Detection of genetic variance in blood pressure of seven-year-old twins.

Results from twin studies in older children and adults indicate that there is significant genetic variance for blood pressure (BP). Utilizing date which were collected in 12 US university-affiliated hospitals in 1966-1973 in the Collaborative Perinatal Project (NCPP), the authors sought to determine if the effects of heredity on BP variability are apparent in younger twins. BP was determined in 197 pairs of like-sexed twins at seven years of age. Significant genetic variability for diastolic blood pressure (DBP) was found in the twins, with a heritability estimate of 0.53. Systolic blood pressure (SBP) results tended in the same direction but were not statistically significant. The trends were comparable for both sexes and races. These findings suggest that even at a young age substantial genetic influences on DBP variability are detectable.