Use of certain drugs (androgens, progesterone, TNF-α inhibitors)Metabolic syndrome: obesity, non-alcoholic fatty liver diseaseEndocrine dysfunction (hypercortisolism, hypothyroidism, hyperprolactinaemia, acromegaly, type 2 diabetes mellitus)Pregnancy. The gene discussed is TNF; the disease is obesity due to melanocortin 4 receptor deficiency.