Search

Coronary artery calcification (CAC) and common carotid artery intima-media thickness (CIMT) are measures of subclinical vascular disease. This 2000–2006 study aimed to characterize the associations among coronary artery disease risk factors, CAC quantity, and CIMT and to estimate shared genetic and environmental contributions to both CAC and CIMT among 478 asymptomatic Amish adults in Lancaster County, Pennsylvania. Heritability for CAC quantity and CIMT, adjusted for age and sex, was 0.42 (P = 0.0001) and 0.29 (P = 0.003), respectively. CAC quantity and CIMT were modestly correlated (adjusted r = 0.14, P = 0.003) but showed little evidence of shared genetic or environmental factors. However, significant genetic correlations were found for CAC quantity and total cholesterol (0.44 (standard error, 0.19); P = 0.03), for CAC quantity and low density lipoprotein cholesterol (0.55 (standard error, 0.17); P = 0.005), and for CIMT and waist circumference (0.58 (standard error, 0.25); P = 0.046), suggesting shared genes for these risk factors and measures of subclinical disease. Results suggest that some of the same genes influence variation in CAC and low density lipoprotein cholesterol, whereas a different set of genes influences variation in CIMT and waist circumference. [ABSTRACT FROM AUTHOR]

Apolipoprotein C-III (apoC-III) inhibits triglyceride hydrolysis and has been implicated in coronary artery disease. Through a genome-wide association study, we have found that about 5% of the Lancaster Amish are heterozygous carriers of a null mutation (R19X) in the gene encoding apoC-III (APOC3) and, as a result, express half the amount of apoC-III present in noncarriers. Mutation carriers compared with noncarriers had lower fasting and postprandial serum triglycerides, higher levels of HDL-cholesterol and lower levels of LDL-choleslerol. Subclinical atherosclerosis, as measured by coronary artery calcification, was less common in carriers than noncarriers, which suggests that lifelong deficiency of apoC-III has a cardioprotective effect. [ABSTRACT FROM AUTHOR]