Androgen receptor trinucleotide polymorphism in endometriosis

Recent insights explaining susceptibility to endometriosis-From genetics to environment

Endometriosis is a disease with a heterogeneous pathogenesis, explained by multiple theories, and also with a polymorphic presentation. The purpose of this literature review is to systematize the genetic, inflammatory, and environmental factors related to the pathophysiology of endometriosis. Current evidence suggests that endometriosis is a complex inherited genetic condition, in which the genes that determine susceptibility to the disease interact with the environment to develop different phenotypes. Genetic variants associated with risk of endometriosis have been identified in several genome-wide association studies, in addition to a group of genes related to the pathophysiology of endometriosis, namely the estrogen, progesterone and androgen receptors and the cytochrome P450 gene, as well as the p53 gene. The role of inflammation is controversial; however, it is an essential process, both in the initiation and perpetuation of the disease, in and outside the pelvis. Alterations in reactive oxygen species pathways that consequently determine oxidative stress are typical in the inflammatory environment of endometriosis. The role of environmental factors is a relatively new and broad-spectrum topic, with inconsistent evidence. Multiple factors have been studied such as endocrine-disrupting chemicals, metals, intrauterine exposure to diethylstilbesterol and lifestyle risk factors. In conclusion, endometriosis remains a mysterious condition, with multifactorial factors involved in its pathophysiology. The progress that has been made in the genetic predisposition to endometriosis may allow the establishment of new therapeutic targets. On the other hand, understanding the role of the environment in this disease may allow preventive intervention, minimizing its incidence and/or severity. This article is categorized under: Reproductive System Diseases > Molecular and Cellular Physiology Reproductive System Diseases > Environmental Factors Reproductive System Diseases > Genetics/Genomics/Epigenetics.

Network pharmacology and experimental validation to explore the potential mechanism of Sanjie Zhentong Capsule in endometriosis treatment

PURPOSE

Sanjie Zhentong Capsule (SZC) is gradually becoming widely used in the treatment of endometriosis (EMs) and has demonstrated an excellent curative effect in the clinic. However, the active components and mechanisms of Sanjie Zhentong Capsule (SZC) in the treatment of endometriosis (EMs) remain unclear, and further research is needed to explore the effects of Sanjie Zhentong Capsule (SZC).

MATERIALS AND METHODS

First, a drug target database of Sanjie Zhentong capsule (SZC) was established by consulting the TCMSP database and related literature. An endometriosis (EMs) disease target database was then established by consulting the GeneCards, OMIM and Drug Bank databases. The overlapping genes of SZC and EMs were determined, and protein-protein interactions (PPIs), gene ontology (GO) and Kyoto Gene and Genome Encyclopedia (KEGG) analyses were performed to predict the potential therapeutic mechanisms. Molecular docking was used to observe whether the key active ingredients and targets predicted by network pharmacology had good binding energy. Finally, in vitro experiments such as CCK-8, flow cytometry and RT-PCR assays were carried out to preliminarily verify the potential mechanisms.

RESULTS

Through the construction of a pharmacological network, we identified a total of 28 active components in SZC and 52 potential therapeutic targets. According to GO and KEGG enrichment analyses, the effects of SZC treatment may be related to oxidative stress, steroid metabolism, apoptosis and proliferation. We also experimentally confirmed that SZC can regulate the expression of steroid hormone biosynthesis-related genes, inhibit ectopic endometrial stromal cell (EESC) proliferation and oxidative stress, and promote apoptosis.

CONCLUSION

This study explored the potential mechanism of SZC in the treatment of EMs through network pharmacology and experiments, providing a basis for further future research on SZC in the treatment of EMs.

Androgen Signaling in Uterine Diseases: New Insights and New Targets

Common uterine diseases include endometriosis, uterine fibroids, endometrial polyps, endometrial hyperplasia, endometrial cancer, and endometrial dysfunction causing infertility. Patients with uterine diseases often suffer from abdominal pain, menorrhagia, infertility and other symptoms, which seriously impair their health and disturb their lives. Androgens play important roles in the normal physiological functions of the uterus and pathological progress of uterine diseases. Androgens in women are synthesized in the ovaries and adrenal glands. The action of androgens in the uterus is mainly mediated by its ligand androgen receptor (AR) that regulates transcription of the target genes. However, much less is known about the signaling pathways through which androgen functions in uterine diseases, and contradictory findings have been reported. This review summarizes and discusses the progress of research on androgens and the involvement of AR in uterine diseases. Future studies should focus on developing new therapeutic strategies that precisely target specific AR and their related signaling pathways in uterine diseases.

