title: Multiple testing in genome-wide association studies via hidden Markov models.
abstract: BACKGROUND
  Genome-wide association studies (GWAS) interrogate common genetic variation across the entire human genome in an unbiased manner and hold promise in identifying genetic variants with moderate or weak effect sizes. However, conventional testing procedures, which are mostly P-value based, ignore the dependency and therefore suffer from loss of efficiency. The goal of this article is to exploit the dependency information among adjacent single nucleotide polymorphisms (SNPs) to improve the screening efficiency in GWAS.
  
  
  RESULTS
  We propose to model the linear block dependency in the SNP data using hidden Markov models (HMMs). A compound decision-theoretic framework for testing HMM-dependent hypotheses is developed. We propose a powerful data-driven procedure [pooled local index of significance (PLIS)] that controls the false discovery rate (FDR) at the nominal level. PLIS is shown to be optimal in the sense that it has the smallest false negative rate (FNR) among all valid FDR procedures. By re-ranking significance for all SNPs with dependency considered, PLIS gains higher power than conventional P-value based methods. Simulation results demonstrate that PLIS dominates conventional FDR procedures in detecting disease-associated SNPs. Our method is applied to analysis of the SNP data from a GWAS of type 1 diabetes. Compared with the Benjamini-Hochberg (BH) procedure, PLIS yields more accurate results and has better reproducibility of findings.
  
  
  CONCLUSIONS
  The genomic rankings based on our procedure are substantially different from the rankings based on the P-values. By integrating information from adjacent locations, the PLIS rankings benefit from the increased signal-to-noise ratio, hence our procedure often has higher statistical power and better reproducibility. It provides a promising direction in large-scale GWAS.
  
  
  BACKGROUND
  An R package PLIS has been developed to implement the PLIS procedure. Source codes are available upon request and will be available on CRAN (http://cran.r-project.org/).
  
  
  BACKGROUND
  zhiwei@njit.edu
  
  
  BACKGROUND
  Supplementary data are available at Bioinformatics online.
authors: Department of Computer Science, New Jersey Institute of Technology, Newark, NJ 07102, USA. zhiwei@njit.edu
authors: Zhi
authors: Z
authors: Wei
authors: Wenguang
authors: W
authors: Sun
authors: Kai
authors: K
authors: Wang
authors: Hakon
authors: H
authors: Hakonarson
mesh_terms: D000818:Animals; D030541:Databases, Genetic; D016678:Genome; D055106:Genome-Wide Association Study / Q000379:methods*; D023281:Genomics / Q000379:methods; D006801:Humans; D008390:Markov Chains; D020641:Polymorphism, Single Nucleotide