Heritability of venous function in humans

Objectives-Venous function contributes to the pathogenesis of thrombophlebitis, venous thrombosis, and possibly to arterial hypertension. Venous disease is presumably heritable; however, the genetic variance of venous function is unknown. Methods and Results-We determined the heritability of venous function in 46 twin pairs (24 monozygotic, age 35+/-11 years, 14 men, 34 women; 22 dizygotic, age 30+/-8 years, 19 men, 25 women). After a resting phase in the supine position, we determined venous function in both legs by impedance plethysmography. Venous capacity was determined by a standardized protocol. In addition, we obtained venous pressure volume curves by slowly deflating a thigh cuff from 60 to 0 mm Hg. Venous compliance was determined as the steepest part of the venous pressure volume curve. Heritability was estimated using a path modeling approach. Unadjusted heritability was 0.6 (P<0.05) for venous capacity and 0.9 (P<0.05) for venous compliance. The heritability estimate for venous capacity decreased to 0.3 after adjustment for age, body mass index, and body fat. The heritability estimate for venous compliance remained essentially unchanged after adjustment for sex and age. Conclusions-We conclude that venous function is strongly influenced by genetic factors. The genes involved may influence venous disease states.