Sex hormone-related polymorphisms in endometriosis and migraine: A narrative review

Some evidence indicates endometriosis and migraine have a common genetic predisposition in sex-hormone genes, which could have important implications for the treatment of these two heterogenous conditions. To date, the genes responsibility remains unknown. Based on the biological hypothesis that polymorphisms of genes involved in sex-hormone pathways may influence estrogen levels and phenotypes of both disorders, we did a literature search for candidate sex-hormone genes and genes involved in the metabolism of estradiol. The aim was to review the evidence for shared sex-hormone-related polymorphisms between endometriosis and migraine and provide an exhaustive overview of the current literature. We included case-control studies investigating associations between candidate sex-hormone-related genes and the disorders endometriosis and migraine, respectively. Results showed three overlapping sex-hormone-associated polymorphisms in estrogen receptor genes that are associated with both conditions. To confirm possible associations with other sex-hormone genes, larger studies are needed.

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.

Androgen receptor cytosine, adenine, and guanine trinucleotide repeat polymorphism in Korean patients with endometriosis: A case-control study

STUDY OBJECTIVE

To investigate the association between the androgen receptor (AR) cytosine, adenine, and guanine (CAG) repeat polymorphisms and endometriosis.

STUDY DESIGN

A prospective case-control, genetic association study was performed on women with surgically proven endometriosis (n=421) and controls free of endometriosis (n=349). AR CAG repeat lengths were determined from peripheral blood samples. The difference in the frequency of each alleles were compared in patients with endometriosis and controls using Chi-square test.

MAIN RESULTS

No significant difference in biallelic length mean between patients and controls was observed. Alleles containing 24 CAG repeats were significantly more frequent in stage I-II (mild) endometriosis than in the control samples (19.8% and 13.3%, respectively; OR 1.60, 95% CI 1.04-2.47). Additionally, a higher frequency of both alleles with 24 or more CAG repeats was observed in individuals with mild endometriosis, in comparison with the controls (25.6% and 15.2%, respectively; OR 1.92, 95% CI 1.09-3.38).

CONCLUSIONS

AR gene CAG repeat polymorphisms are associated with the increased risk of mild endometriosis.

Integrative Analysis Reveals Regulatory Programs in Endometriosis

Endometriosis is a common gynecological disease found in approximately 10% of reproductive-age women. Gene expression analysis has been performed to explore alterations in gene expression associated with endometriosis; however, the underlying transcription factors (TFs) governing such expression changes have not been investigated in a systematic way. In this study, we propose a method to integrate gene expression with TF binding data and protein-protein interactions to construct an integrated regulatory network (IRN) for endometriosis. The IRN has shown that the most regulated gene in endometriosis is RUNX1, which is targeted by 14 of 26 TFs also involved in endometriosis. Using 2 published cohorts, GSE7305 (Hover, n = 20) and GSE7307 (Roth, n = 36) from the Gene Expression Omnibus database, we identified a network of TFs, which bind to target genes that are differentially expressed in endometriosis. Enrichment analysis based on the hypergeometric distribution allowed us to predict the TFs involved in endometriosis (n = 40). This included known TFs such as androgen receptor (AR) and critical factors in the pathology of endometriosis, estrogen receptor α, and estrogen receptor β. We also identified several new ones from which we selected FOXA2 and TFAP2C, and their regulation was confirmed by quantitative real-time polymerase chain reaction and immunohistochemistry (IHC). Further, our analysis revealed that the function of AR and p53 in endometriosis is regulated by posttranscriptional changes and not by differential gene expression. Our integrative analysis provides new insights into the regulatory programs involved in endometriosis.

Pathogenesis of endometriosis: the role of genetics, inflammation and oxidative stress

INTRODUCTION

Endometriosis is defined as the presence of endometrial tissue outside the uterine cavity.

MATERIALS AND METHODS

The etiology of this multifactorial disease is still unresolved and an increasing number of studies suggest that genetic, hormonal, environmental, immunological and oxidative factors may all play an important role in the pathogenesis of this disorder.

CONCLUSIONS

In this literature review, inflammatory activity, oxidative stress as well as genetic abnormalities and mutations have been studied in an effort to identify factors predisposing to endometriosis.

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.

Haplotype analysis of the matrix metalloproteinase-9 gene associated with advanced-stage endometriosis

OBJECTIVE

To investigate whether the -1562C>T, R279Q, P574R, and R668Q polymorphisms of the matrix metalloproteinase-9 (MMP-9) gene are related to endometriosis.

DESIGN

Case-control study.

SETTING

University-based hospital in Korea.

PATIENT(S)

Patients with endometriosis stage III/IV (n = 225) who underwent pelvic surgery and controls (n = 198) with no endometriosis in a Korean population.

INTERVENTION(S)

Peripheral blood samples were collected by venipuncture.

MAIN OUTCOME MEASURE(S)

Frequencies of genotypes and haplotypes were compared with the risk of endometriosis including -1562C>T, R279Q, P574R, and R668Q polymorphisms of MMP-9.

RESULT(S)

In the two-locus haplotype analyses using the four single nucleotide polymorphisms (SNPs), an increase in the distribution of the R279Q/P574R (2678G>A/4859C>G) (AC haplotype: odds ratio [OR] = 3.180, 95% confidence interval [CI] = 1.956-5.170; GG haplotype: OR = 4.374, 95% CI = 2.376-8.053) and -1562C>T/R668Q (-1562C>T/5546G>A) (CA haplotype: OR = 3.280, 95% CI = 1.406-7.653) haplotypes was significantly associated with endometriosis. By contrast, the risk of endometriosis was not associated with the individual SNPs studied.

