Interaction of alcohol and the G to A substitution at the promoter region of the apolipoprotein AI gene in determining plasma apolipoprotein AI levels in Yi and Han Chinese

Objective To investigate the influence on plasma lipid levels of alcohol an d a common polymorphism in the human apolipoprotein Al gene promoter at a p osition 75 bp upstream of the transcription start site. Methods For this study, 742 healthy Yi and Han subjects all above 15 years old formed the total population which was divided into three groups: the Yi -farmer group, the Yi-emigrant group and the Han-resident group. All estima tes of plasma lipids and apolipoproteins were performed using an auto-analy zer. Genetic DNA was prepared from the blood clots using the Triton X-100 l ysis technique. Amplification of a 432 bp fragment of the apoAl gene promot er was performed using PCR followed by restriction digestion, electrophores is and identification of the genotypes involved. Results The samples were divided on the basis of alcohol consumption: non-d rinkers, 1 - 25 g/day, 26 - 75 g/day and > 75 g/day. Comparing the four alc ohol consumption groups, plasma HDLC and apoAl levels were increased as the alcohol consumption increased with no evidence of threshold effects in the Yi-farmers and the Han people groups. A similar association was found in t he Yi-emigrant group, but was not statistically significant. The frequencie s of the A allele in the three populations were similar, and no significant difference of lipid and apolipoprotein levels was found between subjects w ith and without the A allele in the three populations. But, in Han and Yi-e migrant samples, the drinkers with the GG genotype had higher plasma HDLC a nd apoAl levels than non-drinkers with the same genotype, while the drinker s with the A allele had lower plasma HDLC and apoAl levels than drinkers wi thout the A allele. Nondrinkers with the A allele had higher levels of apoA l than non-drinkers with GG genotypes. It was estimated that 18% of the var iability of plasma apoAl level could be explained by the G to A polymorphis m in non-drinkers of Yi-emigrants ( F = 8.94, P < 0.01). Conclusions The present data suggest that moderate alcohol consumption and the G to A substitution could lower the risk of coronary heart disease (CHD ), but the beneficial effects of one will be negated by the other.