Heritability of Arterial Function, Fitness, and Physical Activity in Youth: A Study of Monozygotic and Dizygotic Twins

Objectives 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. Study design 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. Results 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 P P Conclusion 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.