SNAI2 and Waardenburg syndrome type 2: According to current research, PAX3 is related to the pathogenesis of WS1 and WS3 (19, 20), MITF and SNAI2 play a role in the pathogenesis of WS2 (21), SOX10 is related to the pathogenesis of WS2 and WS4 (22, 23), EDNRB and EDN3 are related to the pathogenesis of WS4 (24, 25).