The following information may help to address your question:
How is Waardenburg syndrome type 2 inherited?
type 2 (WS2) is usually inherited
in an autosomal dominant
This means that having a change (mutation
) in only one copy of the responsible gene
in each cell
is enough to cause features of the condition.
In some cases, an affected person inherits the mutated gene from an affected parent. In other cases, the mutation occurs for the first time in a person with no family history
of the condition. This is called a de novo
mutation. When a person with a mutation that causes an autosomal dominant condition has children, each child has a 50% (1 in 2) chance to inherit that mutation.
WS type 2D
is the only subtype reportedly inherited in an autosomal recessive
This means that to be affected, a person must have a mutation in both copies of the responsible gene in each cell. Affected people inherit one mutated copy of the gene from each parent, who is referred to as a carrier
. Carriers of an autosomal recessive condition typically do not have any signs or symptoms (they are unaffected). When 2 carriers of an autosomal recessive condition have children, each child has a:
- 25% (1 in 4) chance to be affected
- 50% (1 in 2) chance to be an unaffected carrier like each parent
- 25% chance to be unaffected and not be a carrier
Identifying the gene responsible for WS2 is necessary to determine the subtype that is present in a person or family.
People with questions about genetic risks or genetic testing
for themselves or family members should speak with a genetic counselor
or other genetics professional. A genetics professional can help by:
- thoroughly evaluating the family history
- addressing questions and concerns
- assessing recurrence risks
- facilitating genetic testing if desired
- discussing reproductive options
Last updated: 6/28/2016
How is Waardenburg syndrome diagnosed?
A diagnosis of Waardenburg syndrome (WS) is made based on the presence of signs and symptoms. In 1992, the Waardenburg Consortium proposed diagnostic criteria, which includes both major and minor criteria. A diagnosis of WS type 1 (the most common type) needs 2 major, or 1 major and 2 minor of the following criteria:
- Congenital sensorineural hearing loss (present from birth)
- Iris pigmentary (coloration) abnormality, such as heterochromia iridis (complete, partial, or segmental); pale blue eyes (isohypochromia iridis); or pigmentary abnormalities of the fundus (part of the eye opposite the pupil)
- Abnormalities of hair pigmentation, such as white forelock (lock of hair above the forehead), or loss of hair color
- Dystopia canthorum – lateral displacement of inner angles (canthi) of the eyes (in WS types 1 and 3 only)
- Having a 1st degree relative with Waardenburg syndrome
- Leukoderma (white patches of skin) present from birth
- Synophrys (connected eyebrows, or "unibrow") or medial eyebrow flare
- Broad or high nasal bridge (uppermost part of the nose)
- Hypoplasia (incomplete development) of the nostrils
- Premature gray hair (under age 30)
WS type 2 has features similar to type 1, but the inner canthi of the eyes are normal (no dystopia canthorum present).
WS type 3 also has similar features to WS type 1, but is additionally characterized by musculoskeletal
abnormalities such as muscle hypoplasia; flexion contractures
(inability to straighten joints); or syndactyly
(webbed or fused fingers or toes).
WS type 4 has similar features to WS type 2, but with Hirschsprung disease
(a condition resulting from missing nerve cells in the muscles of part or all of the large intestine).
Last updated: 2/11/2016
How are Waardenburg syndrome type 2 and its subtypes diagnosed?
Waardenburg syndrome type 2 (WS2) is diagnosed by the presence of 2 of the 5 major criteria needed for a general diagnosis of Waardenburg syndrome
, with no dystopia canthorum (lateral displacement of the inner canthi of the eyes).
In contrast to the general diagnosis of WS2, made based on symptoms, the diagnosis of a subtype of WS2 relies on identifying the genetic cause of WS2. For some subtypes, the general location (locus
) of the responsible gene is known, but the specific responsible gene has not yet been identified. There are currently 5 subtypes of WS2:
- Type 2A is caused by a change (mutation) in the MITF gene on chromosome 3
- Type 2B is associated with a locus on chromosome 1
- Type 2C is associated with a locus on chromosome 8
- Type 2D is caused by mutations is the SNAI2 gene on chromosome 8
- Type 2E is caused by mutations in the SOX10 gene on chromosome 22
Last updated: 6/28/2016
How can I find a genetics professional in my area?
Last updated: 12/6/2017
We hope this information is helpful. We strongly recommend you discuss this information with your doctor. If you still have questions, please
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