Advances in Medical Genetics: Huntington Disease

Medical genetics is currently enjoying a time of exploration and discovery. Huntington disease has long been of interest in adult medicine. The onset of clinical signs and symptoms is usually delayed until midadulthood. It may seem strange in this context to focus on Huntington disease, but advances in molecular genetics have brought Huntington disease into the purview of pediatrics. These advances in molecular genetics make it possible to detect Huntington disease in a preclinical stage at or even before birth. The molecular approach does not replace prior approaches to Huntington disease but is synergistic and provides a model of the new genetics. Huntington disease is synonymous with Huntington chorea. It is named after George Huntington who, like his father and grandfather before him, studied the disease in families on Long Island, NY. Huntington disease is a more common hereditary disorder than phenylketonuria, which occurs in one of about 10,000 newborns in the United States. By contrast, about one in 2,000 persons is at risk for Huntington disease. Although most cases start clinically in midadulthood, usually between 35 and 42 years of age, there is great variability in age of onset. About 3% of cases are diagnosed as juvenile Huntington disease before the age of 15 years. Late onset is well known after 50 years of age.