The NO system has been implicated in the treatment,22, 46, 47, 48, 49, 50, 51, 52, 53, 54 as well as the pathobiology of depression.49, 50, 55, 56, 57 We, therefore, further investigated PSD-95, nNOS, CAPON and sGC-β1. The gene discussed is DLG4; the disease is major depressive disorder.