HTT and Huntington disease: First described in 1872 by George Huntington as a hereditary movement disorder, with a spectrum of choreiform movements, rigidity, cognitive impairments, and behavioral disturbances in families from Long Island (New York, NY, USA) [3,4], the cause of HD was only resolved in 1993, when The Huntington’s Disease Collaborative Research Group identified the expansion of cytosine–adenine–guanine (CAG) trinucleotide (>36 CAG repeats) in the first exon of the HTT gene (locus 4p16.3) as HD’s cause [5].