FXS affected human embryonic stem cell (hESC) lines and induced pluripotent stem cells (iPSCs) have provided initial insights into the molecular and cellular changes induced through the loss of FMRP in human neurons (Urbach et al., 2010; Sheridan et al., 2011; Bar-Nur et al., 2012; Doers et al., 2014; Esch et al., 2014; Halevy et al., 2015; Kaufmann et al., 2015). Here, FMR1 is linked to fragile X syndrome.