Moderate genetic influences on plasma levels of plasminogen activator inhibitor-1 and evidence of genetic and environmental influences shared by plasminogen activator inhibitor-1, triglycerides, and body mass index.

Both genes and environmental factors have been reported to influence plasma levels of plasminogen activator inhibitor-1 (PAI-1). However, the relative importance of genetic influences (i.e., heritability) on plasma PAI-1 levels has not yet been investigated. Furthermore, PAI-1 levels are correlated with body mass index (BMI) and triglycerides. These correlations could reflect genetic and/or environmental factors in common to PAI-1, triglycerides, and BMI. We applied multivariate genetic analysis methods to assess the relative importance of genetic and environmental influences on plasma PAI-1 levels and to test the significance of genetic and/or environmental influences shared by PAI-1, triglycerides, and BMI in 217 pairs of middle-aged and elderly twins, of whom 113 pairs were reared apart and 121 pairs were women. The heritability estimate for PAI-1 levels was 42%. Individual-specific environmental factors explained 36% of the variance for PAI-1 levels. The remaining variance of PAI-1 was explained by rearing and residual-familial environmental factors. Furthermore, a genetic correlation of 1.00 between PAI-1 and triglycerides, a rearing environmental correlation of 1.00 between PAI-1 and BMI, a residual-familial environmental correlation of 1.00 between PAI-1 and triglycerides, and a genetic correlation of 0.63 between PAI-1 and BMI, were found. In conclusion, the present results suggest that genetic influences on plasma PAI-1 are moderate. Genetic and shared rearing or residual-familial environmental factors shared by PAI-1, BMI, and triglycerides explain the phenotypic association between these measures. It appears that all the genetic influences for PAI-1 are more or less shared with those for triglycerides and BMI.