The most common causes of WS4 (WS4C, OMIM 613266) and PCW/PCWH (OMIM 609136) are mutations in SOX10, which accounts for 45%–55% of cases, followed by pathogenic variants of EDN3 and EDNRB in 20%–30%, and lastly SNAI2 mutations (Puffenberger et al., 1994; Pingault et al., 1998; Bondurand et al., 2007; Chaoui et al., 2011; Zhang et al., 2012; Song et al., 2016; Li et al., 2019; Van Camp and Smith, 2019). The gene discussed is SOX10; the disease is Waardenburg-Shah syndrome.