Pharmacological blockade of mGlu5 receptors with selective NAMs, such as MPEP and CTEP, has been shown to correct several pathological phenotypes in mouse models of monogenic autism, such as Fmr1 knockout mice (Michalon et al., 2012; Gandhi et al., 2014), BTBR T+tf/J mice (Silverman et al., 2010; Seese et al., 2014; Yang et al., 2015), mice exposed prenatally to valproic acid (Mehta et al., 2011), mutant mice modeling human chromosome 16p11.2 microdeletion (Tian et al., 2015), and MecP2 knockout mice modeling Rett syndrome (Tao et al., 2016). Here, FMR1 is linked to atypical Rett syndrome.