The literature has many examples of abnormalities in relatives of patients with schizophrenia, from simple tests of processing speed to more complex cognitive operations that mirror those found in patients, implicating a number of potential intermediate phenotypes of interest. Because many of these will turn out to be redundant, it will be important to clarify which are independent, not only for the unnecessary repetition of information that a lack of independency could represent, but most importantly for studies of risk genes. Indeed, it is expected that some risk genes will map onto some intermediate phenotypes and not others; thus, the overlap or autonomy of different intermediate phenotypes is a crucial aspect in dissecting neural mechanisms of genetic risk.
