Hi Feng, probe sets labelled with "_x" cross-hybridize to multiple genes: http://www.affymetrix.com/support/help/faqs/mouse_430/faq_8.jsp Genecards gives more detail for this probe set: http://genecards.weizmann.ac.il/cgi-bin/geneannot/GA_search.pl?keyword _type=probe_set_id&array=HG-U133&target=genecards&keyword=200012_x_at How to handle such a case depends on how interested you are in that probe set; at the extremes you could ignore it, or follow up with PCR to establish which transcript you are observing. -Levi On Mon, Jul 29, 2013 at 6:06 PM, Feng Tian <fengtian@bu.edu> wrote: > Dear all, > > In the Affymetrix annotation file, I find that some probe set ID are mapped > to multiple genes separated by '///', such as 200012_x_at is mapped > to RPL21P16///RPL21P119///RPL21. How to handle this case? > > Thank you! > > Feng > > [[alternative HTML version deleted]] > > _______________________________________________ > Bioconductor mailing list > Bioconductor@r-project.org > https://stat.ethz.ch/mailman/listinfo/bioconductor > Search the archives: > http://news.gmane.org/gmane.science.biology.informatics.conductor > -- Levi Waldron Post-doctoral fellow Department of Biostatistics, Harvard School of Public Health Department of Biostatistics and Computational Biology, Dana-Farber Cancer Institute Building 1, room 412C 655 Huntington Avenue Boston, Massachusetts 02115 mobile: (617) 851-6849 fax: (617) 432-5619 http://www.hsph.harvard.edu/research/levi-waldron/ [[alternative HTML version deleted]]