Background: Coronary artery calcification (CAC) is associated with an increased risk of cardiovascular disease; little is known, however, about thoracic aortic calcification (AC). Our goal was to characterize risk factors for CAC and AC and to estimate the genetic contribution to their variation.
Methods and results: The presence and quantity of CAC and AC were measured with electron beam computed tomography and fasting blood tests and cardiovascular risk factors were obtained in 614 asymptomatic Amish subjects. CAC prevalence was higher in men than women (55% versus 41%; P<0.0001), although there was no sex difference in AC prevalence (51% and 56% in men and women, respectively; P=0.95). Age was more strongly associated with AC presence (odds ratio [OR], 2.7 for 5 years) than CAC presence (OR, 1.9 for 5 years) (homogeneity P=0.001). Subjects with AC had a 3.3-fold higher odds of having CAC. Heritabilities of CAC and AC presence were 0.27+/-0.17 (P=0.04) and 0.55+/-0.18 (P=0.0008), respectively, whereas the heritabilities of quantity of CAC and AC were 0.30+/-0.10 (P=0.001) and 0.40+/-0.10 (P<0.0001), respectively. The genetic correlation between CAC and AC quantity was 0.34+/-0.19, whereas the environmental correlation between these 2 traits was 0.38+/-0.09.
Conclusions: CAC and AC have similar risk factors, except male gender is associated only with CAC and age is more strongly associated with AC. The patterns of correlations suggest that CAC and AC share some common sets of genes and environmental factors, although it is likely that separate genes and environmental factors also influence calcification at each site.