Fetal MMP2/MMP9 polymorphisms and intrauterine growth restriction risk

VNtyper enables accurate alignment-free genotyping of MUC1 coding VNTR using short-read sequencing data in autosomal dominant tubulointerstitial kidney disease

The human genome comprises approximately 3% of tandem repeats with variable length (VNTR), a few of which have been linked to human rare diseases. Autosomal dominant tubulointerstitial kidney disease-MUC1 (ADTKD-MUC1) is caused by specific frameshift variants in the coding VNTR of the MUC1 gene. Calling variants from VNTR using short-read sequencing (SRS) is challenging due to poor read mappability. We developed a computational pipeline, VNtyper, for reliable detection of MUC1 VNTR pathogenic variants and demonstrated its clinical utility in two distinct cohorts: (1) a historical cohort including 108 families with ADTKD and (2) a replication naive cohort comprising 2,910 patients previously tested on a panel of genes involved in monogenic renal diseases. In the historical cohort all cases known to carry pathogenic MUC1 variants were re-identified, and a new 25bp-frameshift insertion in an additional mislaid family was detected. In the replication cohort, we discovered and validated 30 new patients.

Molecular pathways of senescence regulate placental structure and function

The placenta is an autonomous organ that maintains fetal growth and development. Its multinucleated syncytiotrophoblast layer, providing fetal nourishment during gestation, exhibits characteristics of cellular senescence. We show that in human placentas from pregnancies with intrauterine growth restriction, these characteristics are decreased. To elucidate the functions of pathways regulating senescence in syncytiotrophoblast, we used dynamic contrast‐enhanced MRI in mice with attenuated senescence programs. This approach revealed an altered dynamics in placentas of p53^−/−, Cdkn2a^−/−, and Cdkn2a^−/−;p53^−/− mice, accompanied by histopathological changes in placental labyrinths. Human primary syncytiotrophoblast upregulated senescence markers and molecular pathways associated with cell‐cycle inhibition and senescence‐associated secretory phenotype. The pathways and components of the secretory phenotype were compromised in mouse placentas with attenuated senescence and in human placentas from pregnancies with intrauterine growth restriction. We propose that molecular mediators of senescence regulate placental structure and function, through both cell‐autonomous and non‐autonomous mechanisms.

TGFβ3, MSX1, and MMP3 as Candidates for NSCL±P in an Indian Population

OBJECTIVE

To evaluate the association of transforming growth factor β3 ( TGFβ3), muscle segment homeobox 1 ( MSX1), Metalloproteinases 3 ( MMP3), and MMP9 genes as candidates for nonsyndromic cleft lip and/or palate in an Indian population.

DESIGN

Case-control association study, mutational screening, and functional evaluation of obtained mutations.

SETTING

Mutational screening of the developmental genes, TGFβ3 and MSX1, along with functional evaluation and association of promoter region SNPs-one each in MMP3 and MMP9.

PATIENTS, PARTICIPANTS

Two hundred forty five NSCL±P cases from G. S. Memorial Plastic Surgery Hospital and Trauma Center, Varanasi and 201 healthy controls without a family history of congenital malformations from nearby schools, primary health centers, and the university hospital.

MAIN OUTCOME MEASURE(S)

Sequencing, SSCP, and PCR-RFLP were used for candidate gene screening. MatInspector and electrophoretic mobility shift assay (EMSA) were used to check the differential transcription factor binding of the variants at promoter region. Luciferase assay was used to test the transcriptional potential of the variant, and evaluation of the alternative splice site was carried out using exon-trapping experiment.

RESULTS

Metalloproteinases3 -1171 5A/6A was associated with NSCL±P, whereas MMP9 -1562 C/T did not show association. A rare variant in the promoter region of TGFβ3 (rs117462711) creates a differential binding site, confirmed by EMSA. Luciferase assay showed 3.7-fold increased expression level in mutant construct. A synonymous change in MSX1 (rs34165410) showed association with NSCL±P, which may create an alternative splice site or lead to low codon usage. Exon-trapping experiment failed to confirm alternative splicing, indicating low codon usage frequency of the mutant affecting the gene function.

