Huntington's Disease

Huntington's Disease (HD) is an autosomal dominant genetic disorder characterized by progressive chorea, cognitive decline, and personality changes leading to dementia, with onset typically in midlife. Currently, there are no effective treatments to cure or delay the disease progression. HD is listed in the "First Batch of Rare Diseases Catalog" jointly formulated by the National Health Commission and four other departments.
The abnormal expansion of CAG triplet repeats in the first exon of the huntingtin (Htt) gene leads to mutant huntingtin protein expression, which causes neurodegeneration through various molecular mechanisms in the brain. Individuals with 36 or more CAG repeats are affected, with reduced penetrance if the repeat number is between 36 and 39. Triplet repeat numbers are unstable and can change when passed on to the next generation.