SCN2A and Anxiety: Ultrasonic vocalizations• Young and adult Scn2a ± mice displayed deficits in social communicationSelf-grooming behaviour and marble burying test• Young Scn2a ± displayed stereotyped and repetitive behaviours which were not seen in adult Scn2a ± miceTail suspension test• Young Scn2a ± mice are less resigned than adult mutantsOpen-field test and elevated plus maze• Young Scn2a ± mice showed less anxiety compared to adult SCN2A ± mice