MITF is a transcription factor that contains both basic helix-loop-helix and leucine zipper structural features. Plays a critical role in the differentiation of various cell types including neural crest- derived melanocytes, mast cells, osteoclasts and optic cup-derived retinal pigment epithelium. Two isoforms are known: the M-isoform is expressed exclusively in melanocytes, while the A-isoform has a much broader range of expression. Mutations in MITF can lead to Waardenburg syndrome. Ten alternatively spliced isoforms have been described.