Genetic comparison between human embryonic stem cells and induced pluripotent stem cells has been hampered by genetic variation. To solve this problem, we have developed an isogenic system that allows direct comparison of induced pluripotent stem cells (hiPSCs) to their genetically matched human embryonic stem cells (hESCs). We show that hiPSCs have a highly similar transcriptome to hESCs. Global transcriptional profiling identified 102-154 genes (>2 fold) that showed a difference between isogenic hiPSCs and hESCs. A stringent analysis identified NNAT as a key imprinted gene that was dysregulated in hiPSCs. Furthermore, a disproportionate number of X-chromosome localized genes were over-expressed in female hiPSCs. Our results indicate that despite a remarkably close transcriptome to hESCs, isogenic hiPSCs have alterations in imprinting and regulation of X-chromosome genes. © 2011 Teichroeb et al.