With an advance of technology and an increase in sample size, many genetic variants have been identified as risk factors for mental disorders including schizophrenia, autism spectrum disorder, and bipolar disorder. These genetic findings reveal the following: 1) mental disorders show substantial genetic heterogeneity, 2) genetic variants are often associated with risk for multiple mental disorders, 3) importance of rare variants of recent origin, and 4) implications of somatic mutations of neurons in mental disorders. These genetic findings also influence clinical and basic research on mental disorders. In this article, we describe CNV-based future studies including genome cohort study, model animal study, and induced pluripotent stem cell study.