We report that hippocampal Cntnap4 deficiency in female mice, including mice injected with adeno‐associated virus (AAV)‐packaged Cntnap4 shRNA and heterozygous Cntnap4 knockout (Cntnap4+/−) mice, manifests as cognitive impairment and dysfunctional synaptic transmission. The gene discussed is CNTNAP4; the disease is Cognitive impairment.