UBE3A (see Causes of Angelman Syndrome and Development)
UBE3A mutations (11% of cases) – In these individuals, mutations in the UBE3A gene prevent its expression or function. Thus these individuals do not have the appropriate levels of functional UBE3A in the brain.
Uniparental Disomy (see Causes of Angelman Syndrome and Development)
(UPD; 7% of cases) – in UPD, the individual has two copies of paternal Chromosome 15. Because UBE3A is not expressed from the paternal copy, these individuals lack normal levels of UBE3A in the brain.