This supportive genetic evidence extends to monogenic defects such as those in GPHN[13], ANK3 [14], NRXN1 or MECP2. NRXN1 encodes a presynaptic neuronal cell adhesion molecule [15], [16] and NRXN1 genetic defects robustly associate with schizophrenia and ASD [17]–[21]. The gene discussed is NRXN1; the disease is schizophrenia.