Thus far, adult neurological and behavioural phenotypes have been shown to be at least partially reversible in mouse models of Rett syndrome caused by deletions in MeCP2 [43], SYNGAP1 haploinsufficiency [44], SHANK3‐induced autism [45] and CDKL5 deficiency disorder [46]. Here, SYNGAP1 is linked to atypical Rett syndrome.