ARE THERE INTERACTIONS AND RELATIONS BETWEEN GENETIC AND ENVIRONMENTAL-FACTORS PREDISPOSING TO HIGH BLOOD-PRESSURE

An overview of published observations suggests that both genetic predisposition and environment work together to produce hypertension in most persons. High blood pressure before age 55 occurs 3.8 times more often among persons with a strong positive family history of high blood pressure. Much of the total variability in blood pressure in modern populations seems attributable to genetic factors. Estimates of the proportion of the variance attributable to all genetic factors (heritability [H-2]) vary from 25% in pedigree studies to 65% in twin studies for sitting diastolic blood pressure. Several biochemical traits associated with high blood pressure are highly genetic (H-2, 78-84%) and may help elucidate the pathophysiology of high blood pressure. While pertinent environmental factors such as salt intake, alcohol use, and amount of exercise also correlate significantly among relatives, only 7% of the total variance of diastolic blood pressure seems attributable to all shared environmental factors in family households. Thus most familial aggregation of high blood pressure appears to be due to genes rather than shared family environment. Practical benefit may result from identifying familial predisposition in multiple siblings with high blood pressure before age 55 and lipid abnormalities (labeled "familial dyslipidemic hypertension"). About 12% of high blood pressure patients have familial dyslipidemic hypertension and also have high risk of early coronary heart disease. Hyperinsulinemia and central obesity as well as high triglycerides and low high density lipoprotein cholesterol are prominent features of familial dyslipidemic hypertension. If clinicians who evaluate and treat hypertension in adults under age 60 will also assess blood lipids and family history (of high blood pressure and coronary heart disease), they will find a subset of hypertensive patients with familial dyslipidemic hypertension who may benefit substantially from interventions such as exercise, weight reduction, and medications for both lipid abnormalities and elevated blood pressure.