Apolipoprotein B genetic variability in Brazilian Indians

Three apolipoprotein B restriction fragment length polymorphisms (RFLPs) (X baI, MspI, and EcoRI) and the signal peptide insertion-deletion polymorphis m were investigated using the polymerase chain reaction in 140 individuals from 5 Brazilian Indian tribes, All studied markers were polymorphic in thi s ethnic group. The insertion allele 5'beta SP*29 at the signal peptide pre viously observed in Mexican Americans was detected in about 8% of the chrom osomes of 2 tribes (Gaviao and Zoro), therefore confirming the Amerindian o rigin of this allele. Negative linkage disequilibrium was observed between alleles at the signal peptide and the EcoRI polymorphism in all tribes. In 3 populations (Gaviao, Surui, and Zoro) a negative disequilibrium was also detected between the insertion-deletion signal peptide markers and the XbaI polymorphism In the whole sample of Amerindians 14 of the 24 (58%) possibl e 4-marker extended haplotypes were identified, but only haplotype 2 (5'bet a SP*24/*X+/*M+/*E+) and haplotype 5 (5'beta SP*27/*X-/*M+/*E+) were shared by all tribes. No associations between plasma lipid levels or body mass in dex and these polymorphisms were observed in this sample.