Genetic Study of Schizophrenia

* INCLUSION/EXCLUSION CRITERIA: Inclusion criteria for Siblings (probands and unaffected siblings): * Probands must have a DSM IV-R diagnosis of schizophrenia,schizoaffective disorder, psychosis N.O.S. or schizophreniform disorder. * Probands and Siblings must be between the ages of 18 and 55 * Probands and Siblings must be free of major medical illnesses, but may have controlled hypertension, thyroid disease, or diabetes. * Probands and Siblings must have the cognitive ability to consent for themselves. Those who are judged to have the cognitive ability to consent for themselves at the time of participation, but do not have the legal capacity to consent for themselves may participate if the legal guardian /Legal authorized representative (LAR) provides consent by signing the informed consent form. * Fluency in English is required. Exclusion Criteria for Siblings (probands and unaffected siblings): * Seizure disorder, mental retardation, organic brain damage or other neurological disease. * History of any (excepting nicotine-related) DSM5-defined moderate to severe substance use disorder (or DSM-IV-defined substance dependence). * Cumulative lifetime history of any (excepting nicotine-related) DSM5-defined mild substance use disorder (or any DSM-IV-defined substance abuse), either in excess of 5 years total or not in remission for at least 6 months. * Head trauma with loss of consciousness over 5 minutes from all but genetic sampling. * Chemotherapy. * NIMH employees/staf…