title: The Bayesian lasso for genome-wide association studies.
abstract: BACKGROUND
  Despite their success in identifying genes that affect complex disease or traits, current genome-wide association studies (GWASs) based on a single SNP analysis are too simple to elucidate a comprehensive picture of the genetic architecture of phenotypes. A simultaneous analysis of a large number of SNPs, although statistically challenging, especially with a small number of samples, is crucial for genetic modeling.
  
  
  METHODS
  We propose a two-stage procedure for multi-SNP modeling and analysis in GWASs, by first producing a 'preconditioned' response variable using a supervised principle component analysis and then formulating Bayesian lasso to select a subset of significant SNPs. The Bayesian lasso is implemented with a hierarchical model, in which scale mixtures of normal are used as prior distributions for the genetic effects and exponential priors are considered for their variances, and then solved by using the Markov chain Monte Carlo (MCMC) algorithm. Our approach obviates the choice of the lasso parameter by imposing a diffuse hyperprior on it and estimating it along with other parameters and is particularly powerful for selecting the most relevant SNPs for GWASs, where the number of predictors exceeds the number of observations.
  
  
  RESULTS
  The new approach was examined through a simulation study. By using the approach to analyze a real dataset from the Framingham Heart Study, we detected several significant genes that are associated with body mass index (BMI). Our findings support the previous results about BMI-related SNPs and, meanwhile, gain new insights into the genetic control of this trait.
  
  
  BACKGROUND
  The computer code for the approach developed is available at Penn State Center for Statistical Genetics web site, http://statgen.psu.edu.
authors.affiliation: Department of Statistics, Pennsylvania State University, State College, PA 16802, USA.
authors.forename: Jiahan
authors.initials: J
authors.lastname: Li
authors.forename: Kiranmoy
authors.initials: K
authors.lastname: Das
authors.forename: Guifang
authors.initials: G
authors.lastname: Fu
authors.forename: Runze
authors.initials: R
authors.lastname: Li
authors.forename: Rongling
authors.initials: R
authors.lastname: Wu
mesh_terms: D000465:Algorithms; D001499:Bayes Theorem; D015992:Body Mass Index; D003198:Computer Simulation; D005260:Female; D055106:Genome-Wide Association Study; D006801:Humans; D008297:Male; D008390:Markov Chains; D015233:Models, Statistical; D020641:Polymorphism, Single Nucleotide; D025341:Principal Component Analysis