Treatment[ edit ] Melatonin There is currently no cure available. The epilepsy can be controlled by the use of one or more types of anticonvulsant medications. However, there are difficulties in ascertaining the levels and types of anticonvulsant medications needed to establish control, because people with AS often have multiple types of seizures. Many individuals with Angelman syndrome sleep for a maximum of five hours at any one time[ citation needed ].
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Causes Many of the characteristic features of Angelman syndrome result from the loss of function of a gene called UBE3A. People normally inherit one copy of the UBE3A gene from each parent.
This parent-specific gene activation is caused by a phenomenon called genomic imprinting. If the maternal copy of the UBE3A 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 UBE3A 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 UBE3A gene. In a small percentage of cases, Angelman syndrome results when a person 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 UBE3A gene. These genetic changes can abnormally turn off inactivate UBE3A or other genes on the maternal copy of chromosome 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 cases. In some people who have Angelman syndrome, the loss of a gene called OCA2 is associated with light-colored hair and fair skin. The OCA2 gene is located on the segment of chromosome 15 that is often deleted in people with this disorder. However, loss of the OCA2 gene does not cause the other signs and symptoms of Angelman syndrome.
The protein produced from this gene helps determine the coloring pigmentation of the skin, hair, and eyes.
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