The pigmentation process is modulated by various elements, including growth factors, the physiochemical environment of the HF and signalling pathways such as MAPK, stem cell factor/c-Kit, microphthalmia-associated transcription factor (MITF), endothelin (ET) 1, ET3/ETA and ETB (Shin and Lee, 2013; D’Mello et al., 2016; Chen T. et al., 2018). Here, MITF is linked to hydrops fetalis.