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Genetic and Rare Diseases Information Center (GARD)

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Waardenburg syndrome type 1

Other Names for this Disease
  • Waardenburg's syndrome type 1
  • WS1
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Your Question

I have Waardenburg syndrome type 1. I have read that this condition is caused by mutations in the PAX3 gene on chromosome 2q35. What causes these mutations? Is it due to consanguinity?

Our Answer

We have identified the following information that we hope you find helpful. If you still have questions, please contact us.

What causes Waardenburg syndrome type 1?

Waardenburg syndrome type 1 is caused by mutations in the PAX3 gene. Researchers believe that mutations in the PAX3 gene destroy the ability of the PAX3 protein to bind to DNA and regulate the activity of other genes. As a result, pigment cells (melanocytes) do not develop in certain areas of the skin, hair, eyes, and inner ear, which leads to the hearing loss and patchy loss of pigmentation that are characteristic features of Waardenburg syndrome. In addition, these mutations disrupt the development of certain craniofacial bones, causing the widely spaced eyes that are unique to Waardenburg syndrome type 1.[1]  
Last updated: 10/20/2011

What types of mutations occur in the PAX3 gene?

Several PAX3 gene mutations have been identified in people with Waardenburg syndrome types 1 and 3. Some of these mutations change one of the chemical building blocks (amino acids) used to make the PAX3 protein. Other mutations lead to an abnormally small version of the PAX3 protein.[1] 
Last updated: 10/20/2011

How do the mutations in the PAX3 gene occur?

The PAX3 mutations responsible for Waardenburg syndrome type 1 are usually inherited in an autosomal dominant pattern, which means one copy of the altered gene in each cell 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 and the cause is unknown.[2]

Additional details regarding the inheritance of PAX3 mutations can be accessed through the GeneReviews web site.

Last updated: 10/20/2011

Is Waardenburg syndrome type 1 caused by consanguinity?

No. Waardenburg syndrome type 1 is an autosomal dominant condition. Consanguinity refers to the genetic relatedness between individuals descended from at least one common ancestor. This phenomenon is more commonly associated with autosomal recessive conditions, which require two copies of a gene mutation in a particular gene in order to express observable symptoms.

Additional information about consanguinity and genetic disorders can be accessed by clicking here.
Last updated: 10/20/2011