All relevant studies from all years, including both reviews and original articles, have been identified on the PubMed database by a literature search using the key MeSH terms “renin-angiotensin system,” “angiotensin II,” “ang III,” “ang IV,” “angiotensin converting enzyme,” “renin,” “ageing,” “senescence,” “angiotensin II receptors,” “AT1R,” “AT2R,” “ACE2,” “angiotensin (1-7),” “angiotensin (1-9),” and “angiotensin II and cardiovascular disease.” Nottingham University search, ClinicalTrials.gov, and Google Scholar were also used to collect pertinent studies. The gene discussed is REN; the disease is cardiovascular disorder.