background Genetic factors play an important role in the complex disorder schizophrenia.
Results of genetic research into schizophrenia are eagerly awaited.
aim To review the methods and results of genetic research into schizophrenia.
method Medline was used to systematically review the literature (1966-2003), using as key words 'schizophrenia', 'genetics', 'endomorphotypes', 'association', 'linkage', 'micro-array' and the names of the candidate-genes, and by searching the references of the articles thus found.
results Linkage studies have revealed at least ten chromosomal locations with candidate genes that are associated with schizophrenia or with its endophenotypes. The results are contradictory and some are probably based on studies with insufficient statistical power. Vulnerability to schizophrenia probably develops as a result of the interaction between candidate genes and the environment. conclusion Although the large amount of research into the genetic causes of schizophrenia has not yet produced unequivocal evidence, the outcome shows clearly that vulnerability to the disease has a genetic cause. The candidate genes that have been identified should help us to unravel the pathogenesis of schizophrenia. Research into genetic vulnerability factors will probably be more fruitful if endophenotypes are investigated separately and if the influence of environmental factors is taken into account.