It has been difficult to pinpoint the pathogenesis of FXS due to the widespread influence of Fragile X Messenger Ribonucleoprotein (FMRP; Fmrp in zebrafish) on synapse formation and function (Huber et al., 2002; Todd et al., 2003; Dictenberg et al., 2008; Doll et al., 2017). Here, FMR1 is linked to fragile X syndrome.