Based on the analysis of C3-deficient mice Zhou et al. suggested that “C3 may be a primary factor to activate the renal RA [renin-angiotensin] systems to induce hypertension” [29], Muscari et al. identified in a population study C3 as a predictor of myocardial infarction in men [30], and Engström et al. found that C3 is associated with the risk of developing hypertension [31]. Here, REN is linked to Hypertension.