Cytochrome P450c17alpha 5'-untranslated region *T/C polymorphism in endometriosis

Polymorphisms and endometriosis: a systematic review and meta-analyses

BACKGROUND

Endometriosis is an estrogen-dependent gynecological disorder that affects at least 10% of women of reproductive age. It may lead to infertility and non-specific symptoms such as chronic pelvic pain. Endometriosis screening and diagnosis are difficult and time-consuming. Late diagnosis (with a delay ranging from 3.3 to 10.7 years) is a major problem and may contribute to disease progression and a worse response to treatment once initiated. Efficient screening tests might reduce this diagnostic delay. As endometriosis is presumed to be a complex disease with several genetic and non-genetic pathogenic factors, many researchers have sought to identify polymorphisms that predispose to this condition.

OBJECTIVE AND RATIONALE

We performed a systematic review and meta-analysis of the most regularly reported polymorphisms in order to identify those that might predispose to endometriosis and might thus be of value in screening.

SEARCH METHODS

The MEDLINE database was searched for English-language publications on DNA polymorphisms in endometriosis, with no date restriction. The PubTator text mining tool was used to extract gene names from the selected publications' abstracts. We only selected polymorphisms reported by at least three studies, having applied strict inclusion and exclusion criteria to their control populations. No stratification based on ethnicity was performed. All steps were carried out according to PRISMA guidelines.

OUTCOMES

The initial selection of 395 publications cited 242 different genes. Sixty-two genes (corresponding to 265 different polymorphisms) were cited at least in three publications. After the application of our other selection criteria (an original case-control study of endometriosis, a reported association between endometriosis and at least one polymorphism, data on women of reproductive age and a diagnosis of endometriosis in the cases established by surgery and/or MRI and confirmed by histology), 28 polymorphisms were eligible for meta-analysis. Only five of the 28 polymorphisms were found to be significantly associated with endometriosis: interferon gamma (IFNG) (CA) repeat, glutathione S-transferase mu 1 (GSTM1) null genotype, glutathione S-transferase pi 1 (GSTP1) rs1695 and wingless-type MMTV integration site family member 4 (WNT4) rs16826658 and rs2235529. Six others showed a significant trend towards an association: progesterone receptor (PGR) PROGINS, interCellular adhesion molecule 1 (ICAM1) rs1799969, aryl-hydrocarbon receptor repressor (AHRR) rs2292596, cytochrome family 17 subfamily A polypeptide 1 (CYP17A1) rs743572, CYP2C19 rs4244285 and peroxisome proliferator-activated receptor gamma (PPARG) rs1801282), and 12 showed a significant trend towards the lack of an association: tumor necrosis factor (TNF) rs1799964, interleukin 6 (IL6) rs1800796, transforming growth factor beta 1 (TGFB1) rs1800469, estrogen receptor 1 (ESR1) rs2234693, PGR rs10895068, FSH receptor (FSHR) rs6166, ICAM1 rs5498, CYP1A1 rs4646903, CYP19A1 rs10046, tumor protein 53 (TP53) rs1042522, X-ray repair complementing defective repair in Chinese hamster cells 1 (XRCC1) rs25487 and serpin peptidase inhibitor clade E member 1 (SERPINE1) rs1799889; however, for the 18 polymorphisms identified in the latter two groups, further studies of the potential association with the endometriosis risk are needed. The remaining five of the 28 polymorphisms were not associated with endometriosis: glutathione S-transferase theta 1 (GSTT1) null genotype, vascular endothelial growth factor alpha (VEGFA) rs699947, rs833061, rs2010963 and rs3025039.

WIDER IMPLICATIONS

By carefully taking account of how the control populations were defined, we identified polymorphisms that might be candidates for use in endometriosis screening and polymorphisms not associated with endometriosis. This might constitute the first step towards identifying polymorphism combinations that predispose to endometriosis (IFNG (CA) repeat, GSTM1 null genotype, GSTP1 rs1695, WNT4 rs16826658 and WNT4 rs2235529) in a large cohort of patients with well-defined inclusion criteria. In turn, these results might improve the diagnosis of endometriosis in primary care. Lastly, our present findings may enable a better understanding of endometriosis and improve the management of patients with this disease.

