Lack of influence of apolipoprotein E4 on lipoprotein levels in the island population of Sardinia

Abstract

Background: In this study, the apolipoprotein E (apoE) genotypes as well as plasma lipid and lipoprotein levels have been determined for the first time in 633 healthy and unrelated inhabitants on the island of Sardinia (291 men and 342 women, age range 6-89 years), randomly selected in the four districts of Sardinia among healthy people having parents and grandparents born in the same geographic area. This island lies in the centre of the western Mediterranean sea with a well-recognized peculiar and preserved genetic background. The epsilon 3 allele frequency (0.897) is higher than that previously reported in southern and mainland Italy and is one of the highest in Europe and among Caucasians; epsilon 2 allele frequency (0.040) is the lowest in Europe; epsilon 4 (0.063) is unusually low and, most interestingly, does not change in the different age groups, i.e. does not decrease in old subjects.

Results: Lipid and lipoprotein analysis confirm that total cholesterol and low-density lipoprotein (LDL)-cholesterol levels are lower than those described in mainland Italy; moreover, in this large Sardinian series, accurately selected, epsilon 4 allele did not influence total cholesterol (P = 0.270), LDL-cholesterol (P = 0.667) and high-density lipoprotein (HDL)-cholesterol (P = 0.549) as in other populations. In contrast, subjects carrying the epsilon 2 allele were found to have significantly lower total cholesterol (P = 0.001) and LDL-cholesterol (P = 0.001) levels than epsilon 3 carriers.

Conclusion: The low epsilon 4 frequency and the lack of influence of this allele on lipid metabolism is a unique characteristic and, to date, has been described only in Sardinia among Caucasians; it might contribute to the low prevalence of coronary artery disease in this island.