Huntington’s disease is a brain disorder that runs in families. The disease causes a loss of brain cellscalled neuronsin parts of the brain responsible for movement. It also affects parts of the brain that control thinking and behavior. About 30,000 people in the United States have a diagnosis of Huntington's disease.

Symptoms usually start when you're 30 to 50 years old. If Huntington's starts before age 20, it's called juvenile Huntington's disease. 

The main symptom of Huntington's is uncontrolled movement. These movements are known as chorea. Sometimes the disease is called Huntington’s chorea. Chorea movements affect your hands, feet, face, and trunk. The movements may be jerky or writhing.

Other symptoms include:

  • Stiff and abnormal body positions
  • Clumsiness
  • Slurred speech
  • Mood swings and changes in behavior and personality
  • Loss of ability to think clearly
  • Memory loss
  • Poor judgment
  • Depression
  • Loss of ability to swallow
  • Significant weight loss

Huntington's is a progressive disease. This means that symptoms lead to disability that tends to get worse over the 10- to 25-year period after diagnosis.  There's no cure and no treatment known to slow or stop its progression. However, various therapies can help manage symptoms.

Huntington's disease is caused by a change in a gene — known as a gene mutation that makes a protein in brain cells. This is the huntingtin gene. In people with Huntington's disease, the gene has been repeated and expanded abnormally. This gene mutation is passed down through families. If one of your parents has Huntington's, you have a 50 percent chance of developing it as well.  In addition to symptoms, a blood test to identify the genetic mutation helps doctors diagnose the disease.