Lifestyle factors affecting intrapair differences of serum apoproteins and cholesterol concentrations in adult identical twins.

83 pairs of twins, aged 50-74 years, were studied with respect to their serum apoproteins (A-I, A-II, B, C-II, C-III and E) and cholesterol concentrations. Each of the variables showed a higher intraclass correlation in the MZ twins than in the DZ twins. HDL cholesterol showed the highest intraclass correlation among the variables and indicated strong heritability. In the MZ pairs discordant for alcohol consumption, the higher consumers within the pair showed a significantly higher level of apo A-I and HDL cholesterol, and a lower level of apo B concentration. In the MZ pairs discordant for cigarette smoking, the higher consumers within the pair showed a significantly lower level of apo C-III. In the MZ pairs discordant for obesity, the heavier twins within the pair showed higher levels of non-HDL cholesterol, total cholesterol, apo B, apo C-II and apo C-III. In the MZ pairs discordant, for occupation, the twins of 'heavy work' showed significantly higher levels of apo B, total cholesterol and non-HDL cholesterol than the twins of 'light work'.