Huntington's disease is a rare, inherited disease that causes the progressive breakdown of nerve cells in the brain. Huntington's disease has a broad impact on a person's functional abilities and usually results in movement, cognitive and psychiatric disorders.
Huntington's disease symptoms can develop at any time, but they often first appear when people are in their 30s or 40s. If the condition develops before age 20, it's called juvenile Huntington's disease. When Huntington's develops early, symptoms are somewhat different and the disease may progress faster. Medications are available to help manage the symptoms of Huntington's disease. But treatments can't prevent the physical, mental and behavioral decline associated with the condition.
Huntington’s is caused by a defect in a single dominant gene. If one parent has the disease, every child has a 50/50 chance of having it, too. About 30,000 people in the United States have it, and another 200,000 are at risk. It is the disease that killed the folk singer Woody Guthrie in 1967.
The gene contains the blueprint for a protein that the researchers named Huntingtin. Its role in the brain is not understood. But in people with the disease, a series of three DNA building blocks — represented by the letters CAG — is repeated too many times. The repeats lead to an abnormal form of Huntingtin, which poisons nerve cells in the brain. The disease is an autosomal dominant disorder, which means that a person needs only one copy of the defective gene to develop the disorder.
If symptoms strongly suggest Huntington's disease, your doctor may recommend a genetic test for the defective gene. Before having such a test, the genetic counselor will explain the benefits and drawbacks of learning test results. Counseling throughout the process is strongly encouraged.
The movement disorders associated with Huntington's disease can include both involuntary movement problems and impairments in voluntary movements, such as:
Involuntary jerking or writhing movements (chorea)
Muscle problems, such as rigidity or muscle contracture (dystonia)
Slow or abnormal eye movements
Impaired gait, posture and balance
Difficulty with speech or swallowing
Cognitive impairments often associated with Huntington's disease include:
Difficulty organizing, prioritizing or focusing on tasks
Lack of flexibility or the tendency to get stuck on a thought, behavior or action (perseveration)
Lack of impulse control that can result in outbursts, acting without thinking and sexual promiscuity
Lack of awareness of one's own behaviors and abilities
Slowness in processing thoughts or ''finding'' words
Difficulty in learning new information
The most common psychiatric disorder associated with Huntington's disease is depression. This isn't simply a reaction to receiving a diagnosis of Huntington's disease. Instead, depression appears to occur because of injury to the brain and subsequent changes in brain function. Signs and symptoms may include:
Feelings of irritability, sadness or apathy
Fatigue and loss of energy
Frequent thoughts of death, dying or suicide
Life can be fulfilling before, during, and after Huntington's diagnosis. If you or a loved one is experiencing symptoms, consider reaching out to a genetic counselor about further steps.