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.

Language disabilities in three twin pairs and their relatives.

Three pairs of monozygotic twins were ascertained during a general survey of language disabilities conducted among schoolchildren of Porto Alegre, Brazil. Two of them were concordant for dysgraphia, dysorthographia, dyslexia, and speech defects, while the other was concordant for dysorthographia and dyslexia, but discordant for dysgraphia. Two of the mothers and two sibs also presented language problems, but of a type that was not completely similar to those of the twins. Concomitant neurological and psychological studies, as well as the family histories, helped to understand the similarities and dissimilarities observed.

School achievement, intelligence, and personality in twins.

A sample of 47 MZ and 49 DZ pairs of Brazilian twins was investigated in relation to school achievement in six specific areas of study, as well as performance in the test of Dominoes, the Differential Aptitude Tests (DAT) and Grieger's Characterological Qur the school grades obtained in five of the six areas considered, as well as for their general average; the same being true for the results on the indicated measure of general intelligence, six of the eight DAT tests, and two of the characterological elements. There is a clear positive relationship between the grades earned by the twins and their performance in the Dominoes test. Achievement in Portuguese and foreign language correlates positively with DAT's Numerical Ability, Abstract Reasoning, and Clerical Speed and Accuracy. The results show an agreement with previous estimates of the genetic determination of these variables, which is to a certain extenet surprising if we consider the differences in sample sizes, age, and degree of schooling of the subjects, environmental differences, and the dissimilarities which exist between the homes and school systems of USA, Europe, and Brazil.