title: [Heritability of bipolar affective disorder--family study].
abstract: OBJECTIVE
  Bipolar affective disorder is mental disorder with polygenic type of heredity. Heritability--relation between genetic and environmental variance is used to estimate the level of influence of genetic variance to phenotype variance. Study results show decreasing trend in the value of heritability of bipolar affective disorder, thus indicating that this disorder is a complex behavioral threshold characteristic. Therefore, the aim of this study was to estimate the contribution of genetic variance to phenotype variance of bipolar affective disorder, i.e. to estimate heritability of this disorder.
  
  
  METHODS
  By the use of a questionnaire, 80 patients with over crossed threshold for bipolar affective disorder were asked for functional information about the members of their families belonging to the first degree of relation (fathers, mothers and full-sibs). By using "Applet for calculating heritability for threshold traits (disease)", and regression analysis, heritability of bipolar affective disorder as well as its statistical significance, were estimated (chi2 test).
  
  
  RESULTS
  Heritability and relationship of genetic and environmental variance of bipolar affective disorder is 0.2 with statistically significant difference from zero (p < 0.001).
  
  
  CONCLUSIONS
  The estimated contribution of genetic variance to phenotype variance of bipolar affective disorder is low being 20%, while the contribution of environmental variance is 80%. This result contributes to the understanding of bipolar affective disorder as a complex behavioral threshold trait.
authors.affiliation: Institut za mentalno zdravlje, Beograd, Srbija. tanjaobr@gmail.com
authors.forename: Tanja
authors.initials: T
authors.lastname: Obradović
authors.forename: Ruzica
authors.initials: R
authors.lastname: Velicković
authors.forename: Ivana
authors.initials: I
authors.lastname: Timotijević
authors.forename: Marko
authors.initials: M
authors.lastname: Andjelković
mesh_terms: D000328:Adult; D001714:Bipolar Disorder / Q000235:genetics*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D019655:Quantitative Trait, Heritable; D011795:Surveys and Questionnaires; D055815:Young Adult