The HG-U133A array represents the vast majority of the genes featured on its predecessor, the HG-U95A Array. Similarly, a large percentage of the genes featured on the HG-U95B, HG-U95C, HG-U95D, and HG-U95E arrays are also represented on the arrays in the HG-U133 Set (HG-U133A and HG-U133B). However, due to the dynamic nature of public databases, probe sets for these sequences will not be identical and, in some cases, will be represented by a completely new probe set. Consequently, data generated with different versions of the human arrays may not always produce concordant results.