One important reason for the popularity of endophenotypes is that they are believed to improve the chances of detecting at a molecular level the genetic variants that contribute to disease susceptibility (Freimer & Sabatti, 2003, 2004). We can summarize the argument as follows: endophenotypes provide a genetically tractable target, one that lies in the gap between gene and disease process, so that by dissecting their genetic basis we would understand something about the biology of a psychiatric disease. An example will clarify the idea.
