A role for the immune system in hypertension was proposed in the 1960s (refs 31, 32) and is supported by the following observations: Immuno-compromised nude mice are less able to maintain hypertension in response to DOCA-salt treatment compared with immuno-competent mice33; thymus transplantation from WKY rats to SHR lowers blood pressure in SHR34; and dysfunction of immune cells caused by Rag-1 knockout/mutation or the immunosuppressant mycophenolate-mofetil blunts the elevated blood pressure in DOCA-salt treated animals or Dahl salt-sensitive rats35, 36, 37. The gene discussed is RAG1; the disease is Hypertension.