Familial aggregation and heritability for cardiovascular risk factors: a family based study in Punjab, India

Background: It is well established that the people with elevated SBP, DBP, BMI and WHR are more prone to cardiovascular disease. However, very few studies have focused on the amount of familial aggregation and heritability of these cardiovascular risk factors in Indian population. Therefore, purpose of this study was to investigate the familial aggregation of blood pressures with respect to certain anthropometric traits and to determine the relative roles of heredity in the etiology of SBP and DBP in a sample of families with three generations. Methods: The study has been conducted through house to house family study among three generations such as offspring, parent and grandparent in a scheduled caste community (Ramdasia) in Punjab. A total of 1400 individuals, constituting 380 families were surveyed for blood pressure, pulse rate, pulse pressure and anthropometric measurements to study familial aggregation and heritability for cardiovascular risk factors. The analysis represents a multivariate model which includes the each individual family data for estimation of familial correlation and heritability. Results: All risk factors showed positive familial correlation but magnitudes are different in various pairs of combination. Correlations generally are higher among genetically close relatives such as brother-sisters or parent-offspring and are lower among spouses. The estimated heritabilities were 22% for systolic and 27% for diastolic blood pressure, 19% for BMI and 17% for WHR. Conclusions: These results indicate a strong familial aggregation of cardiovascular risk factors such as SBP and DBP in this population and also showed that this familial influence can be detected from anthropometric measurements and genetic closeness. Almost all anthropometric variables were found to be significant with blood pressures among three generations.