While Huntington disease (HD) is a monogenic disorder that is pathologically relatively defined, neurogenetic and clinicopathological studies have shown that there is considerable heterogeneity in Parkinson disease (PD) and dystonia. Most cases of PD and dystonia represent complex diseases presumed to be caused by the interaction of genetic susceptibilities and environmental triggers. Despite these differences, there are important commonalities in disease pathogenesis and research goals. It is imperative to identify critical disease mechanisms within each disorder to develop neuroprotective therapies. Moreover, biomarkers are urgently needed to aid diagnosis, monitor disease progression, and, as new medicines are introduced, detect the patient's response to treatment. These biomarkers could be divided into trait markers that evaluate risk of disease in presymptomatic individuals, state markers assessing the presence of established (often covert or premanifest) disease, and rate markers capable of evaluating the progression of the disease. Herein, we provide the reader with an “ABC”-type progress report on HD, PD, and dystonia. We categorized recent developments according to aetiology and pathogenesis, biomarkers, and cause-directed therapy (Figure 1). Each disease section is concluded by a brief discussion that highlights specific research initiatives and translational mandates. Owing to the uniform aetiology of HD and the relatively advanced level of basic research for this disorder, we focused on clearance of mutant huntingtin (Htt) as the most logical therapeutic target, whereas both the PD and dystonia sections provide a more general overview on translational efforts and future perspectives.