Angelman Syndrome

Angelman Syndrome is a genetic disorder that causes developmental delay and neurological problems. The physician Harry Angelman first delineated the syndrome in 1965, when he described several children in his practice as having “flat heads, jerky movements, protruding tongues, and bouts of laughter.” Infants with Angelman syndrome appear normal at birth, but often have feeding problems in the first months of life and exhibit noticeable developmental delays by 6 to 12 months. Seizures often begin between 2 and 3 years of age. Speech impairment is pronounced, with little to no use of words. Individuals with this syndrome often display hyperactivity, small head size, sleep disorders, and movement and balance disorders that can cause severe functional deficits. Angelman syndrome results from absence of a functional copy of the UBE3A gene inherited from the mother.

It is estimated that Angelman Syndrome occurs about one in 20,000 births. There is no cure.

Always Seen/Consistent (100%)

  • Severe intellectual disability and developmental delay (failure to match developmental milestones of other children), eg. delays in sitting and walking, delay in fine motor skills development and delay in toilet training;
  • Profound speech impairment: no speech or minimal use of words; receptive and non-verbal communication skills higher than verbal ones;
  • Movement for balance disorder (tremulous movement of limbs, stiffness and jerkiness in limbs) and ataxia of gait (lack of muscular co-ordination when walking);
  • Behavioural uniqueness: any combination of frequent laughter/smiling; Happy demeanour; easily excitable personality, often with hand flapping movements; short attention span and hyperactivity.

Usually Seen/Frequent (More than 80%)

  • Small head size – often by age two years; *Seizures – onset usually before three years of age; *Abnormal EEG (brain wave pattern irregularity).

Sometimes Seen/Associated (20% to 80%)

  • Flat occiput (flattened back of head);
  • Protruding tongue;
  • Tongue thrusting; suck/swallowing disorders;
  • Feeding problems during infancy;
  • Wide mouth, widely spaced teeth;
  • Frequent drooling;
  • Excessive chewing/mouthing behaviours;
  • Scoliosis (curvature of the spine);
  • Strabismus (crossed eye);
  • Hypo pigmented skin, light hair and eye colour (compared to family), a feature in deletion cases;
  • Wide based gait (feet far apart with flat, out turned feet);
  • Tendency to hold arms up and flexed while walking;
  • Increased sensitivity to heat;
  • Sleep disturbance;
  • Attraction to/fascination with water.

Not all features may be present. A diagnosis of Angelman Syndrome is based on a combination of the clinical features as above, together with genetic diagnostic tests.

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