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fragile x syndrome
Genetic Disorder List
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Angelman syndrome is a genetic disorder that causes developmental delay and neurological problems. It usually manifests itself during the first years of a child. The physician
first delineated the syndrome in 1965, when he described several children in his practice as having "flat heads, jerky movements, protruding tongues, and bouts of laughter."
that have Angelman Syndrome may appear normal at birth, but often can obtain feeding problems and can show obvious disabilities. Seizures cn begin to accure starting at 2 years old. Speech disabilities is also noticable, with little or even no words. Individuals with this syndrome often display hyperactivity, small head size, sleep disorders, and movement and balance disorders that can cause severe functional deficits. Angelman syndrome results from absence of a functional copy of the
gene inherited from the mother. The most hard and difficult disabilities that come with Angelman Syndrome is the sleeping habits and speech communications. Communication is an especially complex issue, because even though most AS individuals don't have any speech at all, they understand a lot of what is said to them. In order for easier ways for the affected person to express themselves, alternative methods of communication have to be established, which can be a long and difficult process.
Angelman syndrome is caused by these three main reasons:
-Deletion of the genes of Chromosome-15 from the mother's side.
-A mutation of the UBE3A gene.
-Translocation"exchange of chromosome parts" of the chromosome -15.
Approixmatly 75% of the people who have Angelman Syndrome have the same genetic faults.
On rare occassions, it is also caused when two paternal copies of the gene is inherited, when normally it would only be from one paternal and one maternal copy. (paternal uniparental disomy).
There are a variety of symptoms for people with Angelman Syndrome. 3/4 of the infants with this disease will have feeding problems. They can aquire delayed walking and sitting abilities. Their attention span is very short and have speech and communication problems, even when they reach their toddler years. They can also suffer from hyperactivity. When they grow older, they will have difficulty learning in school and may also suffer epilepsies. Infants will make unusual movements, experience shaking of the hands and fingers.
For non-infants, people with Angelman Syndrome will experience the same symptoms as infants would, but there are some other symptoms to watch for. Affected people will suffer from mental retardation, lack of speech skills, and learning disabilities. They can suffer from Ataxia , the inability to walk or move well. Their arms and hands may tremble/shake/and flip uncontrollably. They are seen to be happy, but they are uncontrollably smiling or laughing. They are also seen to have excited/happy behaviour.
Some people may also experience seizures, starting from ages 2-3. They may become very stiff, unable to move, or have jerky body movements to try and "break free:". May obtain strabimus, or the crossing of their eyes. They may have facial disablilites like tongue thrusting or a lower jaw that sticks out. They can seem to be walking with their arms in the air like they are happy. They can also obtain hypopigmentation, or to have light pigmentation in hair, skin, and eyes.
Is there any treatment?
There is no specific therapy for Angelman syndrome. Medical therapy for seizures is usually necessary. Physical and occupational therapies, communication therapy, and behavioral therapies are important in allowing individuals with Angelman syndrome to reach their maximum developmental potential.
There is no treatment for Angelman Syndrome because it's not an illness or bacterial illness, but a disorder, so there can be no treatment or cure. Allthough there is no true treatment to this disorder, there are plenty of therapies think about for the different symptoms. Some therapies include;
-physiotherapy, to prevent stiff joints
-speech therapy, to get passed speech and communication problems
What are the genetics changes related to Angleman Syndrome?
Many of the characteristic features of Angelman syndrome result from the loss of function of a gene called
. People normally inherit one copy of the
gene from each parent. Both copies of this gene are turned on (active) in many of the body's tissues. In certain areas of the brain, however, only the copy inherited from a person's mother (the maternal copy) is active. This parent-specific gene activation is caused by a phenomenon called genomic imprinting. If the maternal copy of the
gene is lost because of a chromosomal change or a gene mutation, a person will have no active copies of the gene in some parts of the brain.
Several different genetic mechanisms can inactivate or delete the maternal copy of the
gene. Most cases of Angelman syndrome (about 70 percent) occur when a segment of the maternal chromosome 15 containing this gene is deleted. In other cases (about 11 percent), Angelman syndrome is caused by a mutation in the maternal copy of the
In a small percentage of cases, a person with Angelman syndrome inherits two copies of chromosome 15 from his or her father (paternal copies) instead of one copy from each parent. This phenomenon is called paternal uniparental disomy. Rarely, Angelman syndrome can also be caused by a chromosomal rearrangement called a translocation, or by a mutation or other defect in the region of DNA that controls activation of the
gene. These genetic changes can abnormally turn off (inactivate)
or other genes on the maternal copy of chromosome 15.
A deletion of a gene called
is associated with light-colored hair and fair skin in some people with Angelman syndrome. The
gene is located on the segment of chromosome 15 that is often deleted in people with this disorder. The protein produced from this gene helps determine the coloring (pigmentation) of the skin, hair, and eyes.
The causes of Angelman syndrome are unknown in 10 to 15 percent of affected individuals. Changes involving other genes or chromosomes may be responsible for the disorder in these individuals.
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