title: A double classification tree search algorithm for index SNP selection.
abstract: BACKGROUND
  In population-based studies, it is generally recognized that single nucleotide polymorphism (SNP) markers are not independent. Rather, they are carried by haplotypes, groups of SNPs that tend to be coinherited. It is thus possible to choose a much smaller number of SNPs to use as indices for identifying haplotypes or haplotype blocks in genetic association studies. We refer to these characteristic SNPs as index SNPs. In order to reduce costs and work, a minimum number of index SNPs that can distinguish all SNP and haplotype patterns should be chosen. Unfortunately, this is an NP-complete problem, requiring brute force algorithms that are not feasible for large data sets.
  
  
  RESULTS
  We have developed a double classification tree search algorithm to generate index SNPs that can distinguish all SNP and haplotype patterns. This algorithm runs very rapidly and generates very good, though not necessarily minimum, sets of index SNPs, as is to be expected for such NP-complete problems.
  
  
  CONCLUSIONS
  A new algorithm for index SNP selection has been developed. A webserver for index SNP selection is available at http://cognia.cu-genome.org/cgi-bin/genome/snpIndex.cgi/
authors.affiliation: Laboratory of Population Genetics, National Cancer Institute, NIH, Bethesda, MD 20892, USA. zhangpeis@mail.nih.gov
authors.forename: Peisen
authors.initials: P
authors.lastname: Zhang
authors.forename: Huitao
authors.initials: H
authors.lastname: Sheng
authors.forename: Ryuhei
authors.initials: R
authors.lastname: Uehara
mesh_terms: D000465:Algorithms; D019295:Computational Biology / Q000379:methods; D006239:Haplotypes / Q000235:genetics; D020641:Polymorphism, Single Nucleotide / Q000235:genetics*; D012641:Selection, Genetic; D012984:Software / Q000145:classification*; D012985:Software Design