title: [Genetics and psychiatric disorders: heritability and the search for genes].
abstract: BACKGROUND
  Much of the research is focused on the role that genetic factors play in the development of psychiatric disorders during childhood and adolescence.
  
  
  OBJECTIVE
  To present an overview of the heritability of these disorders and to describe the current state of the search for specific genetic variants.
  
  
  METHODS
  The results of (mainly) Dutch studies in this area are summarised.
  
  
  RESULTS
  It is estimated that about 60-70% of externalising symptoms and about 40-50% of internalising symptoms are heritable. No genes have yet been identified which influence psychiatric disorders in children. It is clear, however, that even in children, psychiatric symptoms are polygenic, i.e. influenced by many genetic variants, each having a small effect.
  
  
  CONCLUSIONS
  Research on the role of genetic factors is advancing rapidly even in child psychiatry. When sample sizes are enlarged, it should be possible to identify genetic variants.
authors.forename: C M
authors.initials: CM
authors.lastname: Middeldorp
mesh_terms: D000293:Adolescent; D000296:Adolescent Psychiatry; D002648:Child; D002665:Child Psychiatry; D002675:Child, Preschool; D014644:Genetic Variation; D006801:Humans; D065886:Neurodevelopmental Disorders / Q000175:diagnosis / Q000235:genetics*