Genetic Characterization of Endometriosis Patients: Review of the Literature and a Prospective Cohort Study on a Mediterranean Population

The pathogenesis of endometriosis is unknown, but some evidence supports a genetic predisposition. The purpose of this study was to evaluate the recent literature on the genetic characterization of women affected by endometriosis and to evaluate the influence of polymorphisms of the wingless-type mammalian mouse tumour virus integration site family member 4 (WNT4), vezatin (VEZT), and follicle stimulating hormone beta polypeptide (FSHB) genes, already known to be involved in molecular mechanisms associated with the proliferation and development of endometriotic lesions in the Sardinian population. Materials and Methods: In order to provide a comprehensive and systematic tool for those approaching the genetics of endometriosis, the most cited review, observational, cohort and case-control studies that have evaluated the genetics of endometriosis in the last 20 years were collected. Moreover, 72 women were recruited for a molecular biology analysis of whole-blood samples—41 patients affected by symptomatic endometriosis and 31 controls. The molecular typing of three single nucleotide polymorphisms (SNPs) was evaluated in patients and controls: rs7521902, rs10859871 and rs11031006, mapped respectively in the WNT4, VEZT and FSHB genes. In this work, the frequency of alleles, genotypes and haplotypes of these SNPs in Sardinian women is described. Results: From the initial search, a total of 73 articles were chosen. An analysis of the literature showed that in endometriosis pathogenesis, the contribution of genetics has been well supported by many studies. The frequency of genotypes observed in the groups of the study population of 72 women was globally coherent with the law of the Hardy–Weinberg equilibrium. For the SNP rs11031006 (FSHB), the endometriosis group did not show an increase in genotypic or allelic frequency due to this polymorphism compared to the control group (p = 0.9999, odds ratio (OR) = 0.000, 95% confidence interval (CI), 0.000–15.000 and p = 0.731, OR = 1639, 95% CI, 0.39–683, respectively, for the heterozygous genotype and the polymorphic minor allele). For the SNP rs10859871 (VEZT), we found a significant difference in the frequency of the homozygous genotype in the control group compared to the affected women (p = 0.0111, OR = 0.0602, 95% CI, 0.005–0.501). For the SNP rs7521902 (WNT4), no increase in genotypic or allelic frequency between the two groups was shown (p = 0.3088, OR = 0.4133, 95% CI, 0.10–1.8 and p = 0.3297, OR = 2257, 95% CI, 0.55–914, respectively, for the heterozygous genotype and the polymorphic minor allele). Conclusion: An analysis of recent publications on the genetics of endometriosis showed a discrepancy in the results obtained in different populations. In the Sardinian population, the results obtained do not show a significant association between the investigated variants of the genes and a greater risk of developing endometriosis, although several other studies in the literature have shown the opposite. Anyway, the data underline the importance of evaluating genetic variants in different populations. In fact, in different ethnic groups, it is possible that specific risk alleles could act differently in the pathogenesis of the disease.

Genetics of endometriosis: a comprehensive review

This review aimed to critically evaluate the review, observational, cohort, and case-control studies performed so far in order to assess the association between endometriosis and genetics. The search strategies used included an online search of the MEDLINE database and a manual search of relevant publications and reviews. Additional reports were collected by systematically reviewing all references from the retrieved papers. Family studies have long suggested that genetic factors play a role in the etiology of endometriosis. Nevertheless, until now, studies on candidate genes have revealed inconsistent and contradictory evidence, leading to more questions rather than clear answers. It is possible that recent technological improvements in genetic evaluation could allow for a better understanding of the pathogenic mechanisms of endometriosis in the near future.

