Since FMRP itself is developmentally regulated (Hinds et al., 1993) and was found to function in neuronal migration, differentiation and dendritic spine maturation (Hinton et al., 1991; Irwin et al., 2001; Saffary and Xie, 2011; Telias et al., 2013; La Fata et al., 2014; Khalfallah et al., 2017), it seems therefore possible that the microsatellite of FMR1 might have currently unrecognized functions in the individual peculiarities characteristic to FXS. This evidence concerns the gene FMR1 and fragile X syndrome.