NRXN1 and autism: In contrast, mice null for another gene in the neurexin family, α-neurexin I (Nrxn1α), have shown heightened sociability, with significantly more time spent exploring the stranger mouse in the three-chamber social approach test and more aggression towards juvenile conspecifics,36 although another study observed unaltered sociability.37 Nrxn2α KO mice may thus model social deficits associated with autism better than Nrxn1α KO mice.