The role of CAPON in binding nitric oxide synthase (Figure 1) places it at the centre of regulation of N-methyl-D-aspartate (NMDA) receptor–mediated glutamate neurotransmission, abnormalities of which have long been proposed to be involved in schizophrenia, lending credence to CAPON as a susceptibility gene for the disorder. The gene discussed is NOS1AP; the disease is schizophrenia.