Huntington disease (HD) is a progressive degenerative brain disorder that slowly diminishes a person's ability to walk, talk, think and reason. It is named after Dr. George Huntington, a physician who first published a description of the disease in 1872. The symptoms of Huntington disease are caused by a loss of cells in the basal ganglia of the brain. The resulting damage causes changes in thinking, judgment, memory, emotional control and movement. People with Huntington disease can usually maintain their independence for several years after the initial diagnosis. Eventually, however, they are unable to care for themselves. Death in Huntington patients often results from complications such as choking, heart failure, or infection.

HD usually begins between the ages of 30 and 45, although it has been found in children as young as two years of age. Children who develop a juvenile form of Huntington disease rarely live to adulthood. HD affects males and females equally and it affects all ethnic and racial groups.

HD is hereditary. It is passed from one generation to the next through a mutated gene. Each child of a person with HD has a 50% chance of inheriting the gene. Everyone who carries the gene will develop HD, unless they die of other causes before symptoms develop. Those who do not inherit the mutated gene will not develop HD, nor will their children. A genetic test is available that can accurately determine if a person carries the HD gene.