Frequency of ABO and Rh Blood Groups and Their Association With Essential Hypertension

Abstract

The ABO and Rh systems are the blood groups most often recorded in clinical practice, and because they are cheap to determine they are also among the most frequently tested for association with common disease. Essential hypertension, the form of raised blood pressure with no single identifiable cause, has repeatedly been examined from this angle, with results that are scattered and often contradictory. This narrative review asks what the published literature actually supports. It covers the molecular basis of the two systems, the distribution of the groups between populations, the better-documented links between ABO and vascular and thrombotic disease, and the genetic and epidemiological evidence on blood pressure. The review reports no new data and no local frequencies. A plausible biological route exists for ABO, through von Willebrand factor and endothelial adhesion molecules, while for Rh the route is speculative. Genome-wide studies of blood pressure have not highlighted the ABO locus, and the direct hypertension literature consists largely of small, single-site comparisons that are vulnerable to population stratification, confounding and selective reporting. The balance of the evidence is that any association between blood group and essential hypertension is unproven, probably small if present, and not a basis for screening or counselling. The review closes with the design features a convincing study would need.