Previous genetic analyses of patients with schizophrenia have found no de novo mutations in ABCC9,25–31 but three rare variants in patients with schizophrenia were reported in Genovese et al.32 Although not conclusive, somatic mutations in ABCC9 might cause abnormal brain dysfunctions through potassium-dependent neural electricity, contributing to delusional disorder. Here, ABCC9 is linked to delusional disorder.