Apolipoprotein B gene haplotypes. Association between Ag and DNA polymorphisms.

Area of Science:

• Genetics
• Molecular Biology
• Biochemistry

Background:

• Previous studies linked the apolipoprotein B (apo B) gene Xba I polymorphism to Ag(x/y) immunochemical types and elevated serum lipoprotein levels.
• Further research indicated the same Xba I polymorphism is associated with the Ag(c/g) immunochemical polymorphism.

Purpose of the Study:

• To extend and clarify the association between the apo B gene Xba I polymorphism and Ag immunochemical polymorphisms.
• To identify major apo B haplotypes in human populations for future correlation studies with lipid levels and atherosclerosis.

Main Methods:

• Determined Ag and Xba I polymorphism in 106 individuals.
• Analyzed linkage disequilibrium between the Xba I restriction fragment length polymorphism and Ag(x/y) and Ag(c/g) loci.
• Determined apo B haplotypes for 128 alleles in homozygous individuals.

Main Results:

• The Xba I polymorphism was found to be in linkage disequilibrium with both Ag(x/y) and Ag(c/g) loci.
• All Xba I(X1/X1) genotypes were Ag(y/y), and most Xba I(X2/X2) genotypes were Ag(g/g).
• Four major apo B haplotypes were identified in the studied subpopulation.

Conclusions:

• The Xba I polymorphism is strongly associated with Ag(x/y) and Ag(c/g) loci.
• Identification of major apo B haplotypes simplifies the search for correlations between apo B alleles and lipid levels/atherosclerosis.
• This linkage provides a basis for further genetic studies on cardiovascular disease risk factors.