Analysis of the Potential Role of Apolipoprotein E Polymorphism in Genetic Predisposition to Spontaneous Abortion

Selected Genetic Characteristics of the Vietnamese Minority Living in the Czech Republic

The aim of this study was to analyse the allelic distribution of selected genes in the Czech and Vietnamese populations. We analysed samples from 94 Vietnamese volunteers and 2,859 Czech population-based subjects (2,559 from the Czechs post-MONICA and 300 volunteers from the South region of the Czech Republic). There were significant differences between the two populations for most, but not all, of the SNPs analysed. In particular, the prevalence of risk alleles in the analysed polymorphisms tended to be lower in the Vietnamese community compared to the Czech population, especially within the FTO (rs17817449; associated with obesity risk, P < 0.0001), TCF7L2 (rs7903146; linked to type 2 dia-betes, P < 0.0001) and ADH1B (rs1229984; related to alcohol consumption, P < 0.0001) genes. The genotype within the MCM6/LCT cluster (rs4988235) associated with lactase persistence was not present in the Vietnamese population. Slight genotype differences were detected for one HFE polymorphism (rs1799945 with P = 0.005; but not for rs1800562). Only the genotype frequencies within the MC4R and APOE genes were almost identical in both populations. We conclude that the Vietnamese population may have a lower genetic predisposition to the non-communicable diseases such as obesity or diabetes mellitus.

Apolipoprotein-ε4 is associated with higher fecundity in a natural fertility population

In many populations, the apolipoprotein-ε4 (APOE-ε4) allele increases the risk for several chronic diseases of aging, including dementia and cardiovascular disease; despite these harmful effects at later ages, the APOE-ε4 allele remains prevalent. We assess the impact of APOE-ε4 on fertility and its proximate determinants (age at first reproduction, interbirth interval) among the Tsimane, a natural fertility population of forager-horticulturalists. Among 795 women aged 13 to 90 (20% APOE-ε4 carriers), those with at least one APOE-ε4 allele had 0.3 to 0.5 more children than (ε3/ε3) homozygotes, while those with two APOE-ε4 alleles gave birth to 1.4 to 2.1 more children. APOE-ε4 carriers achieve higher fertility by beginning reproduction 0.8 years earlier and having a 0.23-year shorter interbirth interval. Our findings add to a growing body of literature suggesting a need for studies of populations living in ancestrally relevant environments to assess how alleles that are deleterious in sedentary urban environments may have been maintained by selection throughout human evolutionary history.

The role of connexin 37 polymorphism in spontaneous abortion

Among unique cardiovascular risk factors in women are complications during pregnancy, including miscarriage. Important risk factor is also genetic background. One of powerful candidate genes for cardiovascular disease of atherosclerotic origin (aCVD) is gene for connexin 37 (Cx37) with strong gene-environment interaction including smoking status, that is also strong risk factor for complications in pregnancy including spontaneous abortion (SA). We analyzed association between SA and Cx37 gene polymorphism (1019C>T; Pro319Ser) in 547 fetuses and its potential interaction with smoking status of mothers. Using genetic analyses from women from general population as controls, ORs for T allele, found in our previous studies to be protective against aCVD, were calculated. T allele carriers (fetuses), had OR 0.91 (95 % CI 0.72-1.14) and no interaction with smoking was observed. In conclusion, no significant association between Cx37 polymorphism and SA was observed and no modifying effect of smoking status on this association was detected.

Comparison of two groups for the apolipoprotein E polymorphisms by using next generation sequencing: The first group with three consecutive abortions and the second group with at most one abortion in three consecutive pregnancies

The importance of apolipoprotein E genotypes and allelic polymorphisms in the etiology of recurrent miscarriage is controversial. We plan to investigate this in a two-group study involving more than a thousand participants. In total, 1046 subjects (802 participants in the first group, 244 participants in the second group) were investigated. Women in the first group had a history of ≥3 consecutive spontaneous miscarriage and women in the second group had at most one miscarriage in three consecutive pregnancies. The participants with the following evidence and symptoms were excluded from both groups; structural uterine abnormality, chrosomal abnormalities and polymorphisms, hormonal imbalance, anti-nuclear antibodies, anti-phospholipid antibodies, lupus anticoagulant and homozygous genotype for FV-Leiden, MTHFR C677T, MTHFR A1298C, prothrombin 20210G>A and plasminogen activator inhibitor 4G/5G polymorphisms. We found similar apolipoprotein E allelic frequencies and genotype distributions in both groups. The frequencies of ε2 alleles were 4.1% in the first group and 2.9% in the second group, whereas those of ε3 alleles were 90.8% and 93% in the first group and the second group, respectively and ε4 alleles were 5.1% in the first group and 4.1% in the second group. The genotypes of Apo E observed in the first and the second group respectively were as follows; ε2/ε3 (7.5% and 5.7%), ε3/ε3 (82.7% and 86.5%), ε3/ε4 (8.7% and 7.4%), ε4/ε4 (0.5% and 0.4%) and ε2/ε4 (0.6% and 0). Our data did not support a possible association between apolipoprotein E genotypes and allelic frequencies, and recurrent miscarriages. We believe that the studies excluding the etiological factors that were previously found to be related with any condition are more valuable in the scope of showing the cause-effect relationship.

