Angiogenesis and oxidative stress-related gene variants in recurrent pregnancy loss

Recurrent pregnancy loss (RPL) affects ~3-5% of couples attempting to conceive and in around 50% of cases the aetiology remains unknown. Adequate vascularisation and placental circulation are indispensable for the development of a normal pregnancy. Prostaglandin-endoperoxide synthase 2 (PTGS2), vascular endothelial growth factor (VEGF) and the nitric oxide (NO) systems play important roles in reproductive physiology, participating in several steps including implantation and apoptosis of trophoblast cells. In this study we evaluated genetic polymorphisms in the inducible nitric oxide synthase (NOS2), PTGS2 and VEGFA genes as susceptibility factors for RPL. A case-control study was conducted in 149 women having two or more miscarriages and 208 controls. Allele and genotype distributions of the polymorphisms studied in the two groups were not statistically different. However, the dominant model showed that the presence of variant T (TT/GT) of rs2779249 (-1290G>T) of NOS2 was significantly associated with RPL (OR=1.58, CI 95%=1.03-2.44; P=0.037). The increased risk remained significant when adjusted for number of pregnancies, alcohol consumption and ethnicity (OR=1.92, CI95%=1.18-3.11; P=0.008). These results suggest that the variant genotypes of the functional polymorphism rs2779249 in the NOS2 promoter are a potential risk for RPL, possibly due to oxidative stress mechanisms.

Association between occupational exposure to benzene and chromosomal alterations in lymphocytes of Brazilian petrochemical workers removed from exposure

We aimed to investigate the association between chronic exposure to benzene and genotoxicity in the lymphocytes of workers removed from exposure. The study included 20 workers with hematological disorders who had previously worked in the petrochemical industry of Salvador, Bahia, Brazil; 16 workers without occupational exposure to benzene served as the control group. Chromosomal analysis was performed on lymphocytes from peripheral blood, to assess chromosomal breaks and gaps and to identify aneuploidy. The Kruskal-Wallis test was used to compare the mean values between two groups, and Student's t test for comparison of two independent means. The frequency of gaps was statistically higher in and the exposed group than in the controls (2.13 ± 2.86 vs. 0.97 ± 1.27, p = 0.001). The frequency of chromosomal breaks was significantly higher among cases (0.21 ± 0.58) than among controls (0.12 ± 0.4) (p = 0.0002). An association was observed between chromosomal gaps and breaks and occupational exposure to benzene. Our study showed that even when removed from exposure for several years, workers still demonstrated genotoxic damage. Studies are still needed to clarify the long-term genotoxic potential of benzene after removal from exposure.

Chromosomal abnormalities in couples with recurrent first trimester abortions

PURPOSE

To investigate the prevalence of chromosomal abnormalities in couples with two or more recurrent first trimester miscarriages of unknown cause.

METHODS

The study was conducted on 151 women and 94 partners who had an obstetrical history of two or more consecutive first trimester abortions (1-12 weeks of gestation). The controls were 100 healthy women without a history of pregnancy loss. Chromosomal analysis was performed on peripheral blood lymphocytes cultured for 72 hours, using Trypsin-Giemsa (GTG) banding. In all cases, at least 30 metaphases were analyzed and 2 karyotypes were prepared, using light microscopy. The statistical analysis was performed using the Student t-test for normally distributed data and the Mann-Whitney test for non-parametric data. The Kruskal-Wallis test or Analysis of Variance was used to compare the mean values between three or more groups. The software used was Statistical Package for the Social Sciences (SPSS), version 17.0.

RESULTS

The frequency of chromosomal abnormalities in women with recurrent miscarriages was 7.3%, including 4.7% with X-chromosome mosaicism, 2% with reciprocal translocations and 0.6% with Robertsonian translocations. A total of 2.1% of the partners of women with recurrent miscarriages had chromosomal abnormalities, including 1% with X-chromosome mosaicism and 1% with inversions. Among the controls, 1% had mosaicism.

CONCLUSION

An association between chromosomal abnormalities and recurrent miscarriage in the first trimester of pregnancy (OR=7.7; 95%CI 1.2--170.5) was observed in the present study. Etiologic identification of genetic factors represents important clinical information for genetic counseling and orientation of the couple about the risk for future pregnancies and decreases the number of investigations needed to elucidate the possible causes of miscarriages.

p53 signaling pathway polymorphisms associated to recurrent pregnancy loss

The p53 protein is known for performing essential functions in the maintenance of genomic stability in somatic cells and prevention of tumor formation. Studies of the p53 signaling pathway have suggested associations between some polymorphisms and infertility, post-in vitro fertilization implantation failure and recurrent abortions. The TP53 Pro72Arg polymorphism has been implicated as a risk factor for recurrent pregnancy loss (RPL); however, the association is controversial. In this study, our objective was to evaluate selected polymorphisms in genes of the p53 signalling pathway [TP53 c.215G>C (Pro72Arg), MDM2 c.14+309T>G (SNP309) and LIF c.1414T>G in the region 3' UTR] and determine their effect as risk factors for RPL. In a case-control study, we investigated 120 women with two or more pregnancy losses and 143 fertile control women reporting at least two live births and no history of pregnancy loss. When analyzed separately, the allele and genotype distributions of the polymorphisms in the two groups were not different. However, in a multivariate analysis adjusted for alcohol consumption, smoking, ethnicity, and number of pregnancies, the interaction between the genotypes TP53 Arg/Arg (rs1042522) and MDM2 TT (rs2279744) showed to be associated to RPL, increasing the risk for this condition (OR = 2.58, 95% CI: 1.31-5.07, p = 0.006). In conclusion, our study indicates that the combination of TP53 Arg/Arg (rs1042522) and MDM2 TT (rs2279744) genotypes may be a risk factor for RPL.