IFNG and vitiligo: Figure 1 shows the cycle of enzymatic regeneration of H4Bip during the process of melanogenesis, which can be disturbed under conditions of oxidative stress in vitiligo [15,19,20,21,22,23]. Epidermal biosynthesis of H4Bip from GTP is controlled by hormones and cytokines and may be increased by interferon gamma in vitiligo [11,15]. Being a reduced compound, H4Bip is easily oxidized by atmospheric oxygen (the so-called autoxidation) both in vitro and in vivo [24,25].