD. The Huntington's Outreach Project for Education at Stanford provides a very good explanation of how this testing is done. The website link is at the end of this article. Brain imaging studies (CT, MRI, PET scans) are usually not useful for the diagnosis of HD, but may be used to rule out other causes of a patient’s symptoms if the diagnosis of HD is not clear.

Treatment

There is no known cure for Huntington Disease, thus treatment is directed toward coping with the symptoms. Medications are available to help with movement problems, personality changes and depression as well as other symptoms of HD. A variety of other therapies are currently under investigation. Supportive care with special diets, equipment and nursing is often very helpful to those with HD. Many individuals find local HD support groups are quite valuable to those afflicted with HD as well as their families.

Prognosis

The earlier the onset of juvenile HD the faster it usually progresses. In the juvenile form, progression of the disease is more rapid than in the adult onset form. Often, death from juvenile HD occurs within 10 years of onset, as opposed to 10-25 years in adult-onset HD.

Connect with other parents

In the spirit of community and support, Madisons Foundation offers the unique service of connecting parents of children with rare diseases. If you would like to be connected to other parents of children with this disease, please fill out this brief form.

Weblinks

Huntington's Disease Society of America (HDSA)
Brief summary of HD with other downloadable information for families, up to date research news, links to other HD sites. Email: hdsainfo@hdsa.org

Stanford HOPES 
This site is an excellent resource, with an illustrated understandable explanation of the biologic basics of HD as well as details about various signs and symptoms of HD. It also contains information specifically about juvenile HD.

Huntington’s Disease Advocacy Center (HDAC)
Website constructed by families with HD, with a focus on personal stories and experiences with HD

Google Search for Huntington Disease

References and Sources

Haigh B, Huq M, Hayden. Huntington Disease www.genetests.org www.hdsa.org/ www.hdfoundation.org/index/html www.stanford.edu/group/hopes/ ww.ninds.nih.gov/health_and_medical/disorders/huntington.htm www3.ncbi.nlm.nih.gov/htbin-post/Omim/dispmim?143100