In order to determine if Necdin deficiency is responsible for the autism-related deficits in Cntnap2−/− mice, AAV-EGFP or rAAV-EF1a-Necdin-2A-EGFP (AAV-Necdin) were injected into the mPFC of WT and Cntnap2-/- mice at the age of 4 weeks and the social behaviors and grooming were measured at the age of 7 weeks (Supplementary Fig. 8a). Here, NDN is linked to autism.