Endocrine Abstracts

Background: Prader-Willi syndrome (PWS) results from loss of paternally imprinted gene(s) from the 15q 11-13 region and is characterised by weight faltering during early childhood due to hypotonia, followed by obesity due to onset of the hyperphagic phase.

Aim of study: To determine the presence of an age zone during which excessive weight gain is particularly likely, in order to target counselling and dietary input.

Method: Body mass index (BMI) was calculated for each data point in 40 patients with PWS (M=24, F=16) from a single centre seen over a 20-year period. Two researchers independently scrutinised the chart for each patient and to estimate or identify the age at which an inappropriate rise in BMI began.

Results: Seventy-six patients were identified of which 36 had insufficient data for analysis leaving 40 for study. No inappropriate increase in BMI trend occurred in 10 patients, median (range) age at last data point 5.3 (1.5–15.2) years. Age at BMI increase could not be ascertained in 9 patients, all of whom became obese (BMI SDS >2) by 3.2 (2–5) years. Of 21 patients in whom age at BMI increase could be estimated (8) or precisely identified (13) the median age at the time of increase was 2 (0.5–3.8) years with 18/21 patients showing onset of increase between 1 and 2 years of age.

Conclusion: The critical age of excessive BMI increase in most PWS subjects is between 1 and 2 years. Structured input from a multidisciplinary team should be intensified at 1 year of life to pre-empt this trend.