Apolipoprotein E polymorphisms and mercury concentrations in pregnant women from Croatian coastal region

摘要

Apolipoprotein E (apo E, gene APOE) is a plasma glycoprotein with central roles in lipid and neuronal metabolism. Some researchers point on its metal-binding and antioxidative properties. It has three major isoforms apo E2, apo E3, and apo E4 encoded by alleles ε2, ε3, and ε4 respectively. According to some studies, individuals with ε4 variant are supposed to be more susceptible to metal toxicity, including mercury (Hg). On the other hand, it is believed that apo E is associated with higher levels of cholesterol, vitamin D and calcium, which can be beneficial early in life. The purpose of present study was to estimate relations between APOE polymorphisms and concentrations of total Hg (tHg) and methyl Hg (MeHg) in pregnant females exposed to Hg through seafood consumption. Study database consisted of tHg levels in maternal hair, urine, milk, peripheral and cord blood, and questionnaires with personal and life style data of 221 Croatian pregnant women. MeHg was additionaly measured by CVAFS (Tekran 2700). Archived DNA extracts from maternal leukocytes and cord tissues were genotyped using TaqMan? SNP assay for APOE rs429358 and rs7412 (Applied Biosystems). Statistics: Wilcoxon rank-sum test and multiple linear regression (STATA). EU projects: PHIME, HEALS. Mothers were divided into ε4 carriers (genotypes ε3/ε4 and ε4/ε4) and ε4 non-carriers (genotypes ε3/ε3, ε3/ε2 and ε2/ε2). We identified 17% ε4 carriers; they had higher geometrical means of tHg in maternal blood (ε4 carriers 2.6 ng/g, ε4 non-carriers 2.0 ng/g; p=0.0165) and cord blood (ε4 carriers 4.0 ng/g, ε4 non-carriers 2.7 ng/g; p=0.0128). MeHg represented about 80% of tHg. After taking into account the influence of seafood intake, parity, age, body mass index and smoking the observed higher concentrations of blood tHg or MeHg in APOE ε4 carriers were no longer significant. In conclusion, our data do not support the association of APOE genotypes with tHg neither with MeHg levels at low to moderate Hg exposure.