Heredity, stress and blood pressure, a family set method--III. Family aggregation of hypertension

Genetic and nongenetic determinants of blood pressure in a southern Brazilian sample

A probabilistic sample representative of the adult population of Rio Grande do Sul, Brazil, was studied to estimate the genetic and nongenetic determinants of blood pressure. Four thousand five hundred and sixty-five individuals, 20 to 74 years old, from 2050 households, were examined. The genetic determination of the SBP (systolic blood pressure) and DBP (diastolic blood pressure) was evaluated in 557 families extracted from this sample. The analysis was performed first with no adjustments for other influencing factors, and then adjusting for the effects of the two significant covariates, age and Quetelet's index, identified through a multiple stepwise regression analysis with nine independent variables. Higher heritability estimates were obtained for DBP (raw data: 0.40; residuals: 0.45) than for SBP (raw data: 0.22; residuals: 0.26). The significant correlation coefficients varied from 0.13 (for father-offspring raw data, total sample), to 0.36 (for siblings, adjusted data, untreated sample). Slight differences were observed between the total and pharmacologically untreated samples in relation to correlation and heritability estimates.

Genetic analysis of serum lipid levels and blood pressure in a large kindred

A 267-member Caucasian kindred with a high incidence of cardiovascular disease, originally from Evans County, Georgia, was chosen for genetic analysis of serum lipid levels and blood pressure. Total serum cholesterol, triglycerides, high density lipoprotein cholesterol (HDL), and systolic and diastolic blood pressures were natural logarithm transformed and then adjusted for significant age, sex, and behavioral trait effects. Major gene pedigree analysis was used to estimate genetic parameters and to test hypotheses about the mode of transmission of each trait. Multivariate methods were also used to estimate linear combinations of the variables that best fit genetic models. The data were consistent with a major gene segregating for high levels of triglycerides in this kindred. However, dominant and recessive hypotheses could not be distinguished. Although diastolic blood pressure fit a mixture of two distributions significantly better than a single normal, major gene hypotheses could be rejected while the no-transmission hypothesis could not. There was no evidence of a major gene effect on cholesterol, HDL, systolic blood pressure, or any of the hypothetical traits represented by linear functions of the physical-lipid traits.

Heredity, stress and blood pressure, a family set approach: the Detroit Project revisited

Earlier conclusions from the Detroit Project utilizing an innovative "family sets" approach indicated that unspecified environmental factors, rather than genes, are the main determinants of blood pressure variation in blacks and whites. We report new estimates of the fraction of variation in blood pressure associated with genetic differences among individuals obtained under two methodologies: the method originally proposed for family sets and a maximum likelihood method. The family sets estimates of heritability were significant for systolic and diastolic blood pressure in both blacks and whites. Estimates for both the likelihood analysis and family sets method are within the range of estimates reported in other studies. In the present study all sets collected were included, the sets were stratified only by race and a different estimate of variance for the family sets estimate of heritability was used. The discrepancies between results presented here and the original study are attributed to these three factors.