CONCLUSIONS

TGFβ3, MSX1, and MMP3 are candidates for NSCL±P.

UNDERSTANDING THE PLACENTAL AETIOLOGY OF FETAL GROWTH RESTRICTION; COULD THIS LEAD TO PERSONALIZED MANAGEMENT STRATEGIES?

Fetal growth restriction (FGR) is defined as the failure of a fetus to attain its full genetic growth potential. It is a leading cause of stillbirth, prematurity, cerebral palsy and perinatal mortality. Small size at birth increases surviving infants’ lifelong risk of adverse health outcomes associated with the metabolic syndrome. The pathophysiology of abnormal fetal growth is extremely complex and incompletely understood, with a plethora of genetic, signalling and metabolic candidates under investigation, many of which may result in abnormal structure and function of the placenta. In contrast to, or maybe because of, the underlying complexities of FGR, the strategies clinicians have for identifying and managing this outcome are conspicuously limited. Current clinical practice is restricted to identifying pregnancies at risk of FGR, and when FGR is detected, using intensive monitoring to guide the timing of delivery to optimise fetal outcomes. Abnormal Doppler indices in the umbilical artery are strongly associated with poor perinatal outcomes and are currently the “gold standard” for clinical surveillance of the growth-restricted fetus.

Differential Expression of Matrix Metalloproteinase-9 Gene in Wounds of Type 2 Diabetes Mellitus Cases With Susceptible -1562C>T Genotypes and Wound Severity

Coordinated extracellular matrix deposition is a prerequisite for proper wound healing which is mainly orchestrated by matrix metalloproteinases (MMPs). Diabetic wounds generally show compromised wound healing cascade and abnormal MMP9 concentration is one of the cause. Our group have recently shown that the polymorphism -1562 C>T in the promoter region of MMP9 gene is associated with pathogenesis of wound healing impairment in T2DM patients. In present study we have done expression profiling of MMP9 gene in the wound biopsy of DFU cases. Expression level of MMP9 mRNA was then compared with susceptible -1562 C>T genotypes (TT and CT) as well as with different grades of wounds. We also screened the promoter region of MMP9 gene to see the methylation state of CpGs present there. Our study suggests that levels of MMP9 mRNA increase significantly with the wound grades. Moreover, the MMP9 levels in diabetic wounds were also dependent on -1562 C>T polymorphism in the promoter region of MMP9. Diabetic wounds also showed a significant unmethylated status of MMP9 promoter compared to control wounds. In conclusion, The risk genotypes of -1562 C>T polymorphism along with lack of methylation of CpG sites in MMP9 gene promoter may result in altered expression of MMP9 in wounds of T2DM cases resulting into nonhealing chronic ulcers in them.

The long non-coding RNA NEAT1 is increased in IUGR placentas, leading to potential new hypotheses of IUGR origin/development

INTRODUCTION

Intrauterine Growth Restriction (IUGR) is a multifactorial disease defined by an inability of the fetus to reach its growth potential. IUGR not only increases the risk of neonatal mortality/morbidity, but also the risk of metabolic syndrome during adulthood. Certain placental proteins have been shown to be implicated in IUGR development, such as proteins from the GH/IGF axis and angiogenesis/apoptosis processes.

METHODS

Twelve patients with term IUGR pregnancy (birth weight < 10th percentile) and 12 CTRLs were included. mRNA was extracted from the fetal part of the placenta and submitted to a subtraction method (Clontech PCR-Select cDNA Subtraction).

