We need next to examine the genetic architecture of endophenotypes. We start by considering some of the most heavily investigated endophenotypes in schizophrenia, measures of neuropsychological dysfunction, and particularly those that reflect activity in the prefrontal and temporo-limbic systems (Cannon et al. 2000). Abnormalities of working memory, episodic learning, attention and reaction time aggregate in the families of schizophrenia patients and probably arise from a common genetic susceptibility (Cannon et al. 2000), as expected for an endophenotype of schizophrenia.
