Cultured primary skin fibroblasts from three healthy control and seven PBD-ZSD patient donors with mutations in the PEX1, PEX10, PEX12, or PEX26 genes were transduced with retroviruses expressing the human OCT4, SOX2, KLF4, and c-MYC reprogramming factors (Table 1). Here, KLF4 is linked to peroxisome biogenesis disorder.