RESULTS

One candidate gene identified was the long non-coding RNA NEAT1 (nuclear paraspeckle assembly transcript 1). NEAT1 is the core component of a subnuclear structure called paraspeckle. This structure is responsible for the retention of hyperedited mRNAs in the nucleus. Overall, NEAT1 mRNA expression was 4.14 (±1.16)-fold increased in IUGR vs. CTRL placentas (P = 0.009). NEAT1 was exclusively localized in the nuclei of the villous trophoblasts and was expressed in more nuclei and with greater intensity in IUGR placentas than in CTRLs. PSPC1, one of the three main proteins of the paraspeckle, co-localized with NEAT1 in the villous trophoblasts. The expression of NEAT1_2 mRNA, the long isoform of NEAT1, was only modestly increased in IUGR vs. CTRL placentas.

DISCUSSION/CONCLUSION

The increase in NEAT1 and its co-localization with PSPC1 suggests an increase in paraspeckles in IUGR villous trophoblasts. This could lead to an increased retention of important mRNAs in villous trophoblasts nuclei. Given that the villous trophoblasts are crucial for the barrier function of the placenta, this could in part explain placental dysfunction in idiopathic IUGR fetuses.

A functional single nucleotide polymorphism -1562C>T in the matrix metalloproteinase-9 promoter is associated with type 2 diabetes and diabetic foot ulcers

Impaired neovascularization is the hallmark of type 2 diabetes, which results in various macro- and microvascular complications and the development of foot ulcerations later in life. Matrix metalloproteinases (MMPs) are the key enzymes which influence matrix remodeling. Here, we aim to investigate that whether single nucleotide polymorphism (SNP -1562C>T) (rs3918242) in the promoter region of MMP-9 gene, which alters the transcriptional activity of MMP-9 is associated with type 2 diabetes and diabetic foot ulcers (DFUs). This case-control study was composed of 730 individuals, out of which 463 patients were with type 2 diabetes mellitus (T2DM) and 267 were nondiabetic healthy controls (non-DM controls). T2DM patients were subclassified as 149 cases without any secondary complications (T2DMNSC), 110 with DFUs, 204 T2DM patients having one or the other secondary complications. Genotyping for -1562C>T SNP in MMP-9 gene was done by polymerase chain reaction-restriction fragment length polymorphism method and sequencing. SNP -1562C>T of MMP-9 gene showed a significant association with T2DM and DFU. The allele distribution differed significantly between patients and normal control group (odds ratio = 1.82, P = .00005, 95% confidence interval = 1.36-2.42 for T2DM vs control and odds ratio = 2.112, P = .00048, 95% confidence interval = 1.38-3.126 for DFU vs control) indicating strong association of SNP -1562C>T of MMP-9 gene with T2DM and DFU in an Indian population. SNP -1562C>T in the promoter of the MMP-9 gene results in increased expression at the level of the transcription. To the best of our knowledge, this is the first report that suggests that SNP -1562C>T in the promoter of the MMP-9 gene is associated with T2DM and DFU. An increased MMP-9 production from high expressing T allele may promote matrix degradation.

MMP-9 (-1562 C:T) polymorphism as a biomarker of susceptibility to severe pre-eclampsia

AIM

To investigate the role of MMP-9 (-1562 C:T) polymorphism as a biomarker for susceptibility to pre-eclampsia.

PATIENTS & METHODS

MMP-9 variants were detected in 160 women with mild and severe pre-eclampsia and 112 healthy pregnant women.

RESULTS

A significantly higher frequency of MMP-9 CT genotype was observed in both mild and severe pre-eclamptic women compared with controls. In the presence of CT + TT genotype the risk of severe pre-eclampsia increased 2.37-fold (p = 0.02). In women with early-onset pre-eclampsia the frequency of MMP-9 CT + TT genotype was significantly higher (p = 0.045) compared with those with late-onset pre-eclampsia.

CONCLUSION

The MMP-9 variant could be a useful biomarker of susceptibility to severe pre-eclampsia and early-onset severe pre-eclampsia.

