IL1RAPL1 and memory impairment: IL1RAPL1 encodes the X‐linked interleukin‐1 receptor accessory protein‐like 1, which is highly expressed in the brain, particularly in the hippocampus,48 and has been found to mediate the formation of excitatory synapses.55Il1rapl1 knock‐out mice show reduced cortical neuron spine density, mild memory impairments, increased locomotor activity and reduced anxiety‐like behaviours.56 Deletions and point mutations in IL1RAPL1 have been identified in individuals with mental retardation and individuals with ASD with and without mental retardation.44, 45, 46, 47, 48, 49, 50