HTT and Huntington disease: Since the activity of GS1 was found reduced in neuronal diseases [13] and in the postmortem brains of patients with HD [14,15,16], we decided to investigate the contribution of GS1 to HD, using a well-established Drosophila model for HD that expresses the exon1 of the human HTT gene with 93 CAG repeats, (hereon referred to as Htt-Q93).