Surveying the landscape of Huntington's disease mechanisms, measurements, and medicines.

Though 20 years have now passed since the cloning of the huntingtin gene (HTT), there remains no treatment for Huntington's Disease (HD) that alters the course of disease or lifespan of patients. The reasons for this are manifold, and likely have to do with the diverse cellular pathways disrupted by mutant HTT (mHTT) protein expression. Furthermore, the evaluation of efficacy using a putative intervention is complex, largely due to the slow course of disease and variability in the classic techniques for evaluating patient symptoms and quality of life, which make the patient populations and duration of trials particularly imposing. However, there are signs for hope both in the clinic and at the bench. This review serves three purposes. It discusses the known cellular pathologies in HD, the current and upcoming methods for clinical evaluation of disease progress, and the tested and untested interventions proposed to counter the progression in animal models and patients. With the vast knowledge of pathology accumulated over two decades of modeling HD in animals and following it in patients, as well as the advances in intervention techniques both pharmaceutical and genetic, there is reason for optimism in the field. Such optimism can only be tempered by the lack of success in the clinic to this point, though patients, scientists, and clinicians all remain enthusiastic about each new trial, and progress can only continue until an effective treatment is found.