Huntington’s disease is a severe hereditary disorder of the nervous system. It destroys brain cells and causes involuntary body movements, mental disturbances, and eventual death. The disorder was named for George Huntington, an American physician, who first described it in 1872. The condition is also called Huntington’s chorea (see Chorea ).
The symptoms in most cases of the disease begin when the person is from 35 to 40 years old. But some cases start in childhood or old age. Patients live an average of 15 years after the first symptoms of the disease appear.
The first physical symptom of the disease may be slight clumsiness or restlessness. Later, muscles in the face and hands begin to move involuntarily. Involuntary facial movements include pouting of the lips, irregular raising of the eyelids, and puffing out of the cheeks. As Huntington’s disease progresses, the involuntary movements become stronger and eventually involve the whole body. The head, shoulders, arms, and legs jerk uncontrollably. When the patient walks, voluntary and involuntary movements combine and produce lurching, dancelike steps. Early mental symptoms of the disease include dullness and irritability, and carelessness about personal grooming. The disease gradually destroys the patient’s intellect and memory. Severe mental illness may develop.
The patient may finally lose all muscle control and mental ability. Death results from pneumonia, choking, or other complications of the disease. Some patients with Huntington’s disease become depressed and commit suicide.
Huntington’s disease is caused by an abnormal gene located on one of a pair of chromosomes designated as chromosome 4. The gene normally provides the instructions for making a protein, called huntingtin, which is necessary for brain development. The abnormal gene contains an error that corrupts the protein, making it toxic to brain cells. Anyone who inherits this gene will eventually be stricken by the disorder as the toxic protein builds up in their brain. Each child of a patient with the disease has a 50 percent chance of inheriting the gene.
Experts estimate that of every 100,000 people, 2 to 9 have the gene for the disease. Researchers have developed a genetic test to identify people who carry the gene but who have not yet developed the disease. Huntington’s disease has no cure. However, many of the symptoms of Huntington’s disease may be eased by the use of drugs and by other forms of treatment. Scientists are developing promising new treatments aimed at ceasing the function of the abnormal huntingtin gene.
