Heart rate (HR), mean arterial pressure (MAP) and carotid intima-media thickness (cIMT)
are moderately heritable cardiovascular traits, but the environmental effects on the
longitudinal change of their heritability have never been investigated.368 Italian
and Hungarian twins (107 monozygotic, 77 dizygotic) underwent oscillometric measurement
and B-mode sonography of bilateral carotid arteries in 2009/10 and 2014. Within-individual/cross-study
wave, cross-twin/within-study wave and cross-twin/cross-study wave correlations were
estimated, and bivariate Cholesky models were fitted to decompose the total variance
at each wave and covariance between study waves into additive genetic, shared and
unique environmental components.For each trait, a moderate longitudinal stability
was observed, with within-individual/cross-wave correlations of 0.42 (95% CI: 0.33-0.51)
for HR, 0.34 (95% CI: 0.24-0.43) for MAP, and 0.23 (95% CI: 0.12-0.33) for cIMT. Cross-twin/cross-wave
correlations in monozygotic pairs were all significant and substantially higher than
the corresponding dizygotic correlations. Genetic continuity was the main source of
longitudinal stability, with across-time genetic correlations of 0.52 (95% CI: 0.29-0.71)
for HR, 0.56 (95% CI: 0.31-0.81) for MAP, and 0.36 (95% CI: 0.07-0.64) for cIMT. Overlapping
genetic factors explained respectively 57%, 77%, and 68% of the longitudinal covariance
of the HR, MAP and cIMT traits.Genetic factors have a substantial role in the longitudinal
change of HR, MAP and cIMT; however, the influence of unique environmental factors
remains relevant. Further studies should better elucidate whether epigenetic mechanisms
have a role in influencing the stability of the investigated traits over time.
