In addition to the several ‘synaptic’ ASD candidate genes identified in the last few years, including NLGN3, NLGN4, SHANK2/3 and IL1RAPL1 coding for postsynaptic proteins, as well as NRXN1 and its homolog CNTNAP2 and RIMS3/NIM3, coding for presynaptic proteins, we have recently reported that nonsense and missense mutations in SYN1 (p.Q555X; p.A51G, p.A550 T and p.T567A) are associated with epilepsy and/or ASD (24,53), adding another presynaptic candidate gene as a common basis for these related diseases. The gene discussed is SHANK2; the disease is epilepsy.