1. Huntington's disease, or HD, is a genetic disorder that affects the brain and causes physical and mental symptoms. It is caused by a mutation in a single gene on chromosome 4. The mutation results in the production of an abnormal form of a protein called huntingtin. This protein accumulates in the brain and damages neurons, which leads to the symptoms of HD.
2. Symptoms of HD usually begin to appear between the ages of 30 and 50, but they can begin earlier or later. The most common symptom is uncontrollable movements of the body, including writhing, jerking and twitching. Other symptoms include cognitive and emotional changes, difficulty with coordination and balance, and difficulty speaking or swallowing.
3. HD is a hereditary disorder, meaning that it is passed down from parent to child through a mutated gene. If one parent has the mutated gene, there is a 50% chance that the child will also inherit it. Unfortunately, there is no cure for HD, but medications can be used to manage some of the symptoms. There is also a test available to determine whether someone has the mutated gene.