While the mechanisms governing abnormal pre-synaptic development with FMR1 deletion remain to be fully elucidated, there is intriguing evidence that FMRP can regulate pre-synaptic transmitter release via direct modulation of ion channel function independent of its role in translation regulation (see Section “Ion Channel Dysregulation and Altered Intrinsic Excitability in FXS”; Ferron et al., 2014; Myrick et al., 2015). Here, FMR1 is linked to fragile X syndrome.