Copy number variations (CNVs) are gains and losses of DMA segments in the human genome, and form genetic variations. Recent studies have shown that CNVs contribute to the phenotypic variation in humans and are associated with complex diseases, including psychiatric disorders. Emerging evidence indicates that CNVs play a role in the genetic etiology of mental retardation, autism, schizophrenia, and bipolar disorders. This review summarizes the latest findings of recent research on the role of CNVs in the pathogenesis of these four psychiatric disorders. The positive association of CNVs with psychiatric disorders has several implications: (1) at least in some patients, the genetic defects in each patient are individualized with high penetrance, which is different from the prevailing common variant hypothesis of complex psychiatric disorders; (2) the identification of pathogenic CNVs in psychiatric disorders would bring new insight into the pathogenesis of mental disorders; (3) array-based comparative genomic hybridization technology has the potential to become a useful laboratory tool in clinical practice to help in diagnosing psychiatric disorders.
