Six genes are involved in this syndrome [3]: PAX3 (paired box 3 transcription factor) in WS type 1 and type 3; MITF (microphthalmia-associated transcription factor) in WS type 2; EDN3 (endothelin 3) in WS type 4; EDNRB (endothelin receptor type B) in WS type 4 and type 2; SOX10 (Sry bOX10 transcription factor) in WS type 4, type 2, and in WS with neurological features (called PCWH for Peripheral demyelinating neuropathy, Central dysmyelination, Waardenburg syndrome, and Hirschsprung disease OMIM #609136); and KITLG (KIT Ligand) in WS type 2. The gene discussed is EDNRB; the disease is Hirschsprung disease.