The hereditary factor in arterial blood-pressure

Abstract

This report summarizes the genetic analysis of arterial-blood-pressure measurements obtained in the first four years of an epidemiological study of 612 families randomly selected from two populations in South Wales. No evidence is found in our data to suggest that arterial pressure is not a continuously variable characteristic, and in the absence of a sufficiently precise definition of essential hypertension to allow its genetic investigation in the general population we have used the appropriate system of quantitative analysis to investigate the simpler concept of multifactorial inheritance. If arterial pressure is determined by graded polygenic inheritance it would be expected that the relationship in pressure between relatives and propositi would be similar at all ranges of pressure, and that the data would fit a linear regression more and more closely as the errors were eliminated. This is what we have found. On the basis of Mendelian inheritance of a specific gene for essential hypertension it would be reasonable to expect that the accumulation of more data. and more reliable data, would reveal internal inconsistencies in such an analysis and would segregate the population into at least two groups in which the relationship in pressure between relatives and propositi was different. We found no evidence of these. It is possible that single-gene inheritance plays an important part in determining the arterial pressure of a very small fraction of the comm1Lunity, but our analyses suggest that in a representative sample of a general population which is experiencing what we take to be the usual morbidity and mortality associated with high blood-pressure this fraction is too small to be detected. For the majority of the population it appears that a regression of 0.287 for systolic pressures. and 0.224 for diastolic best summarizes the genetic resemblance of first-degree relatives. leaving between 55% and 77% of the systolic variance, and between 70% and 87% of the diastolic variance, for environmental factors to explain. © 1963, British Medical Journal Publishing Group. All rights reserved.