IGF1 and obesity due to melanocortin 4 receptor deficiency: It was demonstrated that craniofacial abnormalities, obesity and GH and IGF-1 alterations have similar effects on the magnitude of the development of nocturnal hypoxemia in patients with acromegaly.16 Moreover, in evaluating clinical data as predictors of this condition, it was found that neck circumference greater than 44 cm was the main factor involved, in comparison with other commonly implicated factors such as body mass index (BMI), daytime sleepiness and snoring.17