GH1 and sleep apnea syndrome: No difference in sleep or respiratory characteristics were found, however 20% of children developed OSA post-GH.<h4>Conclusion</h4>Initiation of GH therapy was not associated with a change in loop gain, suggesting that changes in ventilatory control are unlikely to contribute to the development of OSA in children with PWS.<h4>What is known</h4>• Prader-Willi syndrome is associated with abnormal ventilatory control and increased risk of sleep-disordered breathing.