HTT and Huntington disease: In Huntington’s disease, structural and functional cerebral vascular abnormalities have been shown (Vis et al., 1998; Lin et al., 2013; Rahman et al., 2013; Hua et al., 2014; Drouin-Ouellet et al., 2015; Hsiao et al., 2015; St-Amour et al., 2015) and aggregation of mutant Huntingtin is present in the neurovascular unit (Drouin-Ouellet et al., 2015), which may affect the ability of the vascular system to respond to the demands of acute exercise.