Detection of genetic variance in blood pressure: The National Heart and Lung Institute Twin Study

The National Heart and Lung Institute Twin Study has examined 514 white adult male twins sets aged 42-56 at five centers in the United States. Blood pressure measurements for cotwins were obtained on the same day at the same center by different physicians according to a standardized protocol. The distributions of diastolic and systolic blood pressures in the twins were comparable to those observed in other populations. Significant differences centers ceters were observed no not differences by zygosity were demonstrable after adjustment was made for center differences. The data were analyzed by a method of Christian et al. which eliminates possible biases in estimated genetic variances that could result from different total variances in MZ and DZ twins. Results of the test for the presence of genetic variance indicate that both systolic and diastolic blood pressure are to a considerable extent genetically controlled with an estimated heritability of 0.8 for systolic and 0.6 for diastolic pressure. Although these findings are at variance with some previous reports, it is thought that much of the discrepancy results from application of different analytic techniques not in the data themselves. The application of these findings to our understanding of hypertension epidemiology and community hypertensive control programs are discussed.