title: Allelic heterogeneity in genetic association meta-analysis: an application to DTNBP1 and schizophrenia.
abstract: OBJECTIVE
  Meta-analysis of genetic association studies is a useful approach when individual investigations do not yield studywise significant results but the evidence across studies is modest and homogeneous. Current meta-analysis methods account for heterogeneity by down-weighting studies as a function of between-study variance. We contend that current approaches may obscure interesting phenomena in genetic association data. However, an appropriate approach to examining heterogeneity across studies is lacking.
  
  
  METHODS
  We develop a novel approach, based on the EM algorithm, to detect allelic heterogeneity, identify subpopulations and assign studies to those subpopulations. We then apply these methods to the association between DTNBP1 and schizophrenia (Scz), one of the most studied relationships in complex disease genetics. We examined 32 published and unpublished population and family-based association studies containing up to 14 SNPs spanning the DTNBP1 locus.
  
  
  RESULTS
  We explored heterogeneity in several ways including meta-regression and approaches aimed at exploring the mixture of heterogeneous studies at a particular SNP. We found significant evidence for a mixture of association distributions at multiple loci.
  
  
  CONCLUSIONS
  We propose a novel approach that is broadly applicable and may be useful in large scale genetic association meta-analyses to detect significant allelic heterogeneity.
authors.affiliation: Department of Psychiatry, Virginia Institute for Psychiatric and Behavioral Genetics, Virginia Commonwealth University, Richmond, VA 23298-0126, USA. bsmaher@vcu.edu
authors.forename: Brion S
authors.initials: BS
authors.lastname: Maher
authors.forename: Mark A
authors.initials: MA
authors.lastname: Reimers
authors.forename: Brien P
authors.initials: BP
authors.lastname: Riley
authors.forename: Kenneth S
authors.initials: KS
authors.lastname: Kendler
mesh_terms: D000465:Algorithms; D002352:Carrier Proteins / Q000235:genetics* / Q000378:metabolism; D000074765:Dysbindin; D049029:Dystrophin-Associated Proteins; D056726:Genetic Association Studies / Q000379:methods*; D018740:Genetic Heterogeneity; D020022:Genetic Predisposition to Disease; D006801:Humans; D020641:Polymorphism, Single Nucleotide; D012559:Schizophrenia / Q000235:genetics*
chemical_list: D002352:Carrier Proteins; C432416:DTNBP1 protein, human; D000074765:Dysbindin; D049029:Dystrophin-Associated Proteins