REN and essential hypertension: RAAS genes encoding renin (REN), angiotensinogen (AGT), angiotensin-converting enzyme (ACE), angiotensin type 1 receptor (AGTR1) and aldosterone synthase gene (CYP11B2) have been widely investigated in different ethnic populations, and dozens of single nucleotide polymorphisms (SNPs) within RAAS genes have been reported to be significantly associated with essential hypertension [9]–[11].