Abstract: Methods and kits for diagnosing a psychiatric disorder such as schizophrenia, schizo-affective disorder, bipolar disorder or Tourette syndrome, or a predisposition thereto, in a subject, are disclosed. The methods and kits are based on the detection of the presence of SNP rs1156026, and/or of deletions located in introns of the DNAJC15 gene, in a biological sample from the subject.

Abstract: The present invention relates to methods for identifying the susceptibility or predisposition of an individual to schizophrenia SZ) or to clusters of symptoms associated thereof. Particularly, the tests can be performed before or after the disorders appear. More particularly, the present invention relates to the determination of epistatic effect of at least two genotype related loci. In addition, the invention provides tests for the classification of different subtypes predicting severity of illness of patients affected by or predisposed to SZ or associated clusters of symptoms.