Abnormal-pursuit eye movements in schizophrenia. Evidence for a genetic indicator.

Disordered smooth-pursuit eye movements occur in a high percentage of schizophrenic patients and their first-degree relatives. A Test of the hypothesis that these disorders represent a genetic indicator of schizophrenia was undertaken by testing pursuit eye movements in a sample of monozygotic and dizygotic twins discordant for clinical schizophrenia. Deviant eye tracking is significantly concordant within monozygotic twin pairs, and less so with dizygotic twin pairs discordant for schizophrenia. A genetic interpretation is consistent with these results.