Huntington's disease

Definition

Huntington's disease is an inherited condition characterized by abnormal body movements, dementia, and psychiatric problems.

Causes, incidence, and risk factors

Huntington's disease is a progressive disorder involving wasting (degeneration) of nerve cells in the brain. The disorder was first described in 1872 by George Huntington, an American physician.

Huntington's disease is inherited as a single faulty gene on chromosome #4. There is a part of the gene that is repeated in multiple copies. The greater the number of repeats, the more likely it is that the person will develop symptoms and the greater the chance they will occur at a younger age. The disease may occur earlier and more severely in each succeeding affected generation because the number of repeats can increase.

Every child of a parent with the disorder has a 50% chance of inheriting Huntington's Disease. Symptoms do not usually appear until adulthood, typically between ages 35 and 50. Again, because onset depends on the number of repeats found in the gene, the disease may appear in younger people. In children it may resemble Parkinson's disease with rigidity, slow movements, and tremor.

There is progressive loss of mental function, including personality changes, and loss of cognitive functions such as judgment, and speech. Abnormal facial and body movements develop, including quick jerking movements. (The term chorea means "dance" and refers to the typical movements that develop.)

Symptoms

• behavior changes
  • irritability, moodiness
  • restlessness, fidgeting
  • antisocial behaviors
  • psychosis, paranoia, hallucinations
• facial movements, grimaces
• need to turn head to shift the gaze
• progressive dementia
  • loss of memory
  • loss of judgment
  • speech changes
  • loss of other functions (calculating, etc.)
  • personality changes
  • disorientation or confusion
• unsteady gait
• progressive development of abnormal (choreiform) movements
  • quick, sudden, jerking movements of arms, legs, face, trunk (movement, unpredictable - jerky)
  • movement, uncontrolled - slow

• speech impairment
• anxiety, stress, and tension
• difficulty swallowing

In children:

• slow movements
• tremor
• rigidity

Signs and tests

Examination may indicate progressive dementia and choreiform (chorea-like) movements. Reflexes may be abnormal. The gait is often "prancing" and wide. Speech may be hesitant or enunciation poor.

A head CT scan may show atrophy (loss of tissue), especially of deep brain (caudate) structures, or other abnormalities.

Other tests that may indicate Huntington's disease include:

• head MRI scan
• PET (isotope) scan of the brain
• DNA marker studies (gene studies that indicate the tendency to develop this disorder) may be available

Treatment

There is no cure for Huntington's disease, and there is no known way to stop progression of the disorder. Treatment is aimed at slowing progression and maximizing ability to function for as long as possible.

Medications vary depending on the symptoms. Dopamine blockers such as haloperidol or phenothiazine medications may reduce abnormal behaviors and movements. Reserpine and other medications have been used, with varying success. Drugs like Tetrabenazine and Amantadine are used to try to control extra movements. There has been some evidence to suggest that Co-Enzyme Q10 may minimally decrease progression of the disease.

Psychiatric illness, depression and suicide are common in Huntington's Disease. It is important for the caretaker and the physicians who care for a person with Huntington's Disease to monitor for symptoms and treat accordingly.

Symptomatic treatment for the dementia is similar to that used for any organic brain syndrome. Initially, reminders and aids may improve memory function. There is a progressive need for assistance and supervision, and 24-hour care may eventually be required.

Support Groups

Support groups for people affected by Huntington's disease are available and can help reduce the stress of dealing with this difficult diagnosis and its impact on reproductive and other life choices. See the Huntington's Disease Society of America for local information: http://www.hdsa.org/.

Expectations (prognosis)

Huntington's disease causes progressive disability. The disorder is usually fatal within 15 to 20 years. The cause of death is often infection, although suicide is also common. It is important to realize that not all patients with Huntington's Disease progress at the same pace and are equally affected. The number of repeats may determine severity. People with few repeats may have mild abnormal movements later in life and slow disease progression, whereas those with many repeats may be severely affected at a young age.

Complications

• loss of ability to care for self
• loss of ability to interact
• injuries to self or others
• increased risk of infections
• depression

Calling your health care provider

Call your health care provider if symptoms of this disorder develop. Sudden change in mental status may indicate development of a different disorder.

Prevention

Genetic counseling is advised if there is a family history of Huntington's disease. This may include DNA analysis of multiple family members. Since the odds that the child of a person with Huntington's disease will be affected are so high, people with the disorder may wish to consider adoption or forms of assisted reproduction that can reduce the chance that the disease will be passed on to their children.

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Huntington chorea ; chorea huntington; chorea disease huntington