Table 2.

Comparison of major phenotypes of different subtypes.

Major Aspects	AS Due to Maternal del15q11–13	AS Due to Non-Deletion
		Paternal Uniparental Disomy for Chromosome15q11–q13 (UPD)	Imprinting Defect	Pathogenic UBE3A Mutation
Development	More delayed across all development domains than other types Cognitive skills lower than other types Delayed gross and fine motor skills more severe Reduced developmental age regarding visual perception, receptive language, and expressive language	Higher overall age equivalent scores and growth score equivalents than deleion type but lower than UBE3A mutation subtype; Better development and expressive language ability in patients with UPD and imprinting defect Higher scores and greater rates of skill attainment in all development domains in patients UBE3A mutation
Seizures	More common and severe in the deletion group	Lower prevalence of epilepsy, and more with late-onset seizures. UPD subtype has the lowest frequency of epilepsy and exhibits the least severe epilepsy phenotype The severity of epilepsy in the UBE3A mutation subtype ranks second after the deletion subtype
Behavior	Lower response rates to the social reinforcement paradigm than other types	The imprinting defect a high rate of reinforcement by social stimuli. Patients with UBE3A mutations
Sleep	Common in all subtypes but Sleep problems are more prevalent in children with UPD and UBE3A mutations
Others	Higher rate of hypopigmentation	UPD and imprinting defects have a higher risk of obesity than deletion type