Evidence for Heritability of Abdominal Aortic Calcific Deposits in the Framingham Heart Study

Abstract

Background — Atherosclerosis is a systemic disease that underlies clinical cardiovascular disease. The radiographic finding of abdominal aortic calcific deposits is an indicator of the presence of aortic atherosclerosis and an independent predictor of cardiovascular disease events. Little is known about the heritability of aortic calcification. Methods and Results — Original Framingham Heart Study cohort participants (2151) in 1109 extended pedigrees had a lateral lumbar radiograph. The presence and severity of abdominal aortic calcific (AAC) deposits at the levels of the first through fourth lumbar vertebrae was graded by a previously validated rating scale. Correlation coefficients were calculated in pairs of siblings, parent-offspring, and spouses. Age-, sex-, and multivariable-adjusted correlation coefficients for AAC were 0.52 for parent-offspring pairs and 0.20 for sibling pairs. In contrast, the multivariable-adjusted correlation for AAC in spouse pairs was −0.02. Using variance component methods implemented in SOLAR, the estimated heritability for age-, sex-, and multivariable-adjusted AAC was 0.49 ( P <0.001). Thirty-one percent of the overall variance in AAC deposits was due to measured covariates, and 49% to heritable factors. Conclusions — In our large, population-based sample, heritable factors play a role in the presence and extent of abdominal aortic calcification. Thus, a substantial proportion of the variation in AAC is due to additive effects of genes, which have yet to be characterized. Measures of aortic atherosclerosis may provide heritable quantitative phenotypes for the genetic dissection of the complex condition of atherosclerosis in human populations.