Cushing’s syndrome is caused either by excessive medication of cortisol-like compounds or by tumors, such as pituitary and adrenal adenomas, which express high levels of the cortisol synthase gene CYP11B1 and thereby produce a high level of cortisol [84,85]. The gene discussed is CYP11B1; the disease is Cushing syndrome due to macronodular adrenal hyperplasia.