Angelman Syndrome
What is it?
Angelman syndrome (AS) is a neurological disorder
first described in 1965 by an English physician
named Dr. Harry Angelman. Symptoms are
usually evident after the age of three, and are
characterized by severe congenital mental
retardation, unusual facial appearance, and
muscular abnormalities.
Who gets it?
While an exact count of cases of Angelman Syndrome
in the United States is not available, the
Angelman Syndrome Foundation has knowledge of
around 1000 cases in the U.S. and Canada.
Angelman Syndrome is found among all racial
groups.
What causes it?
Researchers have found a very small deleted area
in chromosome 15 in patients with Angelman
Syndrome. This deleted area contains genes
that are activated or inactivated (turned on or
off) depending upon which parent the chromosome
was inherited from. The Angelman Syndrome
gene is called UBE3A. When this gene is
turned on, Angelman Syndrome does not occur.
However, when it is turned off or missing,
Angelman Syndrome occurs. In patients with
Angelman Syndrome, a missing UBE3A gene only
occurs in the chromosome given by the mother.
For this reason, it seems that the UBE3A gene is
turned on only on the chromosome inherited from
mother. Researchers have also found that
Angelman Syndrome is caused when a child inherits
both chromosomes 15 from the father. This
condition is called paternal uniparental disomy (UPD).
In this case, both chromosomes have Òturned offÓ
UBE3A genes on them. There is a control
region, called the Imprinting Center (IC), that
can control or turn on or off the action of the
UBE3A gene. Mutations in the area of the
Imprinting Center can also cause Angelman
Syndrome.
What are the symptoms?
Symptoms of Angelman syndrome include a stiff,
unstable jerky gait, absent or diminished speech
skills, hand flapping, excessive
laughter/unusually happy demeanor, developmental
delay, and small head size (microcephaly).
Some patients may also develop epilepsy and have
problems with balance.
How is it diagnosed?
Because it is difficult to detect the
developmental problems associated with Angelman
syndrome during infancy, children are usually
diagnosed with the disorder between the ages of
three and seven. Parents and doctors may notice a
developmental delay between the ages of 6 and 12
months, but because the child does reach most
developmental milestones during this stage, a
diagnosis cannot be made. Brain scans are
also normal at this time. By the age of two,
however, the child with Angelman Syndrome will
begin to show signs of microcephaly. By age
three, clinical features of Angelman Syndrome are
present, including speech impairment, movement or
balance disorder, frequent laughter and smiling,
easily excitable personality, hand flapping
movements, and short attention span.
Seizures may begin after the age of three.
An abnormal electroencephalograph (EEG), a
painless procedure in which wires are pasted to
the scalp to record the brain's electrical
activity, will also be found at this time.
Some children with Angelman Syndrome will also
have symptoms related to the mouth and jaw,
including protruding tongue or tongue
thrusting, sucking/swallowing disorders, feeding
problems during infancy; a jaw that projects
forward (prognathia), a wide mouth with
wide-spaced teeth, frequent drooling, and
excessive chewing/mouthing behaviors.
Children may also have an imbalance of eye muscles
so that one eye cannot focus with the other,
called strabismus; under-pigmented skin, hair, and
eye color; hyperactive lower limb deep tendon
reflexes; uplifted, flexed arm position especially
during movement; increased sensitivity to heat;
sleep disturbances; and an attraction
to/fascination with water.
What is the treatment?
Treatment of Angelman Syndrome is focused on
providing physical therapy and adaptive devices to
assist with gait and balance problems.
Speech therapy is recommended for language
problems. Patients with epilepsy are
prescribed anticonvulsant medications.
Self-care tips
There is no known way to prevent Angelman
Syndrome. Parents of children with these
types of disorders usually find strength, valuable
information, and comfort from support groups
dedicated to their particular disorder.
This information has been designed as a comprehensive and quick reference
guide written by our health care reviewers. The health information written
by our authors is intended to be a supplement to the care provided by your
physician. It is not intended nor implied to be a substitute for
professional medical advice.
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