Genetic and cultural inheritance of plasma fibrinogen concentration.

Genetic and cultural heritability of plasma fibrinogen concentration was estimated by path analysis with environmental indices in 85 families identified by means of probands with early myocardial infarction and in 85 families randomly selected from the general population. A substantial proportion of the variance of the plasma fibrinogen level, 51%, was accounted for by genetic heritability, whereas the cultural heritability was negligible. No intergenerational differences were indicated in genetic or cultural heritability. The combined effect of obesity and smoking was found to explain 3% of the variance of the plasma fibrinogen level. The demonstration of such substantial genetic control further supports the view that plasma fibrinogen is a primary risk factor for CHD rather than a reflection of the severity of manifest disease.