47XXY-fibroblasts were isolated from a patient with Klinefelter syndrome (KS) and used to establish 47XXY-iPSCs using OCT4, SOX2, KLF4, and c-MYC genes as we previously described (Grad et al., 2011; Hibaoui et al., 2014). The gene discussed is KLF4; the disease is Klinefelter syndrome.