Now that we have a foundation in basic biometric and molecular genetics we can begin to look in depth at genetic research for behavioral phenotypes. This week we will focus on schizophrenia. There are several reasons for this focus. First, genetics research has fundamentally changed the way researchers and mental health professionals think about this devastating illness; schizophrenia illustrates the successes as well as the limitations of the genetic approach to a psychiatric illness. Second, research on schizophrenia exemplifies what genetic researchers are finding with most common mental illnesses. Although, for example, the exact chromosomal locations of risk variants and the specific candidate genes implicated certainly vary from one psychiatric illness to the next, the basic features of the genetic architecture appears to be remarkably similar across multiple psychiatric illnesses, at least at this time. So an understanding of the genetics of schizophrenia will bring with it an understanding of much of psychiatric genetics. Before discussing the genetics research, however, I think it useful that we all know at least a little about what schizophrenia is. Thus the first two modules in this unit describe the clinical phenotype and some of its basic epidemiology, information that will no doubt be very familiar to those of you with a background in clinical psychology or psychiatry. Twin and adoption studies helped to establish the heritable nature of schizophrenia (Module C) and characterize the nature of environmental influence (Module D). The current frontier in genetics research on schizophrenia is to identify the specific genetic variants that underlie its heritability. Initial attempts at identifying risk alleles using the positional cloning strategy were generally unsuccessful yet provided key insights into the nature of the disorder (Module E). Very recently, important breakthroughs have been achieved through Genome Wide Association Studies (GWAS; Module F) and rare variant analysis (Module G). Although the basic foundation for this course was introduced in Units 1-4 and we strive to minimize our use of jargon, sometimes the technical term is exactly what is needed and we will continue to introduce new terms throughout the remainder of the course. So please make use of the Glossary (linked on the navigation bar). We created it in the hope it would help minimize the impact technical jargon might have on your mastering the lecture material.