CYP17A1 rs743572 polymorphism might contribute to endometriosis susceptibility: evidences from a case-control study

This case-control study was aimed to evaluate the influence of cytochrome P450 family 17 subfamily A member 1 (CYP17A1) gene rs743572 polymorphism for the susceptibility to endometriosis.Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) was used to genotype rs743572 polymorphism in 143 endometriosis patients and 148 healthy controls. Hardy-Weinberg equilibrium (HWE) test was utilized to detect the representativeness of the study subjects. Association strength was presented by odds ratios (ORs) with corresponding 95% confidence intervals (CIs).Genotype distribution of rs743572 polymorphism was conformed to HWE test both in case and control groups, revealing the good representativeness of our study subjects. Significantly positive association was discovered between rs743572 TT genotype and endometriosis susceptibility (P = .042, OR = 1.952, 95% CI = 1.020-3.736). Rs743572 T allele was more frequently discovered in cases than that in controls, revealing the enhanced susceptibility to endometriosis (P = .041, OR = 1.407, 95% CI = 1.014-1.951). Confounding factors (age and body mass index) were utilized to adjust the results, and then we found that the association strength had no significant changes (TT vs CC, P = .039, OR = 1.961, 95% CI = 1.023-3.742; T vs C, P = .038, OR = 1.413, 95% CI = 1.016-1.957). But we failed to find any obvious association of rs743572 genotypes with endometriosis stages and characteristics.T allele of rs743572 polymorphism might act as a risk factor for endometriosis, although it had no effects on the disease stages and basic features.

Association study between CYP17 gene polymorphism and endometriosis risk: a meta-analysis

The cytochrome P450 subfamily 17 (CYP17) gene T > C polymorphism is associated with endometriosis risk. However, studies on the association between the genotyping of MspA1 polymorphism in the 5'-untranslated region of the CYP17 gene and endometriosis risk have reported controversial results. The aim of the present study was to obtain a more precise estimate of the relationship of CYP17 gene polymorphism with endometriosis risk. Relevant articles published up to April 2014 were obtained from Pubmed, Embase, and Cochrane Central electronic databases. Case-control studies about the association between CYP17 gene polymorphisms and endometriosis were selected. Eligible data were extracted by two independent reviewers. The strength of the association between CYP17 and endometriosis was assessed by pooled odds ratios (OR) with 95% confidence intervals (CI). Eligible case-control studies involving 1000 cases and 1167 controls were analyzed from 280 studies. The pooled results showed no association between the CYP17 gene T > C polymorphism and endometriosis risk in the overall population (CC vs TT: OR = 0.92, 95% CI = 0.52-1.61, P = 0.762; TC vs TT: OR = 1.01, 95% CI = 0.72-1.42, P = 0.949; dominant model: OR = 0.94, 95% CI = 0.64-1.39, P = 0.763; recessive model: OR = 0.93, 95% CI = 0.64-1.35, P = 0.712). In the subgroup analysis based on ethnicity, no significant association was found in Asians, Caucasians and mixed population under a recessive model (Asians: OR = 0.76, 95% CI = 0.53-1.07, P = 0.118; Caucasians: OR = 2.47, 95% CI = 0.45-13.66, P = 0.300; mixed population: OR = 1.40, 95% CI = 0.65-3.02, P = 0.712). In conclusion, the meta-analysis suggested that the CYP17 gene polymorphism was not associated with endometriosis risk. Considering the limited sample size and ethnicity included in our meta-analysis, an updated meta-analysis needs to be conducted when larger and more well-designed studies are published.

Screening of a panel of steroid-related genes showed polymorphisms of aromatase genes confer susceptibility to advanced stage endometriosis in the Taiwanese Han population

OBJECTIVE

To establish a multilocus model for studying the effect of steroid-related genes on advanced stage endometriosis.

