IGFBP1 and obesity due to melanocortin 4 receptor deficiency: In our case series, at baseline the activity of the GH-insulin-like growth factor-1 (IGF-1) system was impaired with low GH values, low total IGF-1 and in relation to the obesity low levels of free IGF-1 and non-suppressed IGF-binding-protein-1 (IGFBP-1).