Low birth weight, apolipoprotein B Xba I polymorphism and hypercholesterolemia in childhood.

BACKGROUND

Xba I polymorphism in the apolipoprotein (apo) B gene has often been studied in connection with myocardial infarction, coronary artery disease and plasma lipid concentrations. The X2 allele (restriction site present) is often mentioned as a disadvantageous one. Low birth weight has also been described as a risk factor for hyperlipidemia.

OBJECTIVE

To study the Xba I polymorphism in the apo B gene.

PATIENTS AND METHODS

Southern blot or polymerase chain reaction was used in two groups of children (low and high cholesterolemic, 82 and 86 children, respectively), selected from 2000 children with known birth weight.

RESULTS

In the subgroup of high cholesterolemic children with birth weight under 3.00 kg, the X1/X1 (P=0.056) genotype was found at a lower frequency. No similar association was shown in low cholesterolemic children.

CONCLUSION

Xba I polymorphism is in a strong linkage disequilibrium with Ala (591) --> Val polymorphism in apo B, which influences postprandial lipemia and so, possibly, intrauterine nutrition and, consequently, birth weight. These results suggest that, in lower birth weight probands, X1/X1 homozygosity of Xba I polymorphism in the apo B gene may protect against the development of hypercholesterolemia, at least in childhood.