In humans, disruption of the hypothalamic – pituitary – growth hormone axis (growth axis) occurs as a consequence of over production of growth hormone and downstream hormones often caused by pituitary tumours in pituitary gigantism or acromegaly (occurring before or after epiphysial fusion of the long bones respectively) or by congenital or acquired growth hormone deficiency. This evidence concerns the gene GH1 and pituitary tumor.