It can be inherited in an autosomal dominant or autosomal recessive manner; it is possible for two parents with Waardenburg syndrome type 1 to have a child carrying both mutated copies of the PAX3 gene (25% chance) and present with Waardenburg syndrome type 3. A missense mutation has been documented to have this effect. However, it is also possible for Waardenburg syndrome type 3 to present spontaneously with just one mutated copy of PAX3. A deletion of the paired domain region of the gene has been documented to have this effect. However, no major correlation has been found between type of mutation and disease severity. Severity tends to be dictated by mutations in other genes (epistasis), as evidenced by distinct familial patterns in severity not tied to Waardenburg mutation type. Mutations in both copies of PAX3 have sometimes led to death before or shortly after birth, and mice with loss-of-function mutations in both copies of the gene do not survive. Type 4 is caused by a mutation in any of a range of genes, the most common being SOX10, when it is classed as type 4C. Type 4A is caused by an autosomal dominant or autosomal-recessive mutation in the gene EDNRB. Type 4B is caused by an autosomal dominant or autosomal-recessive mutation in the gene EDN3.
no telecanthus, or apparent wider eye gap), but with the addition of Hirschsprungs disease, which is a congenital lack of nerves in the intestines leading to bowel dysfunction. Additionally, hearing loss is not as common as in type 2. Rarely, cleft lip has been reported in this form of Waardenburg syndrome.Type 4 can also be caused by a mutation in SOX10 (the same gene as in type 2E), in which it is known as type 4C; hearing loss is very common and severe in this type. PCWH
A mutation in SOX10, the gene involved in type 2E and type 4C, can sometimes result in the symptoms of both types (neurological symptoms, as sometimes seen in type 2E, and Hirschsprungs disease, as seen in type 4). When this happens, it is called peripheral demyelinating neuropathy–central dysmyelinating leukodystrophy–Waardenburg syndrome–Hirschsprung disease (PCWH). Cause
Waardenburg syndrome is caused by mutations in any of several genes that affect the operation of neural crest cells in embryonic development. Most types of Waardenburg syndrome are caused by autosomal dominant mutations. The few that are autosomal recessive are rare. In most cases, an affected person has inherited it from one parent with one of the dominant forms of the condition. A small percentage of cases result from spontaneous new mutations in the gene, where no family history of the condition exists.The neural crest is a group of temporary migratory cells that are left over after the neural tube has closed (neurulation), around the fourth week of embryonic development.