First Bosnian Study of the Relationship between APOE rs7412 and rs429358 Variants and Pregnancy Loss

Due to inconsistent results of APOE variants in the survival of pregnancy we investigated the potential relationship of APOE rs7412 and rs429358 with pregnancy loss (PL) in Bosnian women. We enrolled 154 women with PL. The minimum week of miscarriage was 6, while the maximum was 28. As a control group, an equal number of mothers with at least one live-born child was included. All women were recruited from the Institution of Health Protection of Women and Motherhood in Sarajevo, Bosnia and Herzegovina. Genotyping was performed by real- time PCR at the Department of General Pharmacology and Pharmacoeconomics, Pomeranian Medical University. The prevalence of genotypes E2/E3, E2/E4, E3/E3, E3/E4, E4/E4 in the group with and without PL were: 14.3 %, 1.3 %, 70.8 %, 12.3 %, 1.3 %, and 13.6 %, 1.3 %, 70.1 %, 14.3 %, 0.7 %, respectively. The frequency of the E4/E4 genotype in women with 1-2 and 3-4 PL compared to women without PL did not differ significantly between those three groups (P value = 0.0712). The frequencies of alleles ԑ2, ԑ3, ԑ4 in the group with and without PL were: 6.8 %, 85.1 %, 8.1 % and 7.5 %, 84.1 %, 8.4 %, respectively, and did not differ significantly. We conclude that our study does not confirm rs7412 and rs429358 as a potential risk factor for PL in the studied group. To elucidate the relationship between PL and variants of the APOE gene, studies with a larger sample size and placental histomorphology and genetic diagnosis are required.

Interaction of apolipoprotein E gene polymorphisms on miscarriage risk in black and white American women

OBJECTIVE

To evaluate whether [1] apolipoprotein E (APOE) polymorphisms can differentially regulate miscarriage risk and [2] whether this genotype effect could also be modulated by the race within populations.

DESIGN

Data were derived from the Coronary Artery Risk Development in Young Adults (CARDIA), a longitudinal study with black and white participants from four U.S.

SETTING

Not applicable.

PATIENT(S)

Women without miscarriages (controls) and women who miscarried at least once (cases).

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

A group of women (n = 1,372) successfully followed for 25 years and with their APOE alleles identified were analyzed for miscarriage risk throughout their reproductive life. Additionally, a larger longitudinal analysis encompassing all the participants who had their APOE characterized (n = 2,140) was also performed for the association between APOE and miscarriage risk.

RESULT(S)

In white women followed up for 25 years, the odds ratio for miscarriage associated with APOE*2 allele presence was 1.61 (95% confidence interval, 1.04-2.50) compared with APOE*33 carriers. This was a race-dependent phenomenon as no associations between APOE alleles and miscarriage was observed in black women. Likewise, Cox regression analysis showed that cumulative miscarriage risk in white women was 37.2% in the APOE*2 carriers compared with 27.8% and 24.8% in APOE*33 and APOE*4 carriers, respectively. With APOE*33 as the reference, the age-adjusted hazard ratio associated with carrying the APOE*2 allele was 1.47 (95 confidence interval, 1.06-2.05).

CONCLUSION(S)

This variable miscarriage risk, produced by an interaction between genotype and race, may reconcile, at least partially, the conflicting reports of the association of APOE and miscarriage risk.

Apolipoprotein E (Apo E) gene polymorphisms and recurrent pregnancy loss: a meta-analysis

BACKGROUND

Recently, a relationship between recurrent pregnancy loss (RPL) and Apolipoprotein E (Apo E) gene polymorphisms has been proposed. In order to investigate the real association between Apo E polymorphisms and RPL, our meta-analysis was carried out.

METHODS

We estimated the association with RPL risk under dominant and recessive models, in combination with the OR and RR with a 95% confidence interval (CI), which was used to assess the association between RPL and Apo E polymorphisms.

RESULTS

According to our criterion, there were 6 studies included. The dominant model used the E4/E3 group and the OR was 1.919 (95 %CI: 1.016-3.625, I(2) = 53.8%), the RR was 1.308 (95%Cl: 1.071-1.598) suggesting that carriers of the E4 allele would have a higher risk of causing spontaneous miscarriages. In addition, the OR was 0.727 (95%CI: 0.566-0.932, I(2) = 0.0%) and RR was 0.923 (95%CI: 0.867-0.982) in a fixed model for E3/E3 homozygotes versus other genotypes, suggesting that the Apo E3 polymorphism could be a protective factor. The OR was 1.365 (95% CI: 1.029-1.811, I(2) = 0 .0%) in a fixed model comparing the E2 allele with the E3 allele, suggesting that Apo E2 polymorphisms may contribute to RPL as a risk factor. Furthermore, after conducting sensitivity analysis in the E4/E3 group, the results showed this to be consistent and the OR was 2.249 (95%CI: 1.474-3.431).

CONCLUSIONS

There is a close association between RPL and Apo E gene polymorphisms. For RPL, the Apo E4 polymorphism could be a risk factor, the Apo E3 polymorphism may be a protective factor and the Apo E2 polymorphism may be another potential risk factor.