How is Angelman syndrome inherited?
Most of the genetic changes that cause Angelman syndrome happen randomly, during the formation of an egg or sperm, or very early during pregnancy. These changes are sporadic, meaning that they happen by chance. In this situation, the parents' chance of having another child with Angelman syndrome is felt to be the same as that for the general population.
Very rarely, a genetic mutation in the UBE3A gene may be passed on from an unaffected parent to a child. In this situation, the chance of having another child with Angelman syndrome is as high as 50%.