RELATIVE ROLE OF GENES AND ENVIRONMENT ON BP - TWIN STUDIES IN MADRAS, INDIA

This study was conducted to test the feasibility of the twin research model in a developing country with diverse cultures and to understand the relative influence of genetic and environmental factors on BP vari ation among South Indians. This was a cross-sectional twin study of vo lunteers using a two-by-two factorial design for the analysis of quant itative traits. The factors were twin type (monozygotic and dizygotic) and sex (male and female). The study was conducted in Madras. Twenty- four pairs of twins were contacted for participation in the project. O f the 24 pairs we contacted, 91% (20) actually participated in our stu dy. Among 20 sets we studied, 10 (50%) are males and 10 (50%) are fema les with an average age of 23 years. The mean SBP of this volunteer tw in population was 115.18 +/- 1.27 mmHg and DBP was 68.53 +/- 1.41 mmHg . Analysis of dietary habits (vegetarian/nonvegetarian) showed that BP was greater (118.26 +/- 2.29/71.88 +/- 2.34 mmHg) in vegetarian twins than nonvegetarians (112.28 +/- 1.42/66.2 +/- 1.90 mmHg). Also a posi tive correlation between urinary excretion of calcium and BP was obser ved. The present study demonstrates that epidemiological research in a developing country like India is feasible and economical, using the t win research methodology. As observed in other populations, the major source of BP variation in the population appears to be predominantly u nder genetic control.