Heritability of arterial function, fitness, and physical activity in youth: a study of monozygotic and dizygotic twins.

Abstract

To examine the role of heredity in determining flow-mediated dilation in young people by comparing conduit artery endothelial function in monozygotic and dizygotic twins. We also determined relationships between physical activity and fitness in each twin subset. Flow-mediated dilation was assessed with high-resolution ultrasonography of the brachial artery in 22 twin pairs (11 monozygotic pairs 13.3 ± 1.6 years, 11 dizygotic pairs 13.6 ± 1.6 years). Fitness was assessed as peak oxygen uptake during an incremental treadmill test. Physical activity was measured with accelerometry. Twin versus twin intraclass correlations were performed for both groups. Flow-mediated dilation was significantly correlated in monozygotic twins only (r = 0.60, P = .02). Heritability of flow-mediated dilation was estimated at 0.44. Total PA time (monozygotic r = 0.77, dizygotic r = 0.60, P < .05) and light physical activity time (monozygotic r = 0.67, dizygotic r = 0.63, P < .05) correlated significantly in both groups. The peak oxygen uptake (r = 0.84, P < .01) was correlated only in monozygotic twins. Genetic factors appear to be responsible for a modest portion of the flow-mediated dilation response, suggesting that flow-mediated dilation can be influenced by environmental factors.