Matrix Metalloproteinase-9 Level and Gene Polymorphism in Sleep Disordered Breathing Patients with or without Cardiovascular Disorders

OBJECTIVE

Obstructive sleep apnea syndrome (OSAS) is associated with increased cardiovascular morbidity and mortality. We aimed to investigate the matrix metalloproteinase-9 (MMP-9) level and MMP-9 gene polymorphism in sleep apnea patients with or without cardiovascular disease.

STUDY DESIGN

Case-control study.

MATERIAL AND METHODS

Two hundred nine patients [Mean age (±SD), 47 (±12) yrs; M/F, 170/39] diagnosed with sleep-disordered breathing were included in the study. Serum MMP-9 level was performed using enzyme-linked immunosorbant assay (ELISA) and MMP-9 gene polymorphism with polymerase chain reaction-restriction fragment length polymorphism. We divided the patient group into two subgroups: (1) patients with confirmed cardiovascular disease, i.e. CV-P Group and (2) patients without cardiovascular disease, CV-N Group. We compared all parameters between the two groups.

RESULTS

There were 56 OSAS patients with cardiovascular disorder (CV-positive group) and 153 OSAS patients without cardiovascular disorder (CV-negative group). CC, CT and TT genotype distributions between groups were similar [31 (55%), 25 (45%), 0 (0%) vs 88 (57%), 61 (40%), 4 (3%); respectively, p>0.05]. MMP-9 level was significantly higher in CV-P patients (442.7±139.3 pg/mL) than in CV-N patients (364.4±165.0 pg/mL; p=0.0018).

CONCLUSION

Our results showed that the presence of MMP-9 polymorphism was not associated with cardiovascular disease. MMP-9 level was higher in OSAS patients with cardiovascular disorders than without cardiovascular disorders. Finally, MMP-9 genotype was not associated with serum MMP-9 levels.

Innate immune system gene polymorphisms in maternal and child genotype and risk of preterm delivery

OBJECTIVE

There is little information about the combination of genetic variability in pregnant women and their children in relation to the risk of preterm delivery (PTD). In a sub-cohort of 487 non-Hispanic white and 288 African-American mother/child pairs, the Pregnancy Outcomes and Community Health Study assessed 10 functional polymorphisms in 9 genes involved in innate immune function.

METHODS

Race-stratified weighted logistic regression models were used to calculate odds ratios for genotype and PTD/PTD subtypes. Polymorphisms significantly associated with PTD/PTD subtypes were tested for mother/child genotype interactions.

RESULTS

Three maternal polymorphisms (IL-1 receptor antagonist intron two repeat (IL-1RN), matrix metalloproteinase- -C1562T, and TNF receptor two M196R (TNFR2)) and three child polymorphisms (IL1-RN, tumor necrosis factor-alpha -G308A, and TNFR2) were associated with PTD, but associations varied by PTD subtype and race. Two interactions were detected for maternal and child genotype. Among non-Hispanic white women, the odds of PTD was higher when both mother and child carried the IL-1RN allele two (additive interaction p < 0.05). Among African-American women, the odds of PTD were higher when both mother and child carried the TNFR2 R allele (multiplicative interaction p < 0.05).

CONCLUSION

These results highlight the importance of assessing both maternal and child genotype in relation to PTD risk.

Association between matrix metalloproteinase (MMP)-2 polymorphisms and MMP-2 levels in hypertensive disorders of pregnancy

