Although it has frequently been indicated that the causes of essential hypertension are not known, this is only partially true because we have little information on genetic variations or genes that are overexpressed or underexpressed as well as the intermediary phenotypes that they regulate to cause high BP. 4 A number of factors increase BP, including (1) obesity,(2) insulin resistance,(3) high alcohol intake,(4) high salt intake (in salt-sensitive patients),(5) aging and perhaps (6) sedentary lifestyle,(7) stress,(8) low potassium intake, and (9) low calcium intake. 5, 6 Furthermore, many of these factors are additive, such as obesity and alcohol intake. In this review, variations in BP that are genetically determined will be called “inherited BP,” although we do not know which genes cause BP to vary; we know from family studies that inherited BP can range from low normal BP to severe hypertension. Factors that increase BP, such as obesity and high alcohol and salt intake, will be called “hypertensinogenic factors.” Some of these factors have inherited, behavioral, and environmental components. Inherited BP could be considered core BP, whereas hypertensinogenic factors cause BP to increase above the range of inherited BPs, thus creating 4 main possibilities:(1) patients who have inherited BP in the optimal category (120/80 mm Hg); if 1 or more hypertensinogenic factors are added, BP would probably increase but remain in the normal range (135/85 mm Hg)(Figure 1, first 2 columns);(2) patients who have inherited BP in the normal category (130/85 mm Hg); if 1 or more hypertensinogenic factors are added, BP will probably increase to the high normal range (130 to 139/85 to 89 mm Hg) or to stage 1 of the hypertensive category (140 to 159/90 to 99 mm Hg)(Figure 1, second 2 columns);(3) patients who have inherited BP in the high normal category (130 to 139/85 to 89 mm Hg); if 1 or more hypertensinogenic factors are added, BP will increase to the hypertensive range (140/90 mm Hg)(Figure 1, third 2 columns); and (4) patients who have inherited BP in the hypertensive range; addition of 1 or more hypertensinogenic factors will make hypertension more severe, changing it from stage 1 to stage 2 or 3 (Figure 1, fourth to sixth 2 columns). Theoretically, in a population unaffected by hypertensinogenic factors, BP will have a normal distribution; it will be skewed to the right and will have a narrow base or less variance (Figure 2, continuous line). When 1 hypertensinogenic factor is added to this population, such as increased body mass, one would expect the normal distribution curve to be further skewed to the right; consequently the base will be wider (more variance) and the curve will be flatter (Figure 2, broken line). If a second hypertensinogenic factor such as alcohol intake is added to increased body mass, the curve will be skewed more to the right and the variance will increase further, with more subjects classified as hypertensive (Figure 2, dotted line).

Discovering which genetic variations place BP on the left or right side of the distribution curve is of both theoretical and practical importance because it could help the physician to better treat or cure hypertension. 7 Recognition of the hypertensinogenic factors may allow nonpharmacological prevention, treatment, or cure of hypertension. Hypertensinogenic factors such as obesity, insulin resistance, or high alcohol intake also have an important genetic component. Furthermore, there are interactions between genetic and environmental factors (Figure 2) that influence intermediary phenotypes such as sympathetic nerve activity, the renin-angiotensinaldosterone and renal kallikrein-kinin systems, and endothelial …