This track shows the genomic locations of the probesets and probes from the Affymetrix Exon array. This array was designed to interrogate every known and putative exon in the human genome. For the design of this array, Affymetrix compiled evidence of expression from sources including well-annotated genes such as RefSeq, genomic alignments of mRNA and EST sequences, gene predictions, exon predictions, and regions that are syntenic to conserved regions in related species. Using this evidence, Affymetrix designed a probeset for each known or putative exon. While some of these regions might never be transcribed, the goal is to obtain a comprehensive measurement of transcription in the human genome. In most cases, this array contains one probeset per exon. However, whenever this design-time evidence suggested that some exon had alternative splice sites, the exon was subdivided into two or more regions, and one probeset was designed for each region (where possible). The array contains no probesets for exons smaller than 25 nucleotides.
The exon array supports both gene-level and exon-level expression measurement. When the probesets for a single gene are analyzed together, it yields results for overall gene expression. When the probeset of each exon is contrasted against other exons in the same gene, it yields results for alternative splicing.
The probes and probesets on the exon array are divided into five levels or classes, depending mostly on the degree of design-time evidence.
The data for this track were provided by Affymetrix. Further information on the Human Exon Array is available here.