Panel Discussion on Genetic and Environmental Factors in Human Hypertension

Abstract

The high incidence of hypertension in the Negro in the West Indies and United States and the infrequency of the disease in the African Negro were the focal point of Dr. Moser's presentation. The coincidence of a high salt intake in the Bahama population which he studied was emphasized as a possible "lead" for further study. Dr. Francis emphasized the value of a longitudinal and complete epidemiologic study in uncovering etiologic factors in hypertension. A definition of hypertension should not be based on any arbitrary blood pressure, but frequency distribution curves for an entire population should be studied together with selective group characteristics which might lead to a definition of susceptibles. Then a follow-up program might be devised which would identify the factors involved in the appearance or progression of hypertensive disease in the susceptible individual or the mild case. From this standpoint the situation in the Bahamas, where the life history of the disease was telescoped into a shorter time span, seemed ideal. Dr. Neel emphasized the almost certain heterogeneity of the hypertensive trait, as proposed by Professor Pickering, and other difficulties in making genetic studies in this field: variations in blood pressure readings, effects of acquired diseases, and environmental influences such as the acculturation process at work in certain African populations. Prof. Moore reviewed the current surveys of the incidence of hypertension in certain populations. These support the concept of a continuous distribution of the blood pressure, of varying sex incidence depending on the age of the sample, and of a tendency to find an increase in the proportion of hypertensive subjects in older age groups. The failure of diastolic blood pressure to follow these patterns was an interesting and unexplained phenomenon. The value of longitudinal studies as in the Framingham survey, was demonstrated by the evidence of the reduced life expectancy which even mild degrees of hypertension imposed on the individual. In subsequent discussion, further information about blood pressure in East African populations was contributed by Drs. Perry and Grollman, and on blood pressure and dietary habits and diseases of Japanese, Eskimo, Central American, and Formosan populations were discussed by Drs. Kirkendall, Rodbard, Grollman, Stamler and Moser.