HUNTINGTON'S DISEASE

Huntington’s disease is an inherited (genetic) disease that causes nerve cells in the brain to stop working properly. It is a progressive disease, meaning it continues to get worse over time. It leads to mental deterioration and loss of the ability to control major muscle movements.

An American doctor, George Huntington, first described the disease in 1872. It was commonly called Huntington’s chorea, from the Greek word for “dance,” because of the jerky, almost dancelike movements of people with the disease.

The genetic abnormality that causes Huntington’s disease was discovered in 1993. Each child of a parent with Huntington’s disease has a 50% chance of inheriting the illness. (Doctors call this an autosomal dominant disorder.) Huntington’s disease is relatively uncommon, affecting about 30,000 people in the United States. It affects people from all ethnic groups, and it affects males and females equally.

Varied symptoms

Huntington’s disease can affect intellectual ability, movement and emotional control. Symptoms include:

• Memory loss, inattention, dementia
• Involuntary twitching, clumsiness, dancelike involuntary movements (chorea), slurred speech, difficulty walking, difficulty swallowing
• Personality changes, depression, irritability, anxiety or lack of emotions (apathy)

Symptoms vary from person to person. They also can change over time, usually starting as subtle differences and progressing to profound disability. Symptoms typically begin between ages 35 and 50, though they can appear at any age, since the genetic abnormality that causes Huntington’s disease is present from birth.

The disease is rare in children. Symptoms begin before age 20 in less than 5% of cases. This is called juvenile Huntington’s disease. In children with Huntington’s disease, behavioral problems and mental deterioration are prominent, and rigidity and seizures are common. Huntington’s disease progresses more rapidly in children than in adults.

Testing to diagnose

Because the symptoms of Huntington’s disease begin subtly, diagnosis may not be made until the disease has started to worsen. Someone with a family history of Huntington’s disease who begins to have symptoms often is diagnosed based on a physical and neurological exam. A blood test is now available to detect the genetic abnormality that causes Huntington’s disease. Everyone who carries the Huntington’s disease gene eventually will develop the disease, but the test cannot predict when symptoms will begin.

Genetic testing carries enormous emotional and practical consequences, so you should discuss these issues with your doctor. Some people choose to be tested so they can make informed decisions about future plans (for example, career or marriage). Some hospitals offer prenatal testing. If you have a family history of Huntington’s disease, you can seek genetic counseling before getting pregnant to determine your risk of passing the gene to your children.

Many experts recommend that children under 18 should not get a genetic test, except in rare cases where there is an urgent medical need to do so. It is better to wait until children turn 18, so they can decide if they want to learn if they have the gene for Huntington’s.

Treatment, but no cure

There is no treatment to cure Huntington’s disease or slow its progression. However, there are therapies, including speech therapy and physical therapy, that can lessen the severity of symptoms. Antidepressants, neuroleptics, and other medications can help to control mood and involuntary movements.

Although there is no treatment to halt its progression, the course of the disease varies from person to person. For example, some people have mild symptoms that progress slowly while others have severe symptoms at a young age. There is some evidence that people who exercise and remain active tend to have milder symptoms and that their disease progresses more slowly than those who do not. However, everyone with Huntington’s disease ultimately becomes severely debilitated. They have difficulty eating and swallowing and are susceptible to infection, and it’s these complications that usually cause death.

For adults, the time from the beginning of symptoms until death is usually 10 to 20 years. In juvenile Huntington’s disease, the disease progresses more rapidly, with death usually occurring in 8 to 10 years. Research aimed at finding a cure has intensified since the gene for Huntington’s disease was discovered.

What does this mean for you?

If you have a family history of Huntington’s disease, discuss this with your doctor. You may want to consider genetic testing to determine whether you carry the Huntington’s disease gene. You also may want to understand the risks involved before having children.

Call your doctor if you experience any problems with emotional control, intellectual ability or movement. Although these symptoms are not specific to Huntington’s disease, and if you don’t have a family history of the disease, they are more likely to be symptoms of other conditions, they are worth discussing with your physician.

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