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J Med Genet 42:193-204 doi:10.1136/jmg.2005.030718
  • Review

The genetics of schizophrenia and bipolar disorder: dissecting psychosis

  1. N Craddock,
  2. M C O’Donovan,
  3. M J Owen
  1. Department of Psychological Medicine, The Henry Wellcome Building for Biomedical Research in Wales, Wales School of Medicine, Cardiff University, Heath Park, Cardiff, CF14 4XN, UK
  1. Correspondence to:
 Nick Craddock
 Department of Psychological Medicine, The Henry Wellcome Building for Biomedical Research, Academic Avenue, Wales School of Medicine, Cardiff University, Heath Park, Cardiff, CF14 4XN, UK; craddockncardiff.ac.uk
  • Received 5 January 2005
  • Accepted 5 January 2005

Abstract

Much work has been done to identify susceptibility genes in schizophrenia and bipolar disorder. Several well established linkages have emerged in schizophrenia. Strongly supported regions are 6p24–22, 1q21–22, and 13q32–34, while other promising regions include 8p21–22, 6q16–25, 22q11–12, 5q21–q33, 10p15–p11, and 1q42. Genomic regions of interest in bipolar disorder include 6q16–q22, 12q23–q24, and regions of 9p22–p21, 10q21–q22, 14q24–q32, 13q32–q34, 22q11–q22, and chromosome 18. Recently, specific genes or loci have been implicated in both disorders and, crucially, replicated. Current evidence supports NRG1, DTNBP1, DISC1, DAOA(G72), DAO, and RGS4 as schizophrenia susceptibility loci. For bipolar disorder the strongest evidence supports DAOA(G72) and BDNF. Increasing evidence suggests an overlap in genetic susceptibility across the traditional classification systems that dichotomised psychotic disorders into schizophrenia or bipolar disorder, most notably with association findings at DAOA(G72), DISC1, and NRG1. Future identification of psychosis susceptibility genes will have a major impact on our understanding of disease pathophysiology and will lead to changes in classification and the clinical practice of psychiatry.

Footnotes

  • The authors are grateful for support for their research in the genetics of schizophrenia and bipolar disorder to the UK Medical Research Council and the Wellcome Trust

  • Competing interests: none declared