title: Developments in schizophrenia genetics: from linkage to microchips, deletions and duplications.
abstract: BACKGROUND
  There is strong evidence for significant contributions of genetic factors to the risk of schizophrenia. In the past 10 years, studies employing linkage and association approaches have identified multiple putative schizophrenia risk genes. For most of these, the evidence for association with schizophrenia remains weak and attempts of replication not always successful nor easy to interpret.
  
  
  OBJECTIVE
  To give an overview of new developments in genetic research of schizophrenia.
  
  
  METHODS
  The present literature on schizophrenia genetics was reviewed with special emphasis on new developments such as genome-wide association studies (GWAS), associations of copy number variations (CNVs) with schizophrenia and the role of endophenotypes in genetic research.
  
  
  RESULTS
  The first GWAS of schizophrenia have identified new putative candidate risk genes and opened avenues for investigating how multiple genes may act in functional biological pathways forming the genetic basis of schizophrenia and other complex diseases. There is growing evidence that rare de novo CNVs as well as some inherited CNVs contribute to the susceptibility to several neuropsychiatric disorders including schizophrenia. Schizophrenia endophenotypes, which possibly better represent biological phenomena than the complex clinical phenotype, are turning out to be helpful for investigating neurobiological pathways of putative risk genes.
  
  
  CONCLUSIONS
  Recent studies suggest that individual common gene variants make relatively small contributions to risk of schizophrenia but some rare CNVs may be associated with much higher risk when present. Future studies employing new technologies for identifying common and rare risk markers are likely to deepen our understanding of the genetic architecture of schizophrenia.
authors.affiliation: Landspitalinn-National University Hospital, Division of Psychiatry, Hringbraut, 101, Reykjavik, Iceland. hmagnus@landspitali.is
authors.forename: H Magnus
authors.initials: HM
authors.lastname: Haraldsson
authors.forename: Ulrich
authors.initials: U
authors.lastname: Ettinger
authors.forename: Engilbert
authors.initials: E
authors.lastname: Sigurdsson
mesh_terms: D002872:Chromosome Deletion; D058674:Chromosome Duplication / Q000235:genetics*; D056915:DNA Copy Number Variations / Q000235:genetics; D058068:Endophenotypes; D008040:Genetic Linkage; D005819:Genetic Markers / Q000235:genetics; D020022:Genetic Predisposition to Disease / Q000235:genetics; D055106:Genome-Wide Association Study; D005838:Genotype; D006801:Humans; D020411:Oligonucleotide Array Sequence Analysis; D012559:Schizophrenia / Q000175:diagnosis / Q000235:genetics*; D012565:Schizophrenic Psychology
chemical_list: D005819:Genetic Markers