Waardenburg Syndrome, Type 4

Clinical Characteristics
Ocular Features: 

The skin and ocular pigmentary changes and the sensorineural hearing loss in type 4 Waardenburg syndrome resembles that of other types.  Patients, however, usually lack synophrys and dystopia canthorum.

Systemic Features: 

Type 4 Waardenburg syndrome is largely similar to other types except that many patients also have Hirschsprung disease.

Genetics

Both autosomal dominant and recessive inheritance have been reported for type 4 Waardenburg syndrome.  Both heterozygous and homozygous mutations in the EDNRB (endothelin-B receptor) gene (13q22) occur in patients.  The aganglionic megacolon feature may be dose sensitive since homozygotes have been reported to have a 74% chance of developing Hirschsprung disease while only 21% of heterozygotes do so.

Types 4A (277580) and 4B (613265) are both caused by mutations in the EDNRB gene, and type 4C (613266) results from a mutation in the SOX10 gene.  Waardenburg syndrome WS2E is allelic to type 4C.  This is an example of genetic heterogeneity both within the main types and within the subtypes.

Treatment
Treatment Options: 

No ocular treatment is necessary but assistive hearing devices can be beneficial.

References
Article Title: 

Waardenburg syndrome

Read AP, Newton VE. Waardenburg syndrome. J Med Genet. 1997 Aug;34(8):656-65. Review.

PubMed ID: 
9279758

References

Pingault V, Ente D, Dastot-Le Moal F, Goossens M, Marlin S, Bondurand N. Review and update of mutations causing Waardenburg syndrome. Hum Mutat. 2010 Apr;31(4):391-406. Review.

PubMedID: 20127975

Read AP, Newton VE. Waardenburg syndrome. J Med Genet. 1997 Aug;34(8):656-65. Review.

PubMedID: 9279758

Atti?(c) T, Till M, Pelet A, Amiel J, Edery P, Boutrand L, Munnich A, Lyonnet S. Mutation of the endothelin-receptor B gene in Waardenburg-Hirschsprung disease. Hum Mol Genet. 1995 Dec;4(12):2407-9.

PubMedID: 8634719