title: Comparison of measures of marker informativeness for ancestry and admixture mapping.
abstract: BACKGROUND
  Admixture mapping is a powerful gene mapping approach for an admixed population formed from ancestral populations with different allele frequencies. The power of this method relies on the ability of ancestry informative markers (AIMs) to infer ancestry along the chromosomes of admixed individuals. In this study, more than one million SNPs from HapMap databases and simulated data have been interrogated in admixed populations using various measures of ancestry informativeness: Fisher Information Content (FIC), Shannon Information Content (SIC), F statistics (FST), Informativeness for Assignment Measure (In), and the Absolute Allele Frequency Differences (delta, δ). The objectives are to compare these measures of informativeness to select SNP markers for ancestry inference, and to determine the accuracy of AIM panels selected by each measure in estimating the contributions of the ancestors to the admixed population.
  
  
  RESULTS
  FST and In had the highest Spearman correlation and the best agreement as measured by Kappa statistics based on deciles. Although the different measures of marker informativeness performed comparably well, analyses based on the top 1 to 10% ranked informative markers of simulated data showed that In was better in estimating ancestry for an admixed population.
  
  
  CONCLUSIONS
  Although millions of SNPs have been identified, only a small subset needs to be genotyped in order to accurately predict ancestry with a minimal error rate in a cost-effective manner. In this article, we compared various methods for selecting ancestry informative SNPs using simulations as well as SNP genotype data from samples of admixed populations and showed that the In measure estimates ancestry proportion (in an admixed population) with lower bias and mean square error.
authors.affiliation: Cincinnati Children's Hospital Medical Center, Department of Pediatrics, University of Cincinnati, Cincinnati, OH, USA.
authors.forename: Lili
authors.initials: L
authors.lastname: Ding
authors.forename: Howard
authors.initials: H
authors.lastname: Wiener
authors.forename: Tilahun
authors.initials: T
authors.lastname: Abebe
authors.forename: Mekbib
authors.initials: M
authors.lastname: Altaye
authors.forename: Rodney C P
authors.initials: RC
authors.lastname: Go
authors.forename: Carolyn
authors.initials: C
authors.lastname: Kercsmar
authors.forename: Greg
authors.initials: G
authors.lastname: Grabowski
authors.forename: Lisa J
authors.initials: LJ
authors.lastname: Martin
authors.forename: Gurjit K
authors.initials: GK
authors.lastname: Khurana Hershey
authors.forename: Ranajit
authors.initials: R
authors.lastname: Chakorborty
authors.forename: Tesfaye M
authors.initials: TM
authors.lastname: Baye
mesh_terms: D005787:Gene Frequency; D005828:Genetics, Population; D006801:Humans; D020641:Polymorphism, Single Nucleotide