At the molecular level, WS is genetically heterogeneous, with six genes known to be involved: PAX3 (encoding the paired box 3 transcription factor), EDN3 (endothelin-3), EDNRB (endothelin receptor type B), SOX10 (Sry bOX10 transcription factor), MITF (microphthalmia-associated transcription factor), and SNAI2 (snail homolog 2) (for review, see [1]). The gene discussed is MITF; the disease is Werner syndrome.