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Article Provided by The ARC of Georgia
Fact
Sheet:
Williams syndrome is a genetic disorder caused by missing genetic
material on one copy of chromosome 7. The problem is usually caused by
a random mutation, so parents may not have any family history of the
condition. It occurs in about 1 in 20,000 births.
Most young children with Williams syndrome are described as having
similar facial features. These features (which may not be apparent,
but can be recognized by a physician or geneticist), include a small
upturned nose, long philtrum (upper lip length), wide mouth, full
lips, small chin, and puffiness around the eyes. Blue and green-eyed
children with Williams syndrome can have a prominent "starburst" or
white lacy pattern on their iris. Facial features become more apparent
with age.
Most people with Williams syndrome have some degree of cognitive
disability. Young children with Williams syndrome often experience
developmental delays. Milestones such as walking, talking and toilet
training are often achieved somewhat later than is considered normal.
Distractibility is a common problem in mid-childhood, which appears to
get better as the children get older.
Older children and adults with Williams syndrome often demonstrate
intellectual "strengths and weaknesses." There are some intellectual
areas (such as speech, long term memory, and social skills) in which
performance is quite strong, while other intellectual areas (such as
fine motor and spatial relations) are significantly deficient.
When the characteristics of Williams syndrome are recognized, referral
to a clinical geneticist for further diagnostic evaluation is made.
The clinical diagnosis can be confirmed by a blood test. The technique
known as fluorescent in situ hybridization (FISH), a diagnostic test
of the DNA that detects the elastin deletion on chromosome #7 in more than
98% of individuals with Williams syndrome. It is likely that the
elastin gene deletion accounts for many of the physical features of
Williams syndrome.
In most families the child with Williams syndrome is the only one to
have the condition in his or her entire extended family. However, the
individual with Williams syndrome has a 50% chance of passing the
disorder on to each of his or her children.
Helpful Information:
Some medical and developmental problems are probably caused by
deletions of additional genetic material near the elastin gene on
chromosome #7. The extent of these deletions varies among individuals,
so you child may not have all of these conditions:
-
partial
absence of the teeth, defective tooth enamel, or small, widely-spaced
teeth
-
heart
failure (depending on degree of heart defect)
-
high blood
calcium level, hypercalcemia, that may cause seizures and muscle
rigidity
-
blood
vessel narrowing (One of the missing genes is the gene that produces elastin, a protein that gives elasticity to blood vessels and other
tissues in the body. It is likely that having only one copy of this
gene results in the narrowing of blood vessels.)
-
hypertension (depending on degree of blood vessel narrowing)
-
Joint
laxity which may progress to stiffness as the person gets older
-
Initially
delayed speech development may turn into relative loquacious speech
later and relatively strong learning by hearing
-
Distractibility
-
Clinodactyly (an inward bend of the small finger)
-
Personality traits include being overtly friendly, trusting strangers,
fear of loud sounds or physical contact, and an affinity for music
Your
doctor may do tests on your child, including, but
not limited to:
-
echocardiography with Doppler (may show blood vessel narrowing)
-
periodic
blood pressure check
-
kidney
ultrasound (some patients have renal defects)
-
blood test
for chromosome deletion that is called a FISH test (genetic defect
found in 98% of patients with Williams syndrome)
-
far
sightedness
Since some
of the medical problems can develop over time, it is important that
individuals with Williams syndrome receive ongoing medical monitoring
and supervision. Despite the possibility of medical problems, most
children and adults with Williams syndrome are healthy and lead
active, full lives.
Physical therapy can help with joint stiffness. Developmental and
speech therapy can also help. For example, their verbal strengths can
help compensate for other weaknesses.
Coordination of treatment by a geneticist experienced with Williams
syndrome can be beneficial.
Resources:
Williams Syndrome
Foundation
Williams Syndrome Association
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The impact of a
disability can always be lessened to some degree by early intervention. |
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