Schizophrenia: a review of genetic studies.

Despite the complexities of schizophrenia, notable progress has been achieved in its diagnosis and treatment over the last 25 years. In this article we review the genetic research that provides the foundation for continued advances. One of the bases of our current understanding involves the observation that schizophrenia often runs in families. The development and utilization of stringent, reliable diagnostic criteria, together with the advent of modern family, twin, and adoption paradigms, demonstrate the importance of genetic factors in understanding the familial basis of the disorder. Refinements in diagnostic criteria have also enabled advances in understanding the likely mode--or modes--of genetic transmission of both schizophrenia and related disorders. After reviewing representative studies in these areas, we examine genetic linkage studies and our progress toward identifying the genes that cause schizophrenia. Although consistent results have been difficult to obtain and much work remains to be done, evidence for areas of vulnerability has been converging at particular chromosomal sites (e.g., 6p, 8p, and 22q), allowing for cautious optimism. Finally, we discuss challenges and prospects for the new millennium, including the clinical and ethical implications of genetic investigations.