IGF1 and hyperinsulinemic hypoglycemia, familial, 4: Children with PWS have impaired growth, most likely caused by a combination of growth hormone (GH)/insulin-like growth factor 1 (IGF-1) deficiency and a lack of pubertal growth spurt (Driscoll et al., 1993; Grugni et al., 2011; Bakker et al., 2017).