Diagnosis of Angelman Syndrome

Most A.S. children are diagnosed between the ages of 3 & 7 when the characteristic physical and behavioural features become evident.

The characteristics used for diagnostic criteria are listed below:

Consistent (100%)

• Developmental delay, functionally severe
• Speech impairment, no or minimal use of words, receptive and non-verbal communication skills higher than verbal ones
• Movement or balance disorder, usually ataxia of gait and/or tremulous movement of limbs
• Behavioural uniqueness: any combination of frequent laughter/smiling; apparent happy demeanour; easily excitable personality, often with hand flapping movements; hypermotoric behaviour; short attention span

Frequent (more than 80%)

• Delayed, disproportionate growth in head circumference, usually resulting in microcephaly (absolute or relative) by age 2
• Seizures, onset usually <3 years of age
• Abnormal EEG, characteristic pattern with large amplitude slow-spike waves (usually 2-3/s) facilitated by eye closure

Associated (20-80%)

• Flat occiput (bone at the back of the skull)
• Occipital groove
• Protruding tongue
• Tongue thrusting; suck/swallowing disorders
• Feeding problems during infancy
• Prognathia (protruding lower jaw)
• Wide mouth, wide-spaced teeth
• Frequent drooling
• Excessive chewing/mouthing behaviours
• Strabismus
• Hypopigmented skin, light hair and eye colour (compared to family), seen only in deletion cases
• Hyperactive lower limb deep tendon reflexes
• Uplifted, flexed arm position especially during ambulation
• Increased sensitivity to heat
• Sleep disturbance
• Attraction to/fascination with water