MATERIALS AND METHODS

A total of 121 patients with advanced stage endometriosis and 171 control women were included. Eighteen single-nucleotide polymorphisms (SNPs) from nine genes (HSD17B1, HSD17B2, HSD17B5, HSD17B6, CYP17, CYP19, ERα, ERβ, and PGR) were genotyped using the TaqMan assays. Logistic regression models were used to evaluate the genetic effects, with adjustment for other covariates.

RESULTS

Only the presence of the mutant CYP19 (aromatase gene) was associated with a significantly increased risk of endometriosis after adjusting for age, BMI, and parity (p = 0.002, OR = 2.69; 95% CI = 1.44-5.02). No association was ascertained between the other investigated SNPs and endometriosis.

CONCLUSION

Polymorphisms of the aromatase gene confer susceptibility to advanced stage endometriosis in the Taiwanese Han population.

The polymorphism (-600 C>A) of CpG methylation site at the promoter region of CYP17A1 and its association of male infertility and testosterone levels

Cytochrome P450, family 17, subfamily A, polypeptide 1 (CYP17A1) is a key regulatory enzyme in the steroidogenic pathway. The functional and clinical relevance of novel CYP17A1 promoter single nucleotide polymorphism (-600 C>A, rs17115149) was investigated with male infertility. Case-control association study of CYP17A1 from 456 infertile men performed with 465 normal fertile men. The rs17115149 at the promoter region of CYP17A1 was significantly associated with Oligoasthenoteratozoospermia (OAT, P=0.0015, n=265). 5-aza-dC treatment to B lymphocyte cells increased the CYP17A1 expression. Direct bisulfite sequencing of five human tissues showed that the rs17115149 is located at -600bp (-600C>A) before transcription start site within the CpG islands of CYP17A1 promoter. This -600 Cytosine of CpG site was highly methylated in colon and stomach tissues, but low methylated in adrenal gland, kidney and testis with higher CYP17A1 RNA expression. Especially, this polymorphism is statistically significant associated with testosterone levels from infertile males (n=197, P<0.05). CYP17A1 promoter polymorphism (rs17115149, -600C>A) is a functional regulatory SNP which associated with its expression possibly by epigenetic pathway, which may signify a genetic risk factor for male infertility.

Polymorphic variants of CYP17 and CYP19A and risk of infertility in endometriosis

OBJECTIVE

Endometriosis is recognized as an estrogen-dependent disease. There are conflicting data demonstrating single nuclear polymorphisms (SNPs) of CYP17 and CYP19 steroidogenic genes as related to endometriosis risk. We assessed the CYP17 5'-untranslated region -34 A/G (rs743572) and CYP19 Ex10 + C1558T (rs10046) SNPs in stage I-II endometriosis.

DESIGN

Case-control study.

SETTING

Division of reproduction at a university department in Poland.

POPULATION

A total of 115 women with diagnosed stage I-II endometriosis according to the revised American Society for Reproductive Medicine (rASRM) classification and 197 fertile women as controls.

METHODS

The SNPs CYP17 -34 A/G and CYP19 Ex10 + C1558T were identified by high-resolution melting curve analysis.

MAIN OUTCOME MEASURES

Genotype prevalence and odds ratio for recessive and dominant genetic model for CYP17 and CYP19 SNPs.

RESULTS

We observed a significantly increased CYP17 GG and GA genotype frequency in women diagnosed with rASRM stage I-II endometriosis compared with fertile women (OR = 2.4; 95% CI 1.4-4.2, p = 0.002). We also found a significantly increased CYP17 G allele frequency in cases compared with controls (OR = 1.6; 95% CI 1.2-2.2, p = 0.004). There were no significant differences in the distribution of the CYP17 GG genotype and CYP19 Ex10 + C1558T polymorphism between women diagnosed with rASRM stage I-II endometriosis and controls.

CONCLUSION

The CYP17 -34 G variant, previously associated with increased 17β-estradiol production, displayed a contribution to stage I-II endometriosis in women from a Polish population. Increased 17β-estradiol concentration in carriers of the CYP17 -34 G variant might contribute to endometriosis and associated pathological processes.

