The range of tumours removed during surgery is broadly reflective of the diverse aetiology of both CDI and HP: 45% of CDI patients had surgery for craniopharyngioma, a common cause of CDI, compared to just one CC patient; 25% of CDI patients had a history of tumours producing either growth hormone, prolactin, or both, compared to 40% of CC patients; and 10% of CDI patients had non-functioning pituitary adenomas, compared to 33% of CC patients. This evidence concerns the gene GH1 and neoplasm.