Schizophrenia is a complex disorder that affects roughly 1% of the world’s population. The first symptoms of schizophrenia typically appear in adolescence. In a genome-wide association study of 1,735 schizophrenic patients and 3,485 healthy adults, we identified copy number variations (CNVs – segments of DNA consisting of deleted, duplicated, or rearranged genetic material) as a potential cause of the disorder. In the schizophrenia group, we located CNVs near the CACNA1B and DOC2A genes, both of which facilitate calcium signals that are important to neurotransmission in the brain. We also identified CNVs near the RET and RIT2 genes, which are known to be involved in brain development. Interestingly some of the regions associated with schizophrenia have previously been found to associate with autism and ADHD. This provides a strong indication that many psychiatric disorders stem share similar neurodevelopmental features. This paper was published in the Proceedings of the National Academy of Sciences.