Huntington Disease

Huntington disease (HD) is an inherited, neurodegenerative condition caused by a genetic abnormality in a very small region of Chromosome 4. Characterized by progressive deterioration of brain function, HD is caused by a mutation in the coding sequence of the gene which encodes for a large protein known as huntingtin. It is an autosomal dominant disorder meaning that a single copy of the mutated gene is enough to cause the illness. HD affects several brain regions leading to a range of physical, cognitive, and behavioral problems. Movement and balance are typically impaired and the patient may display a symptom known as “chorea”, a jerky, involuntary movement of the arms and legs. Cognitive impairment can lead to difficulty learning new material or challenges with memory, problem-solving, and making decisions. Psychological symptoms like depression, anxiety and impairments in social functioning may also be present. Unfortunately, with the rapid progression, HD is almost inevitably fatal within ten to thirty years of diagnosis. Currently, there is no cure for HD, but treatments are available to manage the individual symptoms. Most of therapies target the movement disorder, such as through the use of antipsychotic medications and deep brain stimulation. A variety of psychological interventions, such as talk therapy and support group can also be beneficial in helping patients handle the psychological symptoms. At present, genetic testing is the only way to definitively diagnose HD, by determining whether the person has the altered gene associated with the disease. A positive test does not guarantee that the person will develop symptoms, but they can take comfort in understanding why their loved one was affected and can then pursue preventative measures. For those already displaying HD symptoms, the test may serve a very important role in determining metabolic, pharmacological, and disease modifying therapies.