ESPE Abstracts

Background: Prader–Willi syndrome (PWS) is characterized by a switch from failure to thrive to excessive weight gain and hyperphagia with impaired satiety in early childhood. An elevated, more unfavorable ratio between acylated:unacylated ghrelin (AG:UAG) may be involved in the underlying mechanisms of this switch.

Objective and hypotheses: To assess the evolution of the appetite regulating hormones AG, UAG, and the AG:UAG ratio in infants with PWS and to investigate their association with the switch in eating behaviour.

Method: Longitudinal study in 36 infants with genetically confirmed PWS (age at inclusion 3 months–4 years). Serum AG and UAG levels were assessed 6-monthly for at least four times. AEBSF was used to inhibit deacylation of AG.

Results: Both AG and UAG levels were high in infants with PWS. AG levels decreased from the age of 3 months–2.5 years and subsequently increased. UAG levels slightly decreased in the first 2 years of life and subsequently sharply decreased. This resulted in a decreasing AG:UAG ratio in the first 2.5 years and an increase after this age. Infants in nutritional phase 1a, with hypotonia and difficult feeding, had an elevated AG:UAG ratio, which normalized in phase 1b, where the infants had an appropriate growth without difficult feeding. In phase 2a and above, when patients gained weight and became hyperphagic, the AG:UAG ratio increased again.

Conclusion: The switch in eating behavior in PWS is associated with an increase in AG:UAG ratio.