An important point in pathology research using iPSCs is the nature of the control group. For genetic disorders, a control group can be created by conducting gene correction of the mutant allele in patient iPSCs. Comparisons between various groups of iPSCs (healthy, patient, and gene-corrected patient iPSCs) can be conducted to validate the results of drug screening119. iPSCs also make invaluable models in the case of sporadic diseases. In these cases, because no causal mutation is known, the nature of a control group is difficult to establish, but disease-relevant single-nucleotide polymorphisms (SNPs) can be considered instead65. As described in the “Perspective” section below, for future drug screening, sporadic disease iPSCs should allow for investigation of whether the disease is caused by genetic factors such as SNPs, somatic mutation/mosaicism, or epigenetic factors. These developments could further open the door to personalized drug screening using iPSCs135.
