Waardenburg syndrome (WS) is a genetic disorder characterised by congenital hearing loss, dystopia canthorum (increased distance between the inner canthi), and abnormalities in pigmentation of the hair, skin, and eyes. There are four different types of Waardenburg Syndrome: types 1 and 2 are the most common types, whereas types 3 and 4 are relatively rare. Waardenburg syndrome type 4 (WS4; Waardenburg-Shah syndrome) is distinguished from the other types of WS by its association with Hirschsprung disease, which is a neurocristopathy clinically recognized by aganglionosis of the distal gastrointestinal tract.
WS4 is genetically heterogeneous and has several subtypes. Mutations in the EDNRB (Endothelin Receptor, Type B ) gene, located on chromosome 13q22.3, is known to cause WS4A. Other subtypes of WS4 are caused by mutations in the EDN3 gene or SOX10 gene.