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TAGster: Single or Multi-Population Tag SNPs Selection, Evaluation and Visualization

Developed by:

Epidemiology and Biostatistics and Computational Biology Branches

National Institute of Environmental Health
Division of Intramural Research
Epidemiology Branch
Molecular and Genetic Epidemiology Group

TAGster is a tool to select, evaluate and visualize LD tag SNPs for single or multiple populations. The input files can be a set of dumped genotype files from Seattle SNPs (Prettybase format). The output is a set of LD tag SNPs for single or multiple populations.

The TAGster also creates figures for LD structure and genotype data with many customized tracks to facilitate investigators visually checking and optimizing tag SNPs.

The TAGster uses composite linkage disequilibrium (CLD) coefficient or r2 to measure patterns of linkage disequilibrium between polymorphic sites in a genome region within each of multiple populations, and employs 3 methods to select LD tag SNPs:

  1. A greedy algorithm to select a set containing a near-minimal number of LD tag SNPs for a single or multiple populations
  2. A computation efficient exhaustive method to select minimal number of tag SNPs for a single population
  3. A two-stage optimal method to select a set of near-minimal number of tag SNPs for multiple populations



The TAGster was developed in and is maintained at the NIEHS by Zongli Xu, Norman L. Kaplan and Jack A Taylor.


Xu Z, Kaplan NL, Taylor JA. TAGster: efficient selection of LD tag SNPs in single or multiple populations. Bioinformatics. 2007 23:3254-5. Epub 2007 Sep 7.


The TAGster is written in Perl and R  programming language, It can be run on Linux, Macintosh, or Microsoft Windows operating system with R installed.


Jack Taylor, M.D., Ph.D. (Retired)
Tel 984-287-3684
Zongli Xu, Ph.D.
Tel 984-287-3730
Fax 301-480-3290
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