[Polymorphism insertion/deletion of apolipoprotein B gene: effect on lipid levels in obese patients].

Apolipoprotein B (apoB) is the major proteic component of LDL, VLDL and chylomicrons. Numerous polymorphisms of the apolipoprotein B gene have been described. Particularly, a polymorphism of insertion/deletion located in the coding part of the signal peptide of apoB, associated with modifications of lipid concentrations and the risk of cardiovascular disease, has been reported in the general population. Since obesity is frequently associated with dyslipidemias, the aim of our study was to assess the effect of the insertion/deletion polymorphism of the apolipoprotein B gene on lipid levels in obese subjects. 234 unrelated caucasian obese subjects (74 men and 160 women, aged 39.3 +/- 10.5, BMI : 32.8 +/- 4.7) were recruited. The insertion/deletion polymorphism was determined by electrophoresis in polyacrylamide gels after PCR amplification. The relative frequencies of the Ins and Del alleles were 0.71 and 0.29 respectively. These frequencies were similar to those found in other Caucasian populations. In the whole population, individuals with the Del/Del genotype had significantly higher total-cholesterol to HDL-cholesterol ratios (p = 0.004), LDL-cholesterol to HDL-cholesterol ratios (p = 0.01) and TG-VLDL levels (p < 0.05). They also showed a tendency for higher triglyceride levels (p = 0.09) and lower HDL-cholesterol, apolipoprotein AI and LpAI levels. The allele deletion results in the absence of three amino acids (Leu-Ala-Leu) in the signal peptide of apo B. In the obese people, these structural changes may have some effect on lipid metabolism and cause variation in serum lipid concentrations. Copyright John Libbey Eurotext 20003.