title: Gene expression levels assessed by oligonucleotide microarray analysis and quantitative real-time RT-PCR -- how well do they correlate?
abstract: BACKGROUND
  The use of microarray technology to assess gene expression levels is now widespread in biology. The validation of microarray results using independent mRNA quantitation techniques remains a desirable element of any microarray experiment. To facilitate the comparison of microarray expression data between laboratories it is essential that validation methodologies be critically examined. We have assessed the correlation between expression scores obtained for 48 human genes using oligonucleotide microarrays and the expression levels for the same genes measured by quantitative real-time RT-PCR (qRT-PCR).
  
  
  RESULTS
  Correlations with qRT-PCR data were obtained using microarray data that were processed using robust multi-array analysis (RMA) and the MAS 5.0 algorithm. Our results indicate that when identical transcripts are targeted by the two methods, correlations between qRT-PCR and microarray data are generally strong (r = 0.89). However, we observed poor correlations between qRT-PCR and RMA or MAS 5.0 normalized microarray data for 13% or 16% of genes, respectively.
  
  
  CONCLUSIONS
  These results highlight the complementarity of oligonucleotide microarray and qRT-PCR technologies for validation of gene expression measurements, while emphasizing the continuing requirement for caution in interpreting gene expression data.
authors.affiliation: Division of Children's Leukaemia and Cancer Research, Telethon Institute for Child Health Research and Centre for Child Health Research, The University of Western Australia, Perth, Australia. peterd@ichr.uwa.edu.au
authors.forename: Peter B
authors.initials: PB
authors.lastname: Dallas
authors.forename: Nicholas G
authors.initials: NG
authors.lastname: Gottardo
authors.forename: Martin J
authors.initials: MJ
authors.lastname: Firth
authors.forename: Alex H
authors.initials: AH
authors.lastname: Beesley
authors.forename: Katrin
authors.initials: K
authors.lastname: Hoffmann
authors.forename: Philippa A
authors.initials: PA
authors.lastname: Terry
authors.forename: Joseph R
authors.initials: JR
authors.lastname: Freitas
authors.forename: Joanne M
authors.initials: JM
authors.lastname: Boag
authors.forename: Aaron J
authors.initials: AJ
authors.lastname: Cummings
authors.forename: Ursula R
authors.initials: UR
authors.lastname: Kees
mesh_terms: D000465:Algorithms; D045744:Cell Line, Tumor; D019295:Computational Biology / Q000379:methods; D017931:DNA Primers / Q000737:chemistry; D020869:Gene Expression Profiling / Q000379:methods*; D005786:Gene Expression Regulation; D015972:Gene Expression Regulation, Neoplastic; D023281:Genomics / Q000379:methods; D006801:Humans; D015233:Models, Statistical; D020411:Oligonucleotide Array Sequence Analysis / Q000379:methods*; D009841:Oligonucleotides / Q000737:chemistry; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods*; D012984:Software
chemical_list: D017931:DNA Primers; D009841:Oligonucleotides; D012333:RNA, Messenger