While immune cell contribution to hypertension was discovered many years ago, it was not until the mid-2000s that a ground-breaking study by Guzik et al. showed that Rag1−/− mice lacking T and B cells were protected against angiotensin II (Ang-II) and deoxycorticosterone acetate salt-induced hypertension. The gene discussed is RAG1; the disease is hypertensive disorder.