ABSTRACT
INTRODUCTION The field of genetics represents one of the most promising approaches to understanding the mechanisms underlying disease and behavior. Over the last several decades, we have moved from thinking of genetic disorders as rare conditions that dramatically affect a small fraction of the population to the understanding that genes influence most aspects of a person’s life and death. Well-evidenced examples of this influence include genetic associations with personality traits, cognitive style, temperament, intellect, and of course serious mental illnesses. Our knowledge of the genetic basis for major depressive disorder (MDD) and most other mental illnesses has progressed significantly but remains poorly understood because, in part, of a number of complicating factors relevant to the field of psychiatric genetics.
