Interleukin-18 gene promoter polymorphisms and recurrent spontaneous abortion.

BACKGROUND: IL-18 is a multifunctional cytokine capable of inducing either Th1 or Th2 polarization depending on the immunologic milieu. IL-18 is detected at the materno-fetal interface very soon in early pregnancy. Two polymorphisms in the promoter region of the IL-18 gene at positions of -607 and -137 appear to have functional impacts. OBJECTIVE: This study attempts to evaluate the frequency of these two polymorphisms in the IL-18 gene promoter in patients with recurrent spontaneous abortion (RSA) and normal pregnant women. SUBJECTS AND METHODS: One hundred and two RSA patients and 103 healthy pregnant women were enrolled in this study. Single nucleotide polymorphisms of the IL-18 gene at positions -607 (C/A) and -137 (G/C) were analyzed by the sequence-specific PCR method. RESULTS: There was no significant association between the allele, genotype, and haplotype frequencies of the two single nucleotide polymorphisms (SNPs) in the IL-18 gene promoter and RSA. CONCLUSION: The results of this study showed that IL-18 gene promoter polymorphisms at positions -607 and -137 did not confer susceptibility to RSA in southern Iranian patients.

Lack of association between the TGF-beta1 gene polymorphisms and recurrent spontaneous abortion.

Transforming growth factor-beta1 (TGF-beta1) is produced by T regulatory lymphocytes (Treg), which play an important role in the physiology of pregnancy. Several polymorphisms of the TGF-beta1 gene (TGFB1) have been reported, some with an important correlation with TGF-beta1 production and disease severity. We performed an association study between TGFB1 polymorphisms and recurrent spontaneous abortion (RSA). We first used a PCR-RFLP method to detect three known TGFB1 cSNPs (coding single nucleotide polymorphisms) among 111 RSA and 110 normal control women from Southern Iran, such as 29T-->C (Leu 10 Pro), 74G-->C (Arg 25 Pro) and 788C-->T (Thr 263Ile), and compared their frequencies between the two groups of subjects. To confirm results of the RFLP study and to identify new SNPs in the RSA women, we then sequenced their DNA samples for seven exons and adjacent intronic regions of TGFB1. Consequently, 10 SNPs were detected; one (-14G-->A) was located in the upstream region of exon 1, three in exons (two in exon 1 and one in exon 5) and six in intronic regions. Two (IVS5+18G-->C and IVS6+910G-->A) of the 10 SNPs were novel. Statistical analysis on the frequency of six most frequent SNPs, including the three cSNPs, as well as on the frequencies of genotypes and 13 haplotypes regarding the 6 SNPs, revealed no significant difference between RSA and control women. Therefore, this study concludes that there is no association between exonic and adjacent intronic polymorphisms of TGFB1 and RSA.

The promoter region (-800, -509) polymorphisms of transforming growth factor-beta1 (TGF-beta1) gene and recurrent spontaneous abortion.

Recurrent spontaneous abortion (RSA) is regarded as a common pregnancy complication in southern Iran. The exact causes of RSA are not yet known. Transforming growth factor-beta1 (TGF-beta1) is produced by T regulatory lymphocytes (Treg), which play an important role in the physiology of pregnancy. Several polymorphisms of the TGF-beta1 gene have been reported, some with important correlation with disease severity. In this investigation, the polymorphism of the TGF-beta1 gene at promoter region positions -800 (G/A) and -509 (C/T) was studied in 111 RSA and 110 normal female subjects from southern Iran by PCR-RFLP. Results indicated that at position -800 (G/A) polymorphism, 75.7% of RSA cases and 77.3% of normals were homozygote GG. In addition, 23.4% of cases and 22.7% of normal individuals were heterozygote AG. Only one of the patients appeared to be homozygote AA. None of the normal individuals were found to be homozygote AA at this position. In the case of the -509 (C/T) polymorphism, 38.7% of patients and 28.2% of controls were homozygote CC. While 40.6% of cases and 50.9% of normal individuals were heterozygote CT, 20.7% of RSA cases and 20.9% of controls were homozygote TT. The results indicate that there are no statistically significant differences of genotype distribution and allele frequency between RSA cases and controls at both polymorphic sites. In conclusion, the promoter region polymorphisms of TGF-beta1 at positions -800 (G/A) and -509 (C/T) may not be associated with RSA.

Promoter region polymorphisms in the transforming growth factor beta-1 (TGFß1) gene and serum TGFß1 concentration in preeclamptic and control Iranian women.

Preeclampsia (PE) is a pregnancy associated disorder characterized by hypertension and proteinuria, which causes neonatal and maternal morbidity and mortality. The Th1/Th2 cytokine paradigm of the immune adaptation in pregnancy is now expanded to include Th1/Th2/Th17 and regulatory T (Treg) cells. Among cytokines, TGFß1 has properties that justify evaluation of its role in PE etiopathology. In this investigation the polymorphisms of the TGFß1 gene at promoter region, positions -800G→A and -509C→T, were studied in 142 PE and 140 normal pregnant female subjects using PCR-RFLP. Additionally, serum TGFß1 was determined by ELISA. At position -800G→A genotypes and allele frequencies showed no significant differences between PE patients (GG 73.9%; GA 21.1%; AA 4.93%) and normal control (GG 70%; GA 28.6%; AA 1.4%) women. However the AA genotype at this position was more frequent in PE patients than in the control group. At -509C→T position, genotypes and allele frequencies showed no significant differences between PE patients and control individuals. The CC genotype at -509C→T position was more prevalent in PE patients than in the control group. The mean serum TGFß1 level was significantly higher (62.14 ng/ml) in PE patients compared with pregnant and non-pregnant control groups (and 47.01 and 40.68 ng/ml, respectively). In conclusion, the promoter region polymorphisms of TGFß1 may not be associated with PE, but serum levels of this cytokine may contribute to the etiopathology of PE.

Coding region polymorphisms in the indoleamine 2,3-dioxygenase (INDO) gene and recurrent spontaneous abortion.

Indoleamine 2,3-dioxygenase (INDO) catalyzes degradation of the indole ring of indoleamines and locally depletes tryptophan. INDO expression suppresses T cell proliferation and activation. Genetic variation in the INDO gene may contribute to the variable INDO enzyme expression, activity and severity of some diseases. Recurrent spontaneous abortion (RSA) is a common pregnancy complication and the exact causes of RSA are not yet known. We performed an association study between INDO single nucleotide polymorphisms (SNPs) and RSA. To identify INDO SNPs we sequenced DNA samples for ten exons and adjacent intronic regions from 111 RSA patients. Consequently 10 SNPs were detected; four in exons (one in exon 4, two in exon 9 and one in exon 10) and six in intronic regions (one in intron 3, three in intron 6, one in intron 8 and one in intron 9). Three (IVS3+562 del C, IVS8+116 T→G and IVS9+2431 G→A) of these ten SNPs have been registered at the NCBI SNP database. Statistical analysis of allele, genotype and haplotype frequency distribution in the three most frequent SNPs (IVS3+562 del C, IVS6+61 G→A and IVS9+2431 G→A) showed no significant differences between the 111 RSA and 105 matched control women. CGA and CGG were the most frequent haplotypes in both the RSA and control groups. We conclude that there is no association between INDO polymorphisms and susceptibility of Iranian women to RSA.