The 4-fold increase in the catalytic efficiency of release of angiotensin by renin from oxidized angiotensinogen may seem small, but evidence that it is a sufficient cause of the resultant hypertension comes from the previous finding of a similar but even smaller increase in activity associated with hypertension, in a family with an angiotensinogen cleavage-site mutation and a history of pre-eclampsia (20). This evidence concerns the gene REN and Hypertension.