Fig. 1.

Pictured are individuals who have genetic test-proven Angelman syndrome. The mechanisms identified in them are: 15q11.2–q13 deletion (A, B, D, E); paternal uniparental disomy (C); UBE3A mutation (F, G) and imprinting defect (H). Individuals A, B and C illustrate some of the gait characteristics seen in the syndrome. Protruding tongue can be a noteworthy phenotypic feature, especially in combination with laughter (as in C), but most do not have pronounced tongue protrusion. The girl H has a non-deletion, mosaic-type imprinting defect, and thus her cognitive and language skills are relatively higher than observed in the typical child with the syndrome.