A novel mouse model expressing the full-length human HTT gene with expanded CAG repeats has been developed. This model accurately replicates the progressive and agedependent phenotypes of HD, making it a valuable tool for studying disease mechanisms and testing new therapies. New HD Integrated Staging System groups individuals with HD based on their biological, clinical, and functional characteristics. It is the first staging system developed for a genetic neurological condition and aims to improve the precision of clinical trials and patient care. 281