Vulnerability markers in the schizophrenia spectrum: implications for phenomenology, genetics, and the identification of the schizophrenia prodrome

A continuum of symptoms between "normality" and overt psychosis has been documented in relatives of schizophrenia patients, schizotypal personality disorder (SPD), and individuals who may be in the early stages of a psychotic illness with "subsyndromal" symptoms. Questions still remain as to whether SPD is genotypically linked to schizophrenia but has genes of lesser penetrance, fewer affected genes, lack of a second hit, or perhaps protective factors. Future directions in SPD work might include the use of vulnerability markers to essentially subtype schizophrenia spectrum patients and create simpler endophenotypes to understand the phenomenologic and neurobiologic substrate. The use of vulnerability markers along with clinical symptoms may help to improve the predictive power for identifying individuals at risk for schizophrenia for early intervention. Finally, genetic studies have yet to be performed in SPD.