title: Stochastic model search with binary outcomes for genome-wide association studies.
abstract: OBJECTIVE
  The spread of case-control genome-wide association studies (GWASs) has stimulated the development of new variable selection methods and predictive models. We introduce a novel Bayesian model search algorithm, Binary Outcome Stochastic Search (BOSS), which addresses the model selection problem when the number of predictors far exceeds the number of binary responses.
  
  
  METHODS
  Our method is based on a latent variable model that links the observed outcomes to the underlying genetic variables. A Markov Chain Monte Carlo approach is used for model search and to evaluate the posterior probability of each predictor.
  
  
  RESULTS
  BOSS is compared with three established methods (stepwise regression, logistic lasso, and elastic net) in a simulated benchmark. Two real case studies are also investigated: a GWAS on the genetic bases of longevity, and the type 2 diabetes study from the Wellcome Trust Case Control Consortium. Simulations show that BOSS achieves higher precisions than the reference methods while preserving good recall rates. In both experimental studies, BOSS successfully detects genetic polymorphisms previously reported to be associated with the analyzed phenotypes.
  
  
  CONCLUSIONS
  BOSS outperforms the other methods in terms of F-measure on simulated data. In the two real studies, BOSS successfully detects biologically relevant features, some of which are missed by univariate analysis and the three reference techniques.
  
  
  CONCLUSIONS
  The proposed algorithm is an advance in the methodology for model selection with a large number of features. Our simulated and experimental results showed that BOSS proves effective in detecting relevant markers while providing a parsimonious model.
authors.affiliation: Department of Industrial and Information Engineering, University of Pavia, Pavia, Italy. alberto.russu@yahoo.it
authors.forename: Alberto
authors.initials: A
authors.lastname: Russu
authors.forename: Alberto
authors.initials: A
authors.lastname: Malovini
authors.forename: Annibale A
authors.initials: AA
authors.lastname: Puca
authors.forename: Riccardo
authors.initials: R
authors.lastname: Bellazzi
mesh_terms: D000465:Algorithms; D001499:Bayes Theorem; D002874:Chromosome Mapping; D055106:Genome-Wide Association Study; D006801:Humans; D008390:Markov Chains; D015233:Models, Statistical; D009010:Monte Carlo Method; D012044:Regression Analysis; D012984:Software