Huntington disease: A quarter century of progress since the gene discovery.

Huntington disease (HD) is an autosomal dominant neurodegenerative disorder characterized by motor, behavioral, and cognitive manifestations. It is caused by an expansion of a trinucleotide repeat in the huntingtin gene (HTT) on chromosome 4. Although disease onset is currently clinically defined by motor signs, the presence of non-motor symptoms prior to motor diagnosis is increasingly recognized. Complex multimodal symptoms adversely affect quality of life and longevity of patients. Thoughtful interdisciplinary symptomatic care can make a major positive impact for patients and families. A variety of symptomatic treatments are currently available, and new symptomatic and potentially disease modifying therapies are being actively developed. Functional and quality of life outcome measures can be used to assess efficacy of clinical interventions. These outcomes along with clinical data and novel longitudinal biomarkers are increasingly utilized in clinical trials, particularly those testing disease-modifying therapeutics. Recent advances in novel therapeutic strategies, including targeting mutant huntingtin (HTT) and the HTT gene, promise another wave of disease-modifying trials in the near future. Better appreciation of heterogeneous clinical phenomenology and immediate tractable treatment goals coupled with advances in new therapeutics heralds a golden age of HD treatment that will positively impact quality of life and longevity of HD patients and inform advances in other inherited and neurodegenerative neurological disorders.