Physical Growth

Newborns appear to be physically well formed, but by 12 months of age some show a deceleration of cranial growth which may lead to relative or absolute microcephaly (absolute microcephaly means having a head circumference in the lower 2.5 percentile). The prevalence of absolute microcephaly varies from 88% [1] to 34% [2] and may be as low as 25% when non-deletion cases are also included. [3] Most AS individuals however have head circumferences less than the 25th percentile by age 3 years, often accompanied by a flattened back of the head. Average height is lower than the mean for normal children but most AS children will plot within the normal range. Final adult height has ranged from 4 foot 9 inches to 5 foot 10 inches in a series of 8 adults with AS. Familial factors will influence growth so that taller parents have AS children that tend to be taller than the average AS child. During infancy weight gain may be slow due to feeding problems but by early childhood most AS children appear to have near normal subcutaneous fat. In later childhood obesity can occur [4]. Food-related behaviors (e.g., eating non-food items, apparent increased appetite, increased behavioral orientation to food) are common in AS [5] and may contribute to obesity onset. Some weight gain can occur during young adulthood and obesity can be a management concern. Severe (e.g., morbid) obesity is a very uncommon occurrence in AS.


1. Zori RT, Hendrickson J, Woolven S, et al. Angelman syndrome: clinical profile. J Child Neurol, 1992. 7(3): p. 270-80.
2. Saitoh S, Harada N, Jinno Y, et al. Molecular and clinical study of 61 Angelman syndrome patients. Am J Med Genet, 1994. 52(2): p. 158-63.
3. Clayton-Smith J and Pembrey ME. Angelman syndrome. J Med Genet, 1992. 29(6): p. 412-5.
4. Clayton-Smith J. Clinical research on Angelman syndrome in the United Kingdom: observations on 82 affected individuals. Am J Med Genet, 1993. 46(1): p. 12-5.
5. Barry RJ, Leitner RP, Clarke AR, et al. Behavioral aspects of Angelman syndrome: a case control study. Am J Med Genet A, 2005. 132(1): p. 8-12.