Furthermore, Fmr1 knockout mice display structural deficits in dendritic spines [31,32] as well as abnormal glutamatergic [33,34,35] and GABAergic [36,37,38] neurotransmission, indicating that both excitatory and inhibitory defects contribute to circuit dysfunctions in FXS. The gene discussed is FMR1; the disease is fragile X syndrome.