HTT and Huntington disease: This step-by-step approach allowed the identification of a 23aa peptide (P42), lying in the N-terminus (position 480–502 aa) of normal human Htt (hHtt), able to prevent aggregation in cellulo in HeLa cells, and to retain protective properties on different phenotypes induced by the expression of the polyQ-Htt in vivo in a Drosophila model of HD (on eye degeneration, axonal trafficking and larval locomotion for instance) [8].