SOX10 is a transcription factor involved in development of the neural crest and of a few non-neural crest derivatives. It has been involved in human disease (Waardenburg-Hirschsprung disease; type 4 Waardenbur syndrome) in 1998. Since then, the phenotypic spectrum has been broadened several times and now goes from mild to life-threatening phenotype. In this review, we summarize the current knowledge concerning this phenotypic continuum, the molecular aspects of SOX10 mutations, the fundamental bases of its function in close link with the patients’ features and the main ideas to keep in mind when considering this gene in human diagnosis. (By Dr. Veronique Pingault, https://jmg.bmj.com/content/early/2021/10/19/jmedgenet-2021-108105 )