We examined whether two functional polymorphisms (g.-1306C>T and g.-735C>T) in matrix metalloproteinase (MMP)-2 gene are associated with preeclampsia (PE) or gestational hypertension (GH), and whether they modify MMP-2 or tissue inhibitor of metalloproteinase (TIMP)-2 plasma concentrations in these hypertensive disorders of pregnancy. We studied 130 healthy pregnant (HP), 130 pregnant with GH, and 133 pregnant with PE. Genomic DNA was extracted from whole blood and genotypes for g.-1306C>T and g.-735C>T polymorphisms were determined by Real Time-PCR, using Taqman allele discrimination assays. Haplotypes were inferred using the PHASE program. Plasma MMP-2 and TIMP-2 concentrations were measured by ELISA. The main findings were that pregnant with PE have higher plasma MMP-2 and TIMP-2 concentrations than HP (P<0.05), although the MMP-2/TIMP-2 ratios were similar (P>0.05). Moreover, pregnant with GH have elevated plasma MMP-2 levels and MMP-2/TIMP-2 ratios compared to HP (P<0.05). While MMP-2 genotypes and haplotypes are not linked with hypertensive disorders of pregnancy, MMP-2 genotypes and haplotypes are associated with significant alterations in plasma MMP-2 and TIMP-2 concentrations in preeclampsia (P<0.05). Our findings may help to understand the relevance of MMP-2 and its genetic polymorphisms to the pathophysiology of hypertensive disorders of pregnancy. It is possible that patients with PE and the MMP-2 haplotype combining the C and T alleles for the g.-1306C>T and g.-735C>T polymorphisms may benefit from the use of MMPs inhibitors such as doxycycline. However, this possibility remains to be determined.

Functional SNP -1562C/T in the promoter region of MMP9 and recurrent early pregnancy loss

Angiogenesis, invasion and decidualization play an important role in uterine preparation and embryo development. Matrix metalloproteinases (MMP) are crucial for the degradation/remodelling of the extracellular matrix and are involved in spiral artery formation and invasion of endometrium during implantation. A functional single-nucleotide polymorphism (SNP) in the MMP9 promoter, 1562C/T, is known to influence expression in an allele-specific manner. The present study evaluated the association between maternal genotype of SNP 1562C/T of MMP9 and recurrent early pregnancy loss (REPL) risk. This case–control study was comprised of REPL patients (n = 106) and women having one healthy child as controls (n = 111). Genotyping for SNP 1562C/T of MMP9 was performed by PCR/restriction fragment length polymorphism followed by DNA sequencing. Allele and genotype distribution did not differ significantly between patients and controls (by allele, chi-squared 0.228, odds ratio 1.12, 95% confidence interval 0.695–1.816; by genotype, chi-squared 0.893). Thus SNP 1562C/T of MMP9 was not associated with REPL risk in this population and further study in other populations will verify whether it is associated with REPL risk or not. REPL is a multifactorial pathology and other genetic or environmental factors may be contributing to the complex aetiology of REPL.

Altered levels of insulin-like growth factor binding protein proteases in preeclampsia and intrauterine growth restriction

Intrauterine growth restriction (IUGR) and preeclampsia (PE) are leading causes of perinatal and maternal morbidity and mortality. Many studies have found association between low levels of insulin-like growth factor binding protein (IGFBP) proteases in the first trimester maternal circulation and the risk of subsequent development of PE and/or IUGR. These results are generally interpreted to reflect decreased production of the proteases by the placenta, leading to reduced proteolysis of IGFBPs and lower free levels of insulin-like growth factor (IGF), resulting in diminished feto-placental development. However, the association between low circulating levels of placental proteins early in pregnancy and the subsequent development of IUGR and/or PE could be due to low exchange in the placenta and not due to reduced production. In contrast, late in pregnancy, the circulating levels of these proteins and their expression in the placenta are often elevated in PE, which may reflect upregulation to compensate for abnormal placental development, that is an adaptive mechanism to increase IGFBP proteolysis, increase local IGF levels and promote feto-placental growth. Further research into the biological mechanisms underlying these associations will aid the identification of high-risk pregnancies and the development of therapeutic targets for diseases for which there are presently no preventative measures.

Polymorphisms in maternal and fetal genes encoding for proteins involved in extracellular matrix metabolism alter the risk for small-for-gestational-age

OBJECTIVE

To examine the association between maternal and fetal genetic variants and small-for-gestational-age (SGA).

