Huntington disease is a progressive brain disorder causing uncontrolled movements, emotional problems, and cognitive decline. It has two forms: adult-onset, typically appearing in the 30s or 40s, and juvenile, beginning in childhood or adolescence. Adult-onset symptoms include irritability, depression, involuntary movements, and cognitive issues, while juvenile form involves slow movements, clumsiness, and seizures. The disease is inherited in an autosomal dominant pattern, with a mutation in the HTT gene leading to an abnormally long huntingtin protein, which damages neurons. The CAG trinucleotide repeat in the HTT gene determines the severity and age of onset, with more repeats leading to earlier symptoms. Juvenile Huntington disease progresses faster and is associated with more CAG repeats. The disorder affects 3-7 per 100,000 people of European descent, less commonly in other populations. Diagnosis involves genetic testing, and management includes supportive care. Resources include GeneReviews, MedlinePlus, and patient organizations. Research focuses on understanding the disease's mechanisms and developing therapies. The condition is reviewed in various medical databases and clinical trials. References include studies on clinical features, pathogenic mechanisms, and genetic testing. The summary is based on current medical knowledge up to 2020.Huntington disease is a progressive brain disorder causing uncontrolled movements, emotional problems, and cognitive decline. It has two forms: adult-onset, typically appearing in the 30s or 40s, and juvenile, beginning in childhood or adolescence. Adult-onset symptoms include irritability, depression, involuntary movements, and cognitive issues, while juvenile form involves slow movements, clumsiness, and seizures. The disease is inherited in an autosomal dominant pattern, with a mutation in the HTT gene leading to an abnormally long huntingtin protein, which damages neurons. The CAG trinucleotide repeat in the HTT gene determines the severity and age of onset, with more repeats leading to earlier symptoms. Juvenile Huntington disease progresses faster and is associated with more CAG repeats. The disorder affects 3-7 per 100,000 people of European descent, less commonly in other populations. Diagnosis involves genetic testing, and management includes supportive care. Resources include GeneReviews, MedlinePlus, and patient organizations. Research focuses on understanding the disease's mechanisms and developing therapies. The condition is reviewed in various medical databases and clinical trials. References include studies on clinical features, pathogenic mechanisms, and genetic testing. The summary is based on current medical knowledge up to 2020.