THE FAMILIAL OCCURRENCE OF HYPERTENSION AND CORONARY ARTERY DISEASE, WITH OBSERVATIONS CONCERNING OBESITY AND DIABETES

Abstract

The prevalence of hypertension, coronary artery disease, obesity and diabetes among the parents, grandparents, aunts and uncles of 266 Johns Hopkins medical students was ascertained. At a mean age of 55, 12.0% of parents had hypertension and 5.5% had coronary artery disease. A total of 16.0% of parents had hypertension and/or coronary artery disease, whereas 30.7% of grand-parents were known to be similarly affected. The incidence rates of these disorders among the parental siblings were slightly lower than the corresponding rates for parents. The incidence of hypertension tended to be higher among females than among males in comparable groups. Coronary artery disease occurred more often among males than among females; this difference was more pronounced in the parents'' generation. Of the parents, 12.2% were obese, while 9.3% of the grandparents were so affected. Diabetes was the least prevalent disorder, affecting 2.4% of the parents, with an incidence rate of 4.1% among the grandparents. In the search for evidence of causal interrelationships among the 4 disorders studied, it was found that combinations of 2 or more disorders affecting the same 951[1956] ANIMAL BEHAVIOR 9699-0705 individual occurred more frequently among both parents and grandparents than might be expected by chance alone. The degrees of association were particularly high between hypertension and coronary artery disease and between hypertension and obesity. Comparison of the incidence of other disorders in affected and in non-affected parents or grandparents again showed significant differences, pointing to the fact that hypertensive persons have more coronary artery disease and more obesity than normotensive persons. A study of the incidence of the 4 disorders in siblings of affected and non-affected parents showed that: (a) Hypertension was 3 times as frequent among siblings of hypertensive individuals as among siblings of normotensive individuals, (b) Coronary artery disease was nearly 4 times as prevalent among siblings of individuals with coronary artery disease as among siblings of persons withoutit, (c) The siblings of obese persons had 4 times as much obesity as the siblings of non-obese persons, (d) Diabetes was 8 times as common among siblings of non-diabetic persons. The incidences of the various disorders in 2 successive generations have been analyzed by comparing their prevalence among the offspring of matings where both, one, or neither of the parents was affected. In general, there was a distinct gradation among the offspring of these 3 types of mat- ings, with the highest incidence among the offspring of 2 affected parents and the lowest among the offspring of 2 unaffected parents. The genetic implications of the findings are discussed.