Clinical Features of Angelman Syndrome

Clinical Features
Developmental and physical features
Angelman syndrome is usually not recognized at birth or in infancy since the developmental problems are nonspecific during this time. Parents may first suspect the diagnosis after reading about AS or meeting a child with the condition. The most common age of diagnosis is between three and seven years when the characteristic behaviors and features become most evident. A summary of the developmental and physical findings has recently been published (21) for the purpose of establishing clinical criteria for the diagnosis and these are listed below. All of the features do not need to be present for the diagnosis to be made, and the diagnosis is often first suspected when the typical behaviors are recognized.

Developmental History and Laboratory Findings
              Normal prenatal and birth history with normal head circumference; absence of major birth defects
              Developmental delay evident by 6 - 12 months of age
              Delayed but forward progression of development (no loss of skills)
              Normal metabolic, hematologic and chemical laboratory profiles
              Structurally normal brain using MRI or CT (may have mild cortical atrophy or dysmyelination)
Consensus Criteria for Clinical Features in Angelman Syndrome
Consistent (100%)
              Developmental delay, functionally severe
         Speech impairment, none 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
         Behavioral uniqueness: any combination of frequent laughter/smiling; apparent happy demeanor; easily excitable personality, often with hand flapping movements; hypermotoric behavior; 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
     Associated (20 - 80%)
         Strabismus
         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