DNA haplotypes of the human apoprotein B gene in coronary atherosclerosis.

Haplotypes of the apoprotein B gene, localised to chromosome 2, were identified using restriction fragment length polymorphisms (RFLPs) for the enzymes XbaI and EcoRI. Four haplotypes were identified at this locus, X1R1 (H1), X1R2 (H2), X2R1 (H3) and X2R2 (H4); where the X1 and X2 alleles were characterised by gene-related fragments of 5.0 and 8.6 kb respectively and the R1 and R2 alleles by fragments of 13.0 and 11.0 kb respectively. Although the polymorphic sites are less than 10 kb apart, they were found to be in linkage equilibrium. The value of the disequilibrium parameter (D) was 0.0042, approximately 7.5% of the theoretical maximum (Dmax = 0.054). No disease association could be demonstrated between either apoB RFLP, or haplotype, and coronary athersclerosis in our population from south-east England. This was in accordance with a study of apoB RFLPs for a population from the West Coast of the United States, but in contrast to a study of an East-Coast population. There are no previous data for the association between apoB haplotypes and coronary atherosclerosis.