In Down syndrome, miR-155 is upregulated, leading to synaptic dysfunction through downregulation of sorting nexin 27 (SNX27) (Lu et al., 2013; Wang et al., 2013a), although miR-155 can also suppress NMII activation (Weber et al., 2014), highlighting that miRNAs often regulate multiple targets that could function in disease pathology. This evidence concerns the gene SNX27 and Down syndrome.