This review will focus on two genetic etiologies of autism spectrum disorders, SHANK3 (encoding the SH3 and multiple ankyrin repeat domains protein) and SYNGAP1 (Synaptic Ras-GTPase activating protein)-related disorders, to highlight how disruption of synaptogenesis in AMPAr-mediated neurotransmission occurs in the pathogenesis of autism in these prototypical neurodevelopmental disorders. The gene discussed is SYNGAP1; the disease is autism.