CYP17 and CYP2C19 gene polymorphisms in patients with endometriosis

Endometriosis seems to be the result of a complex interaction between environmental factors and various genes. In this regard, the cytochrome subfamily 17 (CYP17) may play an important role by altering the biosynthesis of sex steroids. CYP2C19 is also an important member of the cytochrome P450 (CYP) family, and related mutations may result in an inability to fully metabolize environmental chemicals and cytokines, leading to several diseases. This study sought to determine whether there is a relationship between endometriosis and CYP17 T>C, CYP2C19 *2 and CYP2C19 *3 polymorphisms. When samples from 46 patients with endometriosis and 39 healthy controls were analysed, A2A2 type mutation of the CYP17 gene was observed to be more frequent in patients with endometriosis (34.8 versus 7.7%, P = 0.003). No association was found between the severity of endometriosis and CYP2C19 *2 or CYP2C19 *3 polymorphisms of the CYP2C19 gene. These results suggest that mutations related with sex steroid metabolism seem to have an important role in endometriosis. However, the relation between detoxification ability and endometriosis should be examined in further studies with larger sample sizes.

CYP17 and CYP19 gene polymorphisms in women affected with endometriosis

OBJECTIVE

To investigate whether CYP17 T>C polymorphism and polymorphisms C1558T and Val80 of CYP19 are related to endometriosis.

DESIGN

Clinical study.

PATIENT(S)

Women affected with endometriosis (n = 104) and control group (n = 86). The diagnosis of endometriosis was confirmed by the histologic examination of the endometriotic lesions.

RESULT(S)

In patients affected with endometriosis, we observed that AA and CC genotypes were significantly represented in Val80 and C1558T polymorphisms of CYP19.

CONCLUSION(S)

The molecular mechanisms that underlie the development of endometriosis are unclear. Both environmental and genetic factors are involved in the pathogenesis of the disease. The inheritable susceptibility to endometriosis justifies the growing interest in identifying genes and/or genetic polymorphisms that predispose women to an increased risk of developing endometriosis. The identification of single-nucleotide polymorphism (SNP), probably linked to endometriosis, could help to explain its pathogenesis.

Common Variation in the CYP17A1 and IFIT1 Genes on Chromosome 10 Does Not Contribute to the Risk of Endometriosis

Endometriosis is a complex disease involving multiple susceptibility genes and environmental factors. Our previous studies on endometriosis identified a region of significant linkage on chromosome 10q. Two biological candidate genes (CYP17A1 and IFIT1) located on chromosome 10q, have previously been implicated in endometriosis and/or uterine function. We hypothesized that variation in CYP17A1 and/or IFIT1 could contribute to the risk of endometriosis and may account for some of the linkage signal on chromosome 10q. We genotyped 17 single nucleotide polymorphisms (SNPs) in the CYP17A1 and IFIT1 genes including SNP rs743572 previously associated with endometriosis in 768 endometriosis cases and 768 unrelated controls. We found no evidence for association between endometriosis and individual SNPs or SNP haplotypes in CYP17A1 and IFIT1. Common variation in these genes does not appear to be a major contributor to endometriosis susceptibility in our Australian sample.

Functional genetic polymorphisms and female reproductive disorders: part II--endometriosis

BACKGROUND

Endometriosis has a strong genetic component, and numerous genetic studies have been reported.

METHODS

We have systematically reviewed these studies and included 114 in our final selection.

RESULTS

We found no consistent evidence linking endometriosis with specific polymorphisms in genes encoding inflammatory mediators, proteins involved in sex steroid metabolism, vascular function and tissue remodelling. Although a number of polymorphisms have been associated with endometriosis in selected populations, the associations have not been independently confirmed, either because only single studies were carried out on these markers/genes or because other studies reported no association. The most solid evidence linking specific polymorphisms to endometriosis came from studies investigating glutathione-S-transferase, a phase II detoxification enzyme. Carriage of the GSTT1 null deletion variant showed consistent association with endometriosis with a 29% increased risk; however, it cannot be excluded that this result was due to publication bias, and this association should be independently confirmed in large-scale, well-designed case–control studies.

