• To evaluate whether probands from a clinical sample diagnosed as having DSM-III schizotypal and/or paranoid personality disorder have a familial relationship to the schizophrenia-related disorders, the morbid risk for schizophrenia-related disorders and other psychiatric disorders were evaluated in the first-degree relatives of patients with schizotypal and/or paranoid personality disorder and compared with the corresponding risk for these disorders in the first-degree relatives of patients with other non-schizophrenia-related personality disorders. The morbid risk for all schizophrenia-related disorders, and specifically for schizophrenia-related personality disorders, was significantly greater among the relatives of the probands with schizotypal and/or paranoid personality disorder than among the relatives of probands with other personality disorder. The morbid risk for other psychiatric disorders did not differ significantly between the first-degree relatives of the schizotypal/paranoid personality disorder and the other personality disorder control proband samples. These results suggest a specific familial association between schizophrenia-related disorders, particularly schizophrenia-related personality disorders, and clinically diagnosed schizotypal patients.
Siever LJ, Silverman JM, Horvath TB, Klar H, Coccaro E, Keefe RSE, Pinkham L, Rinaldi P, Mohs RC, Davis KL. Increased Morbid Risk for Schizophrenia Related Disorders in Relatives of Schizotypal Personality Disordered Patients. Arch Gen Psychiatry. 1990;47(7):634-640. doi:10.1001/archpsyc.1990.01810190034005