The Rho-family of small GTPases, including Rac, Rho, and Cdc42, as well as certain downstream effectors, have been demonstrated to play a pivotal role in regulating actin dynamics during dendrite and dendritic spine morphogenesis [8]–[12] and moreover, defects in Rho GTPase signaling have been implicated in various forms of mental retardation [13]. This evidence concerns the gene RHO and Intellectual disability.