CARRIERSHIP OF THE VARIANT ALLELES OF APOE (E2, E4) MAY BE ASSOCIATED WITH GENDER-DEPENDENT MODULATION OF THE RISK FOR CEREBROVASCULAR INCIDENTS IN THE BULGARIAN POPULATION

Apolipoprotein E (APOE) is a plasma protein involved in lipid transport. At least six variant alleles of APOE gene are known to date. Three of these, namely, the alleles E2, E3 and E4 are common in all populations. There have been numerous reports suggesting that the risk for vascular disease may be increased in E4 allele carriers (probably because of the association of E4 with higher plasma cholesterol levels) whereas the effect of carriership of the E2 allele on the phenotype is less well studied. Carriership of a single E4 allele of the APOE gene appears not to have significant effect on the risk for cerebrovascular incidents in female carriers but may weakly increase the risk for male E4 carriers. Heterozygous carriership of the E2 allele may be associated with decreased risk for cerebrovascular incidents in the Bulgarian population, again in a gender-dependent fashion (more pronounced protective effect in male but not in female carriers). These effects may be related to the modulating effect of APOE variants on the levels of total and LDL cholesterol.