SERUM-LIPIDS, LIPOPROTEINS, AND LIPID METABOLIZING ENZYMES IN IDENTICAL-TWINS DISCORDANT FOR OBESITY

Obesity is associated with adverse changes in plasma lipoprotein metab olism, but it is not known completely how this association is modified by genetic factors. We assessed the contribution of obesity to serum lipid and lipoprotein levels and lipid metabolizing enzyme activities by examining 23 identical twin pairs (9 male, 14 female) who had, on t he average, an 18-kg intrapair difference in BW. Compared with lean co -twins, obese co-twins had approximately 20% higher low-density lipopr otein (LDL) cholesterol (P < 0.01), 20% lower high-density lipoprotein (2) cholesterol (P = 0.010), and 90% (men) or 35% (women) higher (P le ss than or equal to 0.06) total, very-low-density lipoprotein and LDL triglycerides. The pairs were divided into subgroups by the gender-spe cific median value of abdominal visceral fat (AVP) area the obese co-t win and by apolipoprotein E 4 phenotype. The intrapair differences in serum cholesterol fractions were similar in twin pairs with high or lo w AVF, whereas only high AVF pairs showed significant differences in t riglyceride fractions. The greatest intrapair differences in total, ve ry-low-density lipoprotein and LDL triglycerides were observed in apol ipoprotein E 4-positive pairs expressing high AVF. Compared with lean co-twins, lecithin cholesterol acyltransferase activity was 18% higher (P < 0.001) and hepatic lipase activity was 38% higher (P = 0.016) in obese co-twins with high AVF. When genetic factors are identical, obe sity is associated with an atherogenic lipid profile, especially in su bjects with high visceral fat accumulation.