Mental Deficiency and Developmental Testing

Developmental testing is compromised in AS individuals due to attention deficits, hyperactivity and lack of speech and motor control. In such situations, test results are invariably in the severe to profound range of functional impairment. It is possible however that the cognitive abilities in AS are higher than indicated from developmental testing. Nevertheless the developmental delay is still consistently in the functionally severe range and formal psychometric testing seem to indicate a ceiling for developmental achievement at around the 24-30 month range [1-3]. In general, Angelman syndrome individuals have relative strengths in nonverbal reasoning skills and with social interactions that are based on non-verbal events.

As we learn more about the different genetic classes of AS it appears that patients with the common chromosome deletion type of AS have relatively more severe developmental impairment. [4, 5] Older individuals with AS have been evaluated in terms of their adaptive functioning and the table, adapted from Summers and Pittman, lists some aspects of these studies [6].

Studies of Adaptive Functioning in AS

Study and Details
Findings
Smith et al., 1996 [7]
Ages 3-34 years, all had deletions
Teenager and adults were all dependent on assistance with feeding, toileting and dressing
Moncla et al., 1999 [8]
Ages 15-36 years; compared deletion to non-deletion cases
Vast majority with deletions were dependent on assistance for feeding, toileting and dressing; majority of non-deletion cases did not need assistance for dressing and feeding
Clayton-Smith, 2001 [9]
Adults 20-53 years; not in institutions and 82% had deletions
85% could perform a simple task such as holding a utensil
50% helped to undress themselves
57% remained dry during the day (clock-trained) and 11% overnight
Sandanam et al, 1997 [10]
Adult 24-36 years, all in institutions and all had deletions
All were dependent for activities of daily living

Many young adults with AS learn to respond to personal cues and interactions. Because of their interest in people, they express a broad repertoire of feelings and sentiments and form close bonds/attachments to others. Individuals with AS participate in group activities, household chores and in the activities and responsibilities of daily living. Like others, they enjoy most recreational activities such as TV/movies, listening to music, physical activity, going to the beach, etc. There is a wide range, however, in the developmental outcome so that not all individuals with AS attain the above noted skills. A few will be more impaired in terms of their mental retardation and lack of attention, and this seems especially the case in those with difficult to control seizures or those with extremely pronounced ataxia and movement problems. Fortunately, most children with AS do not have these severe problems, but even for the less impaired child, inattentiveness and hyperactivity during early childhood often give the impression that profound functional impairment is the only outcome possible. However, with a secure home and consistent behavioral intervention and stimulation, the AS child begins to overcome these problems and developmental progress occurs.


1. Didden R, Korzilius H, Duker P, et al. Communicative functioning in individuals with Angelman syndrome: a comparative study. Disabil Rehabil, 2004. 26(21-22): p. 1263-7.
2. Peters SU, Goddard-Finegold J, Beaudet AL, et al. Cognitive and adaptive behavior profiles of children with Angelman syndrome. Am J Med Genet A, 2004. 128(2): p. 110-3.
3. Trillingsgaard A and Ostergaard JR. Autism in Angelman syndrome: an exploration of comorbidity. Autism, 2004. 8(2): p. 163-74.
4. Clayton-Smith J and Laan L. Angelman syndrome: a review of the clinical and genetic aspects. J Med Genet, 2003. 40(2): p. 87-95.
5. Lossie AC, Whitney MM, Amidon D, et al. Distinct phenotypes distinguish the molecular classes of Angelman syndrome. J Med Genet, 2001. 38(12): p. 834-45.
6. Summers JA and Pittman D. Angelman Syndrome, in Demystifying syndromes: Clinical and educational implications of common syndromes associated with persons with intellectual disabilities, D., G. and R., K., Editors. 2004, NADD Press: New York. p. 161-188.
7. Smith A, Wiles C, Haan E, et al. Clinical features in 27 patients with Angelman syndrome resulting from DNA deletion. J Med Genet, 1996. 33(2): p. 107-12.
8. Moncla A, Malzac P, Voelckel MA, et al. Phenotype-genotype correlation in 20 deletion and 20 non-deletion Angelman syndrome patients. Eur J Hum Genet, 1999. 7(2): p. 131-9.
9. Clayton-Smith J. Angelman syndrome: Evolution of the phenotype in adolescents and adults. Dev Med Child Neurol, 2001. 43: p. 467-480.
10. Sandanam T, Beange H, Robson L, et al. Manifestations in institutionalised adults with Angelman syndrome due to deletion. Am J Med Genet, 1997. 70(4): p. 415-20.