For example, a meta-analysis of 23 case-control studies found no significant association between the ACE D allele and hypertension (OR 1.10, 95% CI: 0.95–1.27) [31], and a review of studies between 1997 and 2005 involving ACE and hypertension found 12 positive and 14 negative studies in humans [32]. This evidence concerns the gene ACE and Hypertension.