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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.
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