METHODS

A case-control study was conducted in patients with SGA neonates (530 maternal and 436 fetal) and controls (599 maternal and 628 fetal); 190 candidate genes and 775 SNPs were studied. Single-locus, multi-locus and haplotype association analyses were performed on maternal and fetal data with logistic regression, multifactor dimensionality reduction (MDR) analysis, and haplotype-based association with 2 and 3 marker sliding windows, respectively. Ingenuity pathway analysis (IPA) software was used to assess pathways that associate with SGA.

RESULTS

The most significant single-locus association in maternal data was with a SNP in tissue inhibitor of metalloproteinase 2 (TIMP2) (rs2277698 OR = 1.71, 95% CI [1.26-2.32], p = 0.0006) while in the fetus it was with a SNP in fibronectin 1 isoform 3 preproprotein (FN1) (rs3796123, OR = 1.46, 95% CI [1.20-1.78], p = 0.0001). Both SNPs were adjusted for potential confounders (maternal body mass index and fetal sex). Haplotype analyses resulted in associations in α 1 type I collagen preproprotein (COL1A1, rs1007086-rs2141279-rs17639446, global p = 0.006) in mothers and FN1 (rs2304573-rs1250204-rs1250215, global p = 0.045) in fetuses. Multi-locus analyses with MDR identified a two SNP model with maternal variants collagen type V α 2 (COL5A2) and plasminogen activator urokinase (PLAU) predicting SGA outcome correctly 59% of the time (p = 0.035).

CONCLUSIONS

Genetic variants in extracellular matrix-related genes showed significant single-locus association with SGA. These data are consistent with other studies that have observed elevated circulating fibronectin concentrations in association with increased risk of SGA. The present study supports the hypothesis that DNA variants can partially explain the risk of SGA in a cohort of Hispanic women.

Matrix metalloproteinase (MMP)-9 genotypes and haplotypes in preeclampsia and gestational hypertension

BACKGROUND

Abnormal production of matrix metalloproteinases (MMPs), especially MMP-9, may play a role in hypertensive disorders of pregnancy. These alterations may result from functional genetic polymorphisms in the promoter region of MMP-9 gene, which are known to change MMP-9 expression. We examined whether 2 MMP-9 polymorphisms (C(-1562)T and (CA)n) and haplotypes are associated with preeclampsia and/or gestational hypertension.

METHODS

We studied 476 pregnant women: 176 healthy pregnant (HP), 146 pregnant with gestational hypertension (GH), and 154 pregnant with preeclampsia (PE). Genomic DNA was extracted from whole blood and genotypes for C(-1562)T and (CA)n polymorphisms were determined by PCR-RFLP. Haplotype frequencies were inferred using the PHASE ver. 2.1 program.

RESULTS

For the g.-90(CA)13-25 polymorphism, no significant differences were found in genotype and allele distributions when PE or GH groups were compared with HP group. However, the CT genotype and T allele for g.-1562C>T polymorphism were more commonly found in GH subjects compared with the HP group (both P<0.05). Conversely, we found no differences in genotypes or allele distributions for the g.-1562C>T polymorphism when the PE and the HP groups were compared. No significant differences were found in overall distributions of haplotype frequencies when the GH or the PE group was compared with the HP group.

CONCLUSIONS

The C(-1562)T polymorphism in MMP-9 gene is associated with gestational hypertension, but not with preeclampsia. These findings may help to explain the higher plasma MMP-9 levels previously reported in GH compared with HP.

