Genetics
Angelman syndrome results from absence of a functional copy of the UBE3A gene inherited from the mother.

• Microdeletion on maternal chromosome 15q11.2-q13
• UPD (loss of maternal chromosome 15 due to a trisomy rescue event)
• Abnormal methylation pattern (imprinting defect)
• Mutation of the UBE3A gene on the maternal chromosome 15

Incidence
Affects approximately 1 in 15,000 individuals

Symptoms/Characteristics

• Infants with Angelman syndrome appear normal at birth, but often have feeding problems in the first few months
• Noticeable developmental delays are seen by 6 to 12 months
• Seizures usually commence between 2 and 3 years of age
• Children may have an imbalance of eye muscles (strabismus), under-pigmented skin, hair, and eye color, and hyperactive lower limb deep tendon reflexes
• Hyperactivity, microcephaly, sleep disorders, ataxia, movement disorders (hand-flapping ) and balance disorders that can cause severe functional deficits
• Individuals with Angelman syndrome can have normal life spans and generally do not show developmental deterioration as they age

Facial Features

• Individuals with Angelman syndrome are characterized by macrostomia (a large mouth), a large jaw and open-mouthed expression, and an inclination for protruding the tongue
• In addition, they are often smiling and have frequent outbursts of laughter

Clinical Management

• Medical therapy for seizures is often necessary
• In order to reach their development potential, individuals with Angelman syndrome require physical and occupational therapies, communication therapy, and behavioral therapies