Mouse models of RCAN1 overexpression have shown a role of RCAN1 regulating exocytosis in chromaffin cells and in mutant huntingtin phosphorilation, suggesting a role of RCAN1 in the Alzheimer's disease neuropathology associated to DS and in Huntington's disease [8], [9], [10]. This evidence concerns the gene RCAN1 and juvenile Huntington disease.