Genomic distribution of unannotated probesets. Ternary diagram representing the mapping of unannotated probesets for the Affymetrix gene chip HG_U133_A_2, Mouse430_2 and Rat230_2. Each corner of a plot represent a different group, the Exons-UTRs group with probes mapping within exons or UTRs, the Borders group with probes mapping to boundaries of exons/introns/UTRs/intergenic regions, and the Introns-intergenic group with probes mapping to introns or intergenic regions. Probesets having less than 50% of probes mapped and with 50% of those targeting exons are coloured in blue. These blue points correspond to probesets that could putatively be "annotated" if more probes where mapped to the genome. The red dots in the middle of the blue cluster correspond to probesets mapping to non protein-coding genes (rRNA, V_segment, pseudogene).
Ballester et al. BMC Genomics 2010 11:294 doi:10.1186/1471-2164-11-294