15q Angelman Syndrome

15q Angelman Syndrome

If you have just found out through prenatal testing that your baby has or may have 15q Angelman syndrome and are looking for more information, the Genetic Support Foundation is a good starting point. Below you will find information about this condition as well as a list of resources that can provide you with additional information and support. After reviewing the information below, if you have a question that you are having difficulty finding an answer for, please feel free to contact us. 

Overview of Important Information about Angelman syndrome

Angelman syndrome is associated with a variety of health and developmental concerns. It is important to remember that each individual with Angelman syndrome is unique. All individuals with Angelman syndrome have some degree of developmental and intellectual disabilities, and most of the time these disabilities are on the more severe end of the spectrum. Individuals with Angelman syndrome typically have seizures and may have eye disorders.  

What is life like for people with 15q Angelman syndrome?

People with Angelman syndrome can have loving relationships with friends and family, learn and make progress in their social skills and communication at their own pace. The majority of individuals with Angelman syndrome are expected to need support and care over their lifetime given their disabilities and health concerns.



What Causes Angelman syndrome?

There are several types of rare genetic changes that can cause Angelman syndrome. Each of these changes ultimately result in the loss of function of the maternally inherited (from the mother) gene known as UBE3A. The UBE3A gene is located on chromosome 15.  As with most all of our genes, we inherit our genes in matched pairs:  one copy from the egg of the mother and one copy from the sperm of the father.  While a loss of function of the UBE3A gene that is passed down specifically from the mother causes Angelman syndrome, there is nothing known at this time that a mother could do to cause or prevent these genetic changes from occurring.  

In some parts of the brain, only the maternal copy of this gene is active. If the maternal copy of this gene does not work, some parts of the brain will not have a working copy of the UBE3A gene and this causes the symptoms seen in Angelman syndrome.

Most of the time (about 70%), Angelman syndrome is caused by a “de novo” deletion of the UBE3A gene on the maternal copy of chromosome 15. This means that the deletion was not present in the mother– it is unique to that individual. A “de novo” genetic change  is one that appears in the egg or sperm or in the early embryo and is then copied into all future cells of that individual. Prenatal screening tests using cfDNA may report a higher chance of Angelman syndrome due the possibility of a deletion on chromosome 15.  

Angelman syndrome can also be caused by a change in the maternal UBE3A gene, but this is less common (about 11% of individuals with Angelman syndrome). Disruption of the part of DNA that turns on UBE3A on the maternal chromosome 15 can also cause Angelman syndrome by causing inactivation of this gene (about 3% of Angelman syndrome cases).

Angelman syndrome can be also caused when an individual receives two copies of chromosome 15 from the father (uniparental disomy) and therefore lacks the maternal copy of the UBE3A gene. This is rare and is the cause of Angelman syndrome in only about 2-7% of cases.



What are the Health and Developmental Concerns Associated with Angelman syndrome?

15q Angelman syndrome is associated with a variety of health and developmental concerns. Individuals with Angelman syndrome have developmental delays that become noticeable between 6 and 12 months old. Other health concerns appear after an individual with Angelman syndrome is one year old. These include intellectual disabilities, impaired speech, and difficulty with movement and balance. Other common symptoms include repeated seizures (epilepsy) and an especially small head (microcephaly).

Individuals with Angelman syndrome smile and laugh often. Hand and arm flapping motions are also characteristic of this syndrome. Children with Angelman syndrome can be excitable and have difficulty sleeping, but these symptoms often lessen with age.



If I have a baby with Angelman syndrome, what is the chance I will have another baby with this condition?

The chance of having another baby with Angelman syndrome depends on the type of genetic change that caused  Angelman syndrome in the individual. Angelman syndrome caused by a deletion in the maternal UBE3A gene or by uniparental disomy is usually not inherited from the parent and has a less than 1% chance of happening again in future children. Angelman syndrome caused by a mutation in the UBE3A gene has up to a 50% chance of reappearing in future children when the error was inherited from a parent. Genetic testing would be needed to find the cause of Angelman syndrome and determine the risk to future children.



How do parents of children with Angelman syndrome feel about raising a child with Angelman syndrome?



What is the treatment for Angelman syndrome?

There is no “cure” for Angelman syndrome, however treatments and medications can help individuals reach their full potential. Medication, such as anti-seizure treatments, can be used to treat various health concerns. Individuals with Angelman syndrome will need regular follow-up and treatment by a variety of health specialists to treat their specific needs. Intervention programs such as physical, communication, and behavior therapy can be very beneficial to individuals with Angelman syndrome.



What are the long term outcomes for individuals with Angelman syndrome?

It is important to recognize that the health and developmental effects of Angelman syndrome vary from person to person. Improvement in social interaction, motor skills, and communication can be expected with intervention programs. Individuals with Angelman syndrome have moderate to severe intellectual disabilities and developmental delays. People with  Angelman syndrome are expected to need care and support over their lifetime. Life expectancy is not expected to be shortened for those with Angelman syndrome.



How common is Angelman syndrome?

Angelman syndrome is believed to affect between 1 in 12,000 and 1 in 20,000 people.




Other Resources

The Angelman Syndrome Foundation  provides resources for education and support for those affected by Angelman syndrome.

ASSERT  is a UK based support group that provides resources for education about Angelman syndrome and funds research.

The Foundation for Angelman Syndrome Therapeutics (FAST) provides resources for education about Angelman syndrome and funds research.

The National Organization for Rare Disorders provides information about Angelman Syndrome as well as resources for support.

The Pacific NW Angelman Syndrome Foundation provides resources and support for individuals with Angelman syndrome and their families in Washington, Oregon, and Alaska.

References

Online Mendelian Inheritance in Man, OMIM®. Johns Hopkins University, Baltimore, MD. MIM Number: 105830: 08/09/2016: . World Wide Web URL: https://omim.org/

Angelman syndrome: National Library of Medicine (US). Genetics Home Reference [Internet]. Bethesda (MD): The Library; 2017 Jan 24. Angelman syndrome; [reviewed 2015 May; cited 2017 Jan 30]; [about 6 screens]. Available from: https://ghr.nlm.nih.gov/condition/angelman-syndrome

Dagli AI, Mueller J, Williams CA. Angelman Syndrome. 1998 Sep 15 [Updated 2015 May 14]. In: Pagon RA, Adam MP, Ardinger HH, et al., editors. GeneReviews® [Internet]. Seattle (WA): University of Washington, Seattle; 1993-2017. Available from: https://www.ncbi.nlm.nih.gov/books/NBK1144/


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