To investigate the molecular mechanism underlying these symptoms, two iPS cell lines derived from two HGPS patients (HGPS1 and HGPS2) and two healthy patients (WT1 and WT2) were differentiated into melanocytes using a protocol of differentiation based on the ones described by Allouche et al. 26, Gledhill et al. 27 and Mica et al. 28 (Fig. 1B). This evidence concerns the gene WT1 and Hutchinson-Gilford progeria syndrome.