Distributions and Familial Studies of Blood Pressure and Serum Cholesterol Levels in a Total Community--tecumseh, Michigan.

THE question of the roles of heredity and environment is of prime importance to the understanding of the nature of chronic diseases. Genetic mechanisms must be known not only for a better understanding of pathogenesis but, to the extent to which genetic forces are operative, also to identify susceptible persons prior to the onset or full development of the pathological process. Knowledge of the way in which a genetic predisposition toward a chronic disease interacts with specific environmental forces may indicate the appropriate means for its control. Many disease entities are difficult to study in this way, largely because the threshold for recognition is poorly defined and frequently corresponds to a relatively late stage of the pathogenetic spectrum. In situations which are identified by a measurement, such as blood pressure or cholesterol levels, the precise identification of the threshold of abnormality is not necessary. Study of the distributions of these measures in a population, and of the degree of resemblance within families and kindreds presents a good opportunity to evaluate these relationships. The study of a total, natural community which is being conducted in Tecumseh, Michigan, provided an excellent setting for such an analysis.