Effect of new genebuilds and genome assembly. Fraction of annotated probesets across Affymetrix chips for Ensembl release v46 (grey) and Ensembl v51 (red). For the Ensembl release v51 the Human genome had some genes removed due to wrong predictions, and a new assembly of the Mouse genome (NCBI m37, April 2007 strain C57BL/6J) resulted in a new genebuild.
Ballester et al. BMC Genomics 2010 11:294 doi:10.1186/1471-2164-11-294