Considering that this correlation was lost when NF-PitNETs and somatotrophinomas were analysed separately, it is unlike that IGF-1 on its own explains the vascular differences within, and possibly between, somatotrophinomas and NF-PitNETs, and this observed correlation for the whole PitNET cohort occurred only because somatotrophinomas, which have by definition elevated IGF-1 levels, had smaller vessels than NF-PitNETs. The gene discussed is IGF1; the disease is growth hormone-producing pituitary gland adenoma.