Abstract: Provided herein are methods for diagnosing a psychotic disorder, such as schizophrenia, schizoaffective disorder or psychosis, predicated on a determination of a methylation phenotype of the subject based in part on the identity of a specific polymorphism in the MTHFR gene and the analysis of a suite of biomarkers and other functional measures and indices. Also provided herein are methods for predicting prognosis and functional outcomes for subjects having a psychotic disorder, and for treating subjects having a psychotic disorder.

Abstract: Embodiments of the present invention provide methods for diagnosing schizophrenia, schizo-affective disorder and/or psychosis in an individual or predicting risk of the individual developing schizophrenia, schizo-affective disorder or psychosis, by determining values for one or more markers in each of five domains, namely a neurotransmitter domain, an oxidative stress domain, a nutrition-biochemistry domain, a visual processing domain and an auditory processing domain.