FMR1 and fragile X syndrome: In the FXS mouse model (Fmr1 knockout), absence of the translational repressor FMRP results in elevated APP levels (Westmark and Malter, 2007), and normalization of elevated APP levels by App knockdown reduces MPEP-sensitive ictal-like discharges in CA3 (Westmark et al., 2016) as well as audiogenic seizures (Westmark et al., 2011).