In particular, gene expression analyses of sporadic PD (Kim et al., 2007) and AD (Lukiw, 2007; Cogswell et al., 2008) revealed that miRNA deregulation is associated to neurodegeneration, and that some miRNAs repress APP expression (Long and Lahiri, 2011; Liu et al., 2012), although discordant results suggest that some experimental and technical concerns still exist (discussed in Costa et al., 2010, 2012). This evidence concerns the gene APP and Alzheimer disease.