We focused on immediate early genes and markers of plasticity (C-fos, Arc/Arg3.1, Bdnf), genes of the oxytocin/vasopressin system (Oxt, Avp, Oxtr, Avpr1a, Avpr1b) because of their key role in social behavior and evidences of altered function in Oprm1−/− mice9,11, autism gene candidates (Nlgn1, Foxp1, Crh) whose expression was dysregulated in this model9 and finally Grm4, encoding mGluR4 receptors whose activation relieves autistic symptoms9. This evidence concerns the gene OPRM1 and autism.