Evidence for genetic factors explaining the association between birth weight and low-density lipoprotein cholesterol and possible intrauterine factors influencing the association between birth weight and high-density lipoprotein cholesterol: Analysis in twins

Recent studies have demonstrated an association between low weight at birth and an atherogenic lipid profile in later life. To examine the influences of intrauterine and genetic factors, we investigated 53 dizygotic and 61 mo nozygotic adolescent twin pairs. Regression analysis demonstrated that low birth weight was associated with high levels of total cholesterol, low-dens ity lipoprotein (LDL) cholesterol and apolipoprotein B (-0.17 mmol/liter pe r kg, P = 0.07; -0.:18 mmol/liter per kg, P = 0.04; and -0.07 g/liter per k g, P = 0.02, respectively) and with low levels of high-density lipoprotein (HDL) cholesterol (+0.04 mmol/liter per kg, P = 0.1), after adjustment for age, sex, and body mass index. Intrapair differences in birth weight were s ignificantly associated with differences in total cholesterol, LDL choleste rol, and apolipoprotein B in dizygotic twins after adjustment for differenc es in current body mass index (-0.49 mmol/liter per kg, P = 0.02; -0.51 mmo l/liter per kg, P = 0.01; and -0.10 g/liter per kg, P = 0.04, respectively) , demonstrating that the larger the difference in birth weight, the higher these risk factors in the twin with the lower birth weight, compared with t he cotwin with the higher birth weight. In monozygotic twins, however, the associations between intrapair differences in birth weight and differences in total cholesterol, LDL cholesterol, and apolipoprotein B were in the opp osite direction (+0.32 mmol/liter per kg, P = 0.03; +0.23 mmol/liter per kg , P = 0.08; and +0.06 g/liter per kg, P = 0.04, respectively). The associat ion between intrapair differences in birth weight and differences in HDL ch olesterol was not significant in dizygotic twins (+0.04 mmol/liter per kg, P = 0.6) and of borderline significance in monozygotic twins (+0.11 mmol/li ter per kg, P = 0.05). These data suggest that genetic factors account for the association of low birth weight with high levels of total cholesterol, LDL cholesterol, and apolipoprotein B, whereas intrauterine factors possibl y play a role in the association between birth weight and HDL cholesterol.