Interestingly, the latter category included the Alzheimer's disease (AD)-amyloid secretase pathway, pathways previously associated to neuroprotection in HD such as IGF signaling [14] and FGF signaling [42], pathways that could play a role in neurodegenerative disease pathogenesis such as EGF signaling [43], and pathways having a dual role in neurodegeneration and neuroprotection such as Toll receptor signaling [44]. This evidence concerns the gene IGF1 and Huntington disease.