Type 3 is characterized by musculoskeletal abnormalities. Waardenburg-Shah syndrome (type 4), which is associated with Hirschsprung disease, is the rarest subtype and is caused by genetic mutations in the endothelin receptor type B (<i>EDNRB</i>), endothelin-3 (<i>EDN3</i>), or sex-determining region Y (SRY) box 10 (<i>SOX10</i>) gene. This evidence concerns the gene EDNRB and Hirschsprung disease.