Waardenburg syndrome is a genetic disorder that may be evident at birth (congenital). The range and severity of associated symptoms and findings may vary greatly from case to case. However, primary features often include distinctive facial abnormalities; unusually diminished coloration (pigmentation) of the hair, the skin, and/or the iris of both eyes (irides); and/or congenital deafness. More specifically, some affected individuals may have an unusually wide nasal bridge due to sideways (lateral) displacement of the inner angles (canthi) of the eyes (dystopia canthorum). In addition, pigmentary abnormalities may include a white lock of hair growing above the forehead (white forelock); premature graying or whitening of the hair; differences in the coloration of the two irides or in different regions of the same iris (heterochromia irides); and/or patchy, abnormally light (depigmented) regions of skin (leukoderma). Some affected individuals may also have hearing impairment due to abnormalities of the inner ear (sensorineural deafness).
Researchers have described different types of Waardenburg syndrome (WS), based upon associated symptoms and specific genetic findings. For example, Waardenburg syndrome type I (WS1) is characteristically associated with sideways displacement of the inner angles of the eyes (i.e., dystopia canthorum), yet type II (WS2) is not associated with this feature. In addition, WS1 and WS2 are known to be caused by alterations (mutations) of different genes. Another form, known as type III (WS3), has been described in which characteristic facial, eye (ocular), and hearing (auditory) abnormalities may be associated with distinctive malformations of the arms and hands (upper limbs). A fourth form, known as WS4 or Waardenburg-Hirschsprung disease, may be characterized by primary features of WS in association with Hirschsprung disease. The latter is a digestive (gastrointestinal) disorder in which there is absence of groups of specialized nerve cell bodies within a region of the smooth (involuntary) muscle wall of the large intestine.
In most cases, Waardenburg syndrome is transmitted as an autosomal dominant trait. A number of different disease genes have been identified that may cause Waardenburg syndrome in certain individuals or families (kindreds).