CONCLUSIONS

The evidence of an association between genetic polymorphisms and endometriosis is weak. Carriage of the GSTT1 null deletion may moderately increase the risk of this disease. We suggest that the methodology of association studies should be improved in order to identify and validate associations in endometriosis.

Endometriosis and Genetic Polymorphisms

Endometriosis is a benign gynecological disease with an unclear pathophysiology characterized by ectopic endometrium causing endometrium-like inflammatory lesions outside the uterine cavity. Recently, a number of studies have investigated genetic polymorphisms as a possible factor contributing to the development of endometriosis. In this review, we have summarized current data regarding genes with nucleotide polymorphisms investigated with regard to endometriosis. We searched PubMed for publications on endometriosis and polymorphism and found 108 publications between January 1979 and September 2005. These were classified according to the type of genetic polymorphism investigated and whether the result favored or did not favor association with endometriosis. We found a strikingly large amount of conflicting results. About 50% of the reviewed studies demonstrated positive correlations between different polymorphisms and endometriosis. This relation is most clearly seen in groups 1 (cytokines and inflammation), 2 (steroid-synthesizing enzymes and detoxifying enzymes and receptors), 4 (estradiol metabolism), 5 (other enzymes and metabolic systems), and 7 (adhesion molecules and matrix enzymes). Group 8 (apoptosis, cellcycle regulation, and oncogenes) seemed to be negatively correlated with the disease, whereas group 3 (hormone receptors), 6 (growth factor systems), and especially 9 (human leukocyte antigen system components) showed a relatively strong correlation. The review indicates that polymorphisms may have a limited value in assessing possible development of endometriosis.

TARGET AUDIENCE

Obstetricians & Gynecologists, Family Physicians.

LEARNING OBJECTIVES

After completion of this article, the reader should be able to recall the complexity of attempting to link endometriosis to single nucleotide polymorphisms (SNPs), explain that the literature is varied on results and recommendations and is population specific, and state that there are some SNP relationships that are clinically stronger than others.

Genotype distribution of estrogen receptor-alpha, catechol-O-methyltransferase, and cytochrome P450 17 gene polymorphisms in Caucasian women with uterine leiomyomas

OBJECTIVE

To evaluate the association between the presence of uterine leiomyomas and three functional single nucleotide polymorphisms (SNPs) of the estrogen receptor alpha (ESR1), catechol-O-methyltransferase (COMT), and cytochrom P450 17 (CYP17A) genes, which have been described to modify the estrogen metabolism.

DESIGN

Prospective case control study.

SETTING

Academic research institution.

PATIENT(S)

One hundred thirty women with clinically and surgically diagnosed uterine leiomyomas and 139 population controls.

INTERVENTION(S)

Peripheral venous puncture.

MAIN OUTCOME MEASURE(S)

Polymerase chain reaction and pyrosequencing were performed to genotype women with respect to the ESR1 IVS1-397 T/C (PvuII), COMT G158A, and the CYP17A 34T-->C SNPs.

RESULT(S)

Comparing women with uterine leiomyomas and controls, no statistically significant differences with respect to allele frequency and genotype distribution were ascertained for ESR1 IVS 1-397 T/C (PvuII) (P=0.9 and P=0.6, respectively), COMT G158A (P=0.3 and P=0.6, respectively), and CYP17A 34T-->C (P=0.1 and P=0.5, respectively). When all two-way interactions of investigated SNPs were ascertained, no significant interactions were observed. In a multivariate model, no SNP was significantly associated with leiomyomas.

CONCLUSION(S)

Carriage of the ESR1 IVS1-397 T/C (PvuII), COMT G158A, and the CYP17A 34T-->C SNPs is not associated with the susceptibility to uterine leiomyoma in a Caucasian population.