Waardenburg Syndrome
Waardenburg syndrome (WS) is an
inherited disorder often characterized by varying degrees of hearing loss
and changes in skin and hair pigmentation. The syndrome got its name from
a Dutch eye doctor named Petrus Johannes Waardenburg who first noticed
that people with differently colored eyes often had a hearing impairment.
He went on to study over a thousand individuals in deaf families and found
that some of them had certain physical characteristics in common.
One commonly observed characteristic of Waardenburg syndrome is two
differently colored eyes. One eye is usually brown and the other blue.
Sometimes, one eye has two different colors. Other individuals with
Waardenburg syndrome may have unusually brilliant blue eyes.
People with WS may also have distinctive hair coloring, such as a patch of
white hair or premature gray hair as early as age 12. Other possible
physical features include a wide space between the inner corners of eyes
called a broad nasal root. In addition persons with WS may have low
frontal hairline and their eyebrows may connect. The levels of hearing
loss associated with the syndrome can vary from moderate to profound.
Individuals with Waardenburg syndrome may have some or all of the traits
of the syndrome. For example, a person with WS may have a white forelock,
a patch of white hair near the forehead and no hearing impairment. Others
may have white patches of skin and severe hearing impairment. The severity
of the hearing impairment varies among individuals with WS as do changes
in the skin and hair.
On rare occasions, WS has been associated with other conditions that are
present at birth, such as intestinal disorders, elevation of the shoulder
blade, and disorders of the spine. A facial abnormality, known as cleft
lip and/or palate, also has been associated with WS.
Types of WS
There are at least four types of Waardenburg syndrome. The most common
types of WS identified by scientists are Type 1 and Type 2. The different
types of physical characteristics a person has determines the type of WS.
Persons who have an unusually wide space between the inner corners of
their eyes have WS Type 1. Hearing impairments occur in about 20 percent
of individuals with this type of Waardenburg syndrome. Persons who do not
have a wide space between the inner corners of their eyes, but who have
many other WS characteristics are described as having WS Type 2. About 50
percent of persons with WS Type 2 have a hearing impairment or are deaf.
Cause
As a genetic disorder, Waardenburg syndrome is passed down from parent to
child much like hair color, blood type, or other physical traits. A child
receives genetic material from each parent. Because Waardenburg syndrome
is a dominant condition, a child usually inherits the syndrome from just
one parent who has the malfunctioning WS gene. Actually, there is a
50/50 chance that a child of an individual with WS will also have the
syndrome.
Research studies
Scientists have identified and located four different genes for
Waardenburg syndrome: PAX3, MITF, EDNRB, and EDN3. WS type 1 and 3 have
been associated with mutations in the PAX3 gene; WS type 2 with the MITF
gene; and WS type 4 with the EDNRB and EDN3 genes. While scientists are
studying all of these genes, currently, the most information is available
on the PAX3 and MITF genes and their role in Waardenburg syndrome.
The PAX3 gene is located on chromosome 2 and controls some aspects of the
development of the face and inner ear.
The MITF gene and is found on chromosome 3. It also controls the development of the ear and hearing. Scientists are now studying these genes to better understand how they operate in controlling the normal growth of the ear and the development of hearing. This information will help scientists understand why persons with WS sometimes develop hearing problems.
March 1999
NIH Pub. No. 91-3260
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