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GeneChip® Rat Expression Set 230
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What is the nature of specificity of the probes included in the GeneChip Rat Expression Set 230?
The probes on the Rat 230 are designed to detect an anti-sense target prepared by the Affymetrix 3' biased assay, and these probes are annotated with the "_at" extension. The primary goal in probe selection is to select a probe set unique to single transcript or common among multiple transcripts from the same gene.

Often it is not possible to select a probe set that is unique to a single transcript because multiple transcript variants share common sequence. Such probe sets have the "_s" extension. Occasionally, it is not possible to select a unique or shared probe set. Such probe sets have the "_x" extension. For more information, please review the "_s" and "_x" probe set descriptions.

Please note: There are no "_f", "_g", "_r", "_i", or "_n" probe sets in the Rat Expression Set 230 design opposed to the RG-U34 design. This is because the non-unique probe set types were simplified and adjusted to account for improvements to the probe selection rules.