Huntington’s disease, also known as Huntington’s chorea, is a progressive degenerative disease of the central nervous system that is caused by an inherited gene on chromosome 4. Huntington’s disease is inherited in an autosomal dominant fashion, which means that if you have one copy of the defective gene on chromosome 4, then you will have the disease. If a parent has Huntington’s disease, each of their children have a 50 percent chance of having the disease. The genetic defect is caused by an abnormally large number of repeats of a specific sequence, CAG, in the DNA. Through the generations, the number of repeats can actually get larger, resulting in younger and younger ages of onset of Huntington’s disease.
Most cases of Huntington’s disease are considered adult-onset, with the onset of symptoms between 30 and 50, but in rare cases, symptoms may appear during the early 20’s. There is no cure for Huntington’s disease; the defective gene is present in all of the cells of a person’s body. In families with Huntington’s disease, genetic testing can determine your likelihood of developing the disease and passing the gene on to children.
Huntington’s disease causes problems with motor skills and cognition. The symptoms of Huntington’s disease can appear in a different order in different people with the disease, but the symptoms always worsen over time. The involuntary movements associated with Huntington’s disease are the reason the condition is sometimes called Huntington’s chorea. The movements are abnormal and jerky or writhing. Muscle rigidity, loss of fine motor skills, balance problems, problems with speech and swallowing, and abnormal eye movements are also characteristic of the disease.
Cognitive impairments associated with Huntington’s disease include spatial perception problems, difficulty with organization, lack of impulse control, difficulty focusing, difficulty processing thoughts, learning impairments, lack of self-awareness and lack of flexibility. Huntington’s disease can also cause clinical depression, obsessive-compulsive disorder and bipolar disorder.
In the case of juvenile Huntington’s disease, the first symptoms are usually muscle rigidity and tremor, learning problems and slow movements.
Medications such as dopamine blockers may be used to help with involuntary movements associated with Huntington’s disease. Medications such as antidepressants may also be helpful for mood disorders caused by Huntington’s disease. Physical therapy, speech therapy and occupational therapy are also helpful in treating and dealing with the symptoms of Huntington’s. After the onset of symptoms, people with Huntington’s disease live about 15 to 20 years on average.