What Is Angelman Syndrome?

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  • Topic: Angelman syndrome, UBE3A, Chromosome 15
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  • Published : January 9, 2011
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Angelman Syndrome

What is Angelman Syndrome?

Angelman syndrome is a neuro-genetic disorder first described in 1965 by Dr. Harry Angelman. This is where the name of the disorder derived. Dr. Angelman referred to the disorder as ‘Happy Puppet Syndrome’, because the people affected with it generally had a happy, puppet like demeanor, and walked in a stiff, jerky, marionette-like gait. Angelman Syndrome affects about 1 in every 20,000 people. The life span of an individual affected with this syndrome is no different from the average life expectancy. (Angelman Syndrome New Zealand)

How does a person inherit Angelman Syndrome?

The most common cause of Angelman Syndrome
is a deletion in chromosome 15. This accounts for about
68% of the occurrences of Angelman Syndrome. As you
can see in the picture to the left, section q12 gets deleted from the long arm of chromosome 15. (Angelman Syndrome Foundation Inc)

Though much less common, and only responsible for about 3% of cases, it is possible to have two paternal copies of the chromosome 15 inherited, and no maternal chromosome 15. This is called Paternal Uniparental Disomy. [See picture to the right] Since normally the maternal gene is expressed, and in this case, it is absent, Angelman Syndrome will occur. (Angelman Syndrome Foundation Inc)

If there is a mutation in the gene, and it
overlaps with what is called the UBE3A gene and
causes a mutationin that as well, Angelman Syndrome
will occur if the mutation is on the maternally inheritetd chromosome 15. [See picture to the left] This accounts for about 13% os Angelman Syndrome occurences. (Angelman Syndrome Foundation Inc)

In about 6% of Angelman cases, there is a defect in the imprinting center. The imprinting center is located in the q12 region of chromosome 15, and controls whether the gene for Angelman Syndrome is turned on or off. If the Imprinting Center on the maternal chromosome 15 is defective, Angelman Syndrome will result. (Angelman Syndrome Foundation Inc)

Symptoms of Angelman Syndrome

The symptoms of Angelman Syndrome include:

▪ Under developed or absent speech skills
▪ Slow physical development
▪ Small head size
▪ Seizures/Epilepsy
▪ Jerky movements, especially hand flapping
▪ Problems with balance/unstable, jerky gait
▪ Protruding jaw/wide spaced teeth
▪ Happy appearance/Excessive laughter
▪ Slow to develop motor skills
▪ Sleep disturbance
▪ Short attention span/Hyperactive
(Angelman Syndrome New Zealand)

Angelman Syndrome is often misdiagnosed as Autism or Cerebral Palsy because of the characteristic hand flapping, and the similarities with the hindering of mental and physical development. The most common test to check for Angelman Syndrome is the FISH test. This test will check for deletions in Chromosome 15, the most popular cause of Angelman Syndrome. However, there are also tests like the UBE3A Gene Testing, DNA marker analysis and more that can test for the different ways of developing Angelman Syndrome. You can see the process of diagnosis in the diagram to the left. (Angelman Syndrome Foundation Inc)

How is Angelman Syndrome treated?

Like any genetic disorder, there is no cure for Angelman Syndrome. However, patients can attend different types of therapy. Behavioral therapy can help with the short attention span and hyperactive nature. Communication therapy can help by teaching people affected with Angelman syndrome other ways of communication, since they do not usually develop verbal skills. Physical therapy may help slightly stabilize their jerky gait. These types of things can help the people affected with Angelman Syndrome to develop to their full potential. There are also medications that can help with the epilepsy that...
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