Waardenburg syndrome is a genetic disorder associated with hearing loss and changes in skin and hair pigmentation. The syndrome is named for Dutch ophthalmologist Petrus Johannes Waardenburg who first described it.
Pigmentation changes may include irises of varying color (heterochromia iridis), or a patch of white or grey hair. Hearing loss may be absent, moderate, or profound.
Types of Waardenburg syndrome
There are several subtypes of the syndrome, traceable to different genetic variations. Dystopia canthorum , a widened bridge of the nose because of lateral displacement of the inner canthus of each eye, is associated with type I.
- Type I: associated with mutations in the paired box 3 (PAX3) gene.
- Type IIa: associated with mutations in the microphthalmia-associated transcription factor (MITF) gene
- Type IIb: associated with a locus designated WS2B
- Type IIc: associated with a locus designated WS2C
- Type III: associated with mutations in the paired box gene 3 (PAX3) gene
- Type IV: Waardenberg-Hirschsprung disease, or Waardenburg-Shah syndrome, is associated with mutations in the endothelin-B receptor gene (EDNRB), the gene for its ligand, endothelin-3 (EDN3), or in the SRY-related HMG-box gene 10 (SOX10) gene. This subtype may include neurologic manifestations.
This condition is usually inherited in an autosomal dominant pattern, which means one copy of the altered gene is sufficient to cause the disorder. In most cases, an affected person has one parent with the condition. A small percentage of cases result from new mutations in the gene; these cases occur in people with no history of the disorder in their family.
Some cases of type II and type IV Waardenburg syndrome appear to have an autosomal recessive pattern of inheritance, which means two copies of the gene must be altered for a person to be affected by the disorder. Most often, the parents of a child with an autosomal recessive disorder are not affected but are carriers of one copy of the altered gene.
This article incorporates public domain text from The U.S. National Library of Medicine