Are all of the content sources taken into consideration to define the probe selection regions and how many of the PSRs are only supported by a single type of content?
All annotation sources were considered. In cases where both strong support (i.e., aligned RefSeq mRNA sequences) and poor support (i.e., GENSCAN predictions) exist, both were used. Thus, a gene locus that contains a RefSeq mRNA will frequently contain probe sets representing not only the RefSeq exons, but also a number of other exons supported by other annotation sources. Slightly over half of the array is supported only by a single source and many of these are EST- or GENACAN- based annotations. See the Exon Array Design Technical Note for a more comprehensive discussion of the content on the array.