Alternative mapping of probes to genes for Affymetrix chips.
BACKGROUND
Short oligonucleotide arrays have several probes measuring the expression level of each target transcript. Therefore the selection of probes is a key component for the quality of measurements. However, once probes have been selected and synthesized on an array, it is still possible to re-evaluate the results using an updated mapping of probes to genes, taking into account the latest biological knowledge available.


METHODS
We investigated how probes found on recent commercial microarrays for human genes (Affymetrix HG-U133A) were matching a recent curated collection of human transcripts: the NCBI RefSeq database. We also built mappings and used them in place of the original probe to genes associations provided by the manufacturer of the arrays.


RESULTS
In a large number of cases, 36%, the probes matching a reference sequence were consistent with the grouping of probes by the manufacturer of the chips. For the remaining cases there were discrepancies and we show how that can affect the analysis of data.


CONCLUSIONS
While the probes on Affymetrix arrays remain the same for several years, the biological knowledge concerning the genomic sequences evolves rapidly. Using up-to-date knowledge can apparently change the outcome of an analysis.
Center for Biological Sequence Analysis, Technical University of Denmark, 2800 Lyngby, Denmark. laurent@cbs.dtu.dk
Laurent
L
Gautier
Morten
M
Møller
Lennart
L
Friis-Hansen
Steen
S
Knudsen
D001483:Base Sequence / Q000235:genetics; D015342:DNA Probes / Q000235:genetics* / Q000592:standards*; D030541:Databases, Genetic; D020869:Gene Expression Profiling / Q000379:methods / Q000592:standards*; D005786:Gene Expression Regulation / Q000235:genetics; D005796:Genes / Q000235:genetics*; D006801:Humans; D020411:Oligonucleotide Array Sequence Analysis / Q000379:methods / Q000592:standards*; D012015:Reference Standards; D012984:Software
D015342:DNA Probes