title: No evidence for excess runs of homozygosity in bipolar disorder.
abstract: BACKGROUND
  Recent studies have reported large common regions of homozygosity (ROHs) that are the result of autozygosity, that is, the cooccurrence within individuals of long haplotypes that have a high frequency in the population. A recent study reports that such regions are found more commonly in individuals with schizophrenia compared with controls, and identified nine 'risk ROHs' that were individually more common in cases. Of these, four contained or neighboured genes associated with schizophrenia (NOS1AP/UHMK1, ATF2, NSF and PIK3C3).
  
  
  METHODS
  We have applied the same methodology to a UK sample of 506 cases with bipolar disorder and 510 controls.
  
  
  RESULTS
  There was no overall excess of common ROHs among bipolar individuals. With one exception, the haplotypes accounting for the ROHs appeared to be distributed according to the Hardy-Weinberg equilibrium. One ROH was individually more common among cases (uncorrected P = 0.0003). This ROH spanned the chromosome 2p23.3 gene ITSN2 (the gene for intersectin 2 isoform 2). However, inspection of the homozygous haplotypes and haplotype-based tests for association failed to provide a clearer understanding of why this ROH was occurring more commonly.
  
  
  CONCLUSIONS
  Overall, we conclude that, in contrast with schizophrenia, common ROHs are rarely associated with susceptibility to bipolar disorder. This supports the idea that predominantly different genes are increasing susceptibility to schizophrenia and bipolar affective disorders.
authors.affiliation: Centre for Psychiatry, University College London, UK.
authors.forename: Anna E
authors.initials: AE
authors.lastname: Vine
authors.forename: Andrew
authors.initials: A
authors.lastname: McQuillin
authors.forename: Nicholas J
authors.initials: NJ
authors.lastname: Bass
authors.forename: Ana
authors.initials: A
authors.lastname: Pereira
authors.forename: Radhika
authors.initials: R
authors.lastname: Kandaswamy
authors.forename: Michele
authors.initials: M
authors.lastname: Robinson
authors.forename: Jacob
authors.initials: J
authors.lastname: Lawrence
authors.forename: Adebayo
authors.initials: A
authors.lastname: Anjorin
authors.forename: Pamela
authors.initials: P
authors.lastname: Sklar
authors.forename: Hugh M D
authors.initials: HM
authors.lastname: Gurling
authors.forename: David
authors.initials: D
authors.lastname: Curtis
mesh_terms: D001714:Bipolar Disorder / Q000235:genetics*; D016022:Case-Control Studies; D006239:Haplotypes; D006579:Heterozygote; D006720:Homozygote; D006801:Humans