LACK OF INFLUENCE OF APOLIPOPROTEIN E4 ON LIPOPROTEIN LEVELS IN THE ISLAND POPULATION OF SARDINIA

Background In this study, the apolipoprotein E (apoE) genotypes as wel l as plasma lipid and lipoprotein levels have been determined for the first time in 633 healthy and unrelated inhabitants on the island of S ardinia (291 men and 342 women: agr range 6-89 years'), randomly selec ted in the four districts of Sardinia among healthy people having pare nts and grandparents born in the same geographic area. This island lie s in the centre of the western Mediterranean sea with a well-recognize d peculiar and preserved genetic background. The epsilon 3 allele freq uency (0.897) is higher than that previously reported in southern and mainland Italy and is one of the highest in Europe and among Caucasian s; epsilon 2 allele frequency (0.040) is the lowest in Europe; epsilon 4 (0.063) is unusually low and, most interestingly, does nor change i n the different age groups, i.e. does not decrease in old subjects. Re sults Lipid and lipoprotein analysis confirm that total cholesterol an d low-density lipoprotein (LDL)-cholesterol levels are lower than thos e described in mainland Italy; moreover, in this large Sardinian serie s, accurately selected, epsilon 4 allele did not influence total chole sterol (P = 0.270), LDL-cholesterol (P = 0.667) and high-density lipop rotein (HDL)-cholesterol (P = 0.549) as in other populations. In contr ast, subjects carrying the epsilon 2 allele were found to have signifi cantly lon er total cholesterol (P = 0.001) and LDL cholesterol (P = 0 .001) levels than epsilon 3 carriers. Conclusion The low epsilon 4 fre quency and the lack of influence of this allele on lipid metabolism is a unique characteristic and,,ro date, has been described only in Sard inia among Caucasians; it might contribute to the low prevalence of co ronary artery disease in this island.