Angelman syndrome (AS) is a genetic disorder that occurs in approximately 1 in 15,000 children, causing developmental disabilities and neurological problems, such as difficulty speaking, balancing, and walking, and in some cases, seizures.
Smiling often and outbursts of laughing are common for people with Angelman syndrome and many people with the syndrome have happy, excitable personalities.
For those with the syndrome, signs may not be noticed until developmental delays are present, generally around six to twelve months of age. Seizures most often begin when then child is between two and three-years old.
The most common age of diagnosis is between two and five years, when the distinguishing behaviors and features are the most apparent. Children with Angelman syndrome often, but not always, share the same facial features including a wide mouth, protruding tongue, and a prominent chin. However, most children with the syndrome share the same facial traits of their family, so it is uncommon for them to be considered to have an abnormal facial appearance.
In 1965, Dr. Harry Angelman, an English physician, first described three children with characteristics now known as Angelman syndrome. He noted that all had a stiff, jerky walk, absent speech, excessive laughter, and seizures. It wasn’t until the 1980s, that it was discovered in North America.
In 1987, Ellen Magenis, a physician at the Oregon Health Science Center, identified children who were expected to have the Prader-Willi syndrome. However, these children had seizures and severe developmental delay, features not expected to be found for that syndrome.
It was quickly discovered that these children had deletions on the maternally-derived number 15 chromosome, whereas in the Prader-Willi syndrome the deletion was always observed on the paternally-derived one. This was an important discovery and eventually paved the way for the explanation of several processes that caused Angelman syndrome.
Typical Angelman syndrome signs and symptoms include:
Developmental delays, such as lack of crawling or babbling at 6 to 12 months, and intellectual disabilities.
Lack of, or minimal speech.
Inability to walk, move, or balance well.
Trembling movement of arms and legs.
Frequent smiling and laughter.
A happy and excitable personality.
Other signs and symptoms may include:
Seizures, usually beginning between two and three years of age.
Stiff or jerky movements.
Small head size, with flatness in the back of the head.
Crossing of the eyes.
Walking with arms up in the air.
A lower jaw that protrudes out.
Light pigmentation in hair, skin and eyes.
Angelman syndrome is a genetic disorder, most often caused by problems with a gene (called the ubiquitin-protein ligase E3A (UBE3A) gene) located on chromosome 15.
Genes are segments of DNA that provide the blueprints for all of a person’s characteristics. When humans receive their genes, which occur in pairs, from their parents: one comes from the mother (maternal copy), and one comes from the father (paternal copy).
Both genes in a pair usually are active, but in a small number of genes, only one copy of a gene pair is active. When the copy that's usually active is missing or defective, it causes problems in the functions and characteristics controlled by that gene.
Normally, only the maternal copy of the UBE3A gene is active in the brain. Most cases of Angelman syndrome occur when part of the maternal chromosome 15 is missing or damaged. In a small number of cases, Angelman syndrome is caused when two paternal copies of the gene are inherited.risk-factors complications
Complications associated with Angelman syndrome include feeding difficulties during the first few months of life, hyperactivity, and sleep disorders.
Feeding difficulties result from the inability to coordinate sucking and swallowing. Hyperactivity often decreases with age, and medication generally is not necessary. Sleep disorders, however, are common for people with Angelman syndrome and medication or behavior therapy is sometimes ordered.
Tests and diagnosis
When Angelman syndrome is suspected, a blood sample is taken for genetic research to reveal the chromosome defects related to Angelman syndrome.
Treatments and drugs
Because chromosome defects cannot be repaired, there is no cure for Angelman syndrome. Treatment focuses on managing the medical and developmental problems that the chromosome defects cause.
Depending on the signs and symptoms a person exhibits, treatment for Angelman syndrome may include anti-seizure medication, physical therapy, communication therapy, and behavior therapy.
Due to people with Angelman syndrome not developing verbal language beyond simple sentences, communication therapy can help with nonverbal language skills such as sign language and picture communication.
In rare cases, Angelman syndrome may be passed from an affected parent to child through defective genes. For those with a family history of Angelman syndrome, or if you have a child with Angelman syndrome, you may wish to speak to a doctor or genetic counselor for help planning in future pregnancies.
To learn more about AS, check out the following links:
Angelman Syndrome Foundation
Foundation for Angelman Syndrome Therapeutics
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