Although FXS has not been associated with major depression, de novo variations in SCZ have been shown to preferentially affect FMRP targets and FMRP levels have been correlated with SCZ severity (Kovács et al., 2013; Fromer et al., 2014; Purcell et al., 2014), suggesting a potential mechanistic overlap. This evidence concerns the gene FMR1 and major depressive disorder.