MMP9 limits apoptosis and stimulates branching morphogenesis during kidney development

Early events in kidney organogenesis involve reciprocal interactions between the ureteric bud and the metanephric mesenchyme, which lead to remodeling of the extracellular matrix. This remodeling involves matrix metalloproteases (MMPs), but the specific roles of individual MMPs in kidney development are not completely understood. Here, we analyzed MMP9-deficient mice at the first step of kidney development and found that MMP9 deficiency delayed embryonic kidney maturation and increased apoptosis ex vivo by 2.5-fold. These early defects resulted in a 30% decrease in nephron number, a 20% decrease in adult kidney weight, and altered kidney function and morphology at 12 mo. The membrane form of stem cell factor (SCF) increased, whereas the activated form of the SCF receptor, c-kit, decreased in MMP9-deficient embryonic kidneys. In organotypic culture, MMP9-deficient kidneys failed to secrete SCF, and addition of recombinant SCF partially rescued both apoptosis and the branching defect. In conclusion, these data show that MMP9 protects mesenchymal cells from apoptosis during kidney development and stimulates ureteric bud branching morphogenesis, most likely by releasing the soluble form of SCF, suggesting that normal renal development requires MMP9.

Matrix Metallopeptidase 2 Gene Polymorphism is Associated with Obesity in Korean Population

The aim of this study was to determine whether single nucleotide polymorphisms (SNPs) of matrix metallopeptidase 2 (MMP2) are associated with obesity. MMP2 is an enzyme with proteolytic activity against matrix and nonmatrix proteins, particularly basement membrane constituents. To identify the relationship between polymorphisms of MMP2 and overweight/obese, we genotyped 5 SNPs (rs17242319, rs1053605, rs243849, rs2287074, and rs10775332) of the coding region of MMP2 using the Golden Gate assay on an Illumina BeadStation 500 GX. One hundred and forty two overweight/obese (BMI >/=23) and 145 normal (BMI 18 to <23) subjects were analyzed. SNPStats, Haploview, HapAnalyzer, SNPAnalyzer, and Helixtree programs were used for the analysis of genetic data. A linkage disequilibrium (LD) block was discovered among the 5 SNPs selected, including rs17242319, rs1053605, rs243849, and rs2287074. Of the 5 polymorphisms, 2 synonymous SNPs [rs17242319 (Gly226Gly) and rs10775332 (Phe602Phe)] were found significant associations with overweight/obese. Recently, rs1132896 replaced rs17242319 as a new number (SNP database, BUILD 129). In haplotype analysis using Haploview, a haplotype (haplotype: CCCA) containing a meaningful polymorphism (rs17242319) was found to be significantly different. The results suggest that MMP2 may be associated with overweight/obese in Korean population.

Interleukin-1 receptor antagonist gene (IL-1RN) polymorphism is a predictive factor of clinical pregnancy after IVF

BACKGROUND

Only 25% of IVF transfer cycles lead to a clinical pregnancy, calling for continued technical progress but also more in depth analysis of patients' individual characteristics. The interleukin-1 (IL-1) system and matrix metalloproteinases (MMPs) are strongly implicated in embryo implantation. The genes coding for IL-1Ra (gene symbol IL-1RN), IL-1beta, MMP2 and MMP9 bear functional polymorphisms. We analysed the maternal genetic profile at these polymorphic sites in IVF patients, to determine possible correlations with IVF outcome.

METHODS

One hundred and sixty women undergoing an IVF cycle were enrolled and a buccal smear was obtained. The presence of IL-1RN variable number of tandem repeats and IL-1B + 3953, MMP2-1306 and MMP9-1562 single nucleotide substitutions were determined. Patients were divided into pregnancy failures (119), biochemical pregnancies (8) and clinical pregnancies (33).

RESULTS

There was a 40% decrease in IL-1RN*2 allele frequency (P = 0.024) and a 45% decrease in IL-1RN*2 carrier status in the clinical pregnancy group as compared to the pregnancy failure group (P = 0.017). This decrease was still statistically significant after a multivariate logistic regression analysis. The likelihood of a clinical pregnancy was decreased accordingly in IL-1RN*2 carriers: odds ratio = 0.349, 95% confidence interval = 0.2-0.8, P = 0.017. The IL-1B, MMP2 and MMP9 polymorphisms showed no correlation with IVF outcome.

CONCLUSIONS

IL-1RN*2 allele carriage is associated with a poor prognosis of achieving a pregnancy after IVF.