FMR1 and fragile X syndrome: The mouse models for FXS, including an additional Fmr1-KO mouse line [61], a conditional knockout model (cKO) [61, 62], a point-mutant of FMRP RNA binding domain mouse model [63] and a conditional restoration (cON) line [61, 64], have been useful in studying the roles of FMRP in neurodevelopment and developing therapeutic targets.