title: SNPexp - A web tool for calculating and visualizing correlation between HapMap genotypes and gene expression levels.
abstract: BACKGROUND
  Expression levels for 47294 transcripts in lymphoblastoid cell lines from all 270 HapMap phase II individuals, and genotypes (both HapMap phase II and III) of 3.96 million single nucleotide polymorphisms (SNPs) in the same individuals are publicly available. We aimed to generate a user-friendly web based tool for visualization of the correlation between SNP genotypes within a specified genomic region and a gene of interest, which is also well-known as an expression quantitative trait locus (eQTL) analysis.
  
  
  RESULTS
  SNPexp is implemented as a server-side script, and publicly available on this website: http://tinyurl.com/snpexp. Correlation between genotype and transcript expression levels are calculated by performing linear regression and the Wald test as implemented in PLINK and visualized using the UCSC Genome Browser. Validation of SNPexp using previously published eQTLs yielded comparable results.
  
  
  CONCLUSIONS
  SNPexp provides a convenient and platform-independent way to calculate and visualize the correlation between HapMap genotypes within a specified genetic region anywhere in the genome and gene expression levels. This allows for investigation of both cis and trans effects. The web interface and utilization of publicly available and widely used software resources makes it an attractive supplement to more advanced bioinformatic tools. For the advanced user the program can be used on a local computer on custom datasets.
authors.affiliation: Norwegian PSC Research Center, Clinic for Specialized Medicine and Surgery, Oslo University Hospital Rikshospitalet, Norway.
authors.forename: Kristian
authors.initials: K
authors.lastname: Holm
authors.forename: Espen
authors.initials: E
authors.lastname: Melum
authors.forename: Andre
authors.initials: A
authors.lastname: Franke
authors.forename: Tom H
authors.initials: TH
authors.lastname: Karlsen
mesh_terms: D020869:Gene Expression Profiling / Q000379:methods*; D015894:Genome, Human; D005838:Genotype; D006801:Humans; D020407:Internet; D020641:Polymorphism, Single Nucleotide; D040641:Quantitative Trait Loci; D017422:Sequence Analysis, DNA / Q000379:methods*; D012984:Software