Huntington's disease is a disorder passed down through families in which nerve cells in certain parts of the brain waste away, or degenerate.
Huntington's disease is caused by a genetic defect on chromosome 4. The defect causes a part of DNA, called a CAG repeat, to occur many more times than it is supposed to. Normally, this section of DNA is repeated 10 to 28 times. But in persons with Huntington's disease, it is repeated 36 to 120 times.
As the gene is passed down through families, the number of repeats tend to get larger. The larger the number of repeats, the greater your chance of developing symptoms at an earlier age. Therefore, as the disease is passed along in families, symptoms develop at younger and younger ages.
There are two forms of Huntington's disease.
If one of your parents has Huntington's disease, you have a 50% chance of getting the gene for the disease. If you get the gene from your parents, you will develop the disease at some point in your life, and can pass it onto your children. If you do not get the gene from your parents, you cannot pass the gene onto your children.
Behavior changes may occur before movement problems, and can include:
Abnormal and unusual movements include:
Dementia that slowly gets worse, including:
Additional symptoms that may be associated with this disease:
Symptoms in children:
The doctor will perform a physical exam and may ask questions about the patient's family history and symptoms. A neurological exam will also be done. The doctor may see signs of:
A head CT scan may show loss of brain tissue, especially deep in the brain.
Other tests that may show signs of Huntington's disease include:
Genetic tests are available to determine whether a person carries the gene for Huntington's disease.
There is no cure for Huntington's disease, and there is no known way to stop the disease from getting worse. The goal of treatment is to slow down the symptoms and help the person function for as long and as comfortably as possible.
Medications vary depending on the symptoms.
Depression and suicide are common among persons with Huntington's disease. It is important for all those who care for a person with Huntington's disease to monitor for symptoms and treat accordingly.
As the disease progresses, the person will need assistance and supervision, and may eventually need 24-hour care.
Huntington's Disease Society of America - www.hdsa.org
Huntington's disease causes disability that gets worse over time. Persons with this disease usually die within 15 to 20 years. The cause of death is often infection, although suicide is also common.
It is important to realize that the disease affects everyone differently. The number of CAG repeats may determine the severity of symptoms. Persons with few repeats may have mild abnormal movements later in life and slow disease progression, while those with a large number of repeats may be severely affected at a young age.
Call your health care provider if you develop symptoms of this disorder.
Genetic counseling is advised if there is a family history of Huntington's disease. Experts also recommend genetic counseling for couples with a family history of this disease who are considering having children.
Lang A. Other movement disorders. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier;2007:chap 434.
Jankovic J, Shannon KM. Movement disorders. In: Bradley WG, Daroff RB, Fenichel GM, Jankovic J, eds. Bradley: Neurology in Clinical Practice. 5th ed. Philadelphia, Pa: Butterworth-Heinemann Elsevier; 2008:chap 75.