Angelman syndrome (AS) is a genetic disorder that mainly affects the nervous system. Angelman syndrome is due to a lack of function of part of chromosome 15 inherited from a person's mother. Most of the time, it is due to a deletion or mutation of the UBE3A gene on that chromosome. Occasionally, it is due to inheriting two copies of chromosome 15 from a person's father and none from their mother. As the father's versions are inactivated by a process known as genomic imprinting, no functional version of the gene remains. Angelman syndrome is typically due to a new mutation rather than one inherited from a person's parents. It is named after British pediatrician Harry Angelman, who first described the syndrome in 1965.An older term, "happy puppet syndrome", is generally considered pejorative.
- Developmental delay
- Speech impairment
- Movement or balance disorder, usually ataxia of gait and tremulous movement of limbs
- Behavioral characteristic any combination of atypical frequent laughter/smiling, atypically happy demeanor; easily excitable personality, often with hand flapping movements, hypermotoric behavior, short attention span.
- Hypopigmented skin and eyes
- Tongue thrusting; suck/swallowing disorders
- Hyperactive tendon reflexes
- Feeding problems during infancy
- Uplifted, flexed arms during walking
- Prominent mandible
- Increased sensitivity to heat
- Wide mouth, wide-spaced teeth
- Sleep disturbance
- Frequent drooling, protruding tongue
- Attraction to/fascination with water
- Excessive chewing/mouthing behaviors
- Flat back of head
- Smooth palms
- A history of delayed motor milestones and then later a delay in general development, especially of speech
- Unusual movements including fine tremors, jerky limb movements, hand flapping and a wide-based, stiff-legged gait.
- Characteristic facial appearance
- A history of epilepsy and an abnormal EEG tracing.
- A happy disposition with frequent laughter
- A deletion or inactivity on chromosome 15 by array comparative genomic hybridization (aCGH) or by BACs-on-Beads technology.
- Seizures are a consequence, but so is excessive laughter, which is a major hindrance to early diagnosis.