CONCLUSION(S)

These findings suggest that haplotype analysis was more informative than SNP analysis. The haplotypes in the MMP-9 gene may correlate with the progression of endometriosis, and further study of these variations might improve our understanding of the pathogenesis of 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.

Phenotypic heterogeneity of mutations in androgen receptor gene

Androgen receptor (AR) gene has been extensively studied in diverse clinical conditions. In addition to the point mutations, trinucleotide repeat (CAG and GGN) length polymorphisms have been an additional subject of interest and controversy among geneticists. The polymorphic variations in triplet repeats have been associated with a number of disorders, but at the same time contradictory findings have also been reported. Further, studies on the same disorder in different populations have generated different results. Therefore, combined analysis or review of the published studies has been of much value to extract information on the significance of variations in the gene in various clinical conditions. AR genetics has been reviewed extensively but until now review articles have focused on individual clinical categories such as androgen insensitivity, male infertility, prostate cancer, and so on. We have made the first effort to review most the aspects of AR genetics. The impact of androgens in various disorders and polymorphic variations in the AR gene is the main focus of this review. Additionally, the correlations observed in various studies have been discussed in the light of in vitro evidences available for the effect of AR gene variations on the action of androgens.

Estrogen receptor alpha-351 XbaI*G and -397 PvuII*C-related genotypes and alleles are associated with higher susceptibilities of endometriosis and leiomyoma

Endometriosis and leiomyoma are both common estrogen-related gynaecological diseases. We aimed to elucidate the association of estrogen receptor alpha (ERalpha)-351 A>G (XbaI) and -397 T>C (PvuII) gene polymorphisms with endometriosis and leiomyoma. Women were divided into three groups: (i) severe endometriosis (n = 112), (ii) leiomyoma (n = 106) and (iii) normal controls (n = 110). Genomic DNA was obtained from peripheral leukocytes. ERalpha-351 A/G XbaI and -397 T/C PvuII polymorphisms were assayed by the method of PCR and restriction fragment length polymorphism (RFLP). Genotypes and allelic frequencies in each group were compared. The genotype/allele frequencies of ERalpha-351 and -397 polymorphisms in endometriosis or leiomyoma groups were different from those of normal controls. ERalpha mutant-related genotypes/alleles (-351G and -397C) presented higher percentages in the endometriosis/leiomyoma population compared with normal controls. Proportions of ERalpha-351 AA/AG/GG genotypes and A/G alleles in each group were (i) 26.8/57.1/16.1 and 55.4/44.6%; (ii) 19.8/52.8/27.4 and 46.2/53.8% and (iii) 33.6/64.6/1.8 and 65.9/34.1%. Proportions of ERalpha-397 TT/TC/CC genotypes and T/C alleles in each group were (i) 24.1/60.7/15.2 and 54.5/45.5%; (ii) 23.6/70.8/5.6 and 59/41% and (iii) 54.5/40/5.5 and 74.5/25.5%. We concluded that ERalpha-351 XbaI*G- and -397 PvuII*C-related genotypes/alleles were correlated with higher susceptibilities of endometriosis or leiomyoma, which might be associated with related pathogeneses.

Adenomyosis: the pathophysiology of an oestrogen-dependent disease

Adenomyosis uteri is a common gynaecological disorder that is characterized by the presence of ectopic endometrial glands and stroma in the myometrium. Although adenomyosis and endometriosis are different diseases, both of them grow and regress in an oestrogen-dependent fashion. Polymorphisms in the oestrogen receptor alpha gene are associated with a risk of adenomyosis. Adenomyotic tissue contains steroid receptors as well as aromatase and sulphatase enzymes. Together with the circulating oestrogen, locally produced oestrogens stimulate the growth of tissue mediated by the oestrogen receptors. Oestrogen metabolism, including the expression pattern of aromatase and the regulation of 17beta-hydroxysteroid dehydrogenase type 2 is altered in the eutopic endometrium of women with endometriosis, adenomyosis, and/or leiomyomas compared to that in the eutopic endometrium of women without disease. In addition to the conventional hormonal treatment with gonadotropin-releasing hormone agonists and danazol, the use of steroid-releasing intrauterine devices may be applicable to clinics.

Evaluation of clinical parameters and estrogen receptor alpha gene polymorphisms for patients with endometriosis

Endometriosis is a chronic inflammatory disease, which is especially found in women with subfertility problems with an incidence of up to 30%. The disease is considered an estrogen-dependent disorder, where DNA polymorphisms of the estrogen receptor α (ERα) in connection with endometriosis are controversially discussed. From a German population of women, clinical data associated with the disease, including the American Fertility Society (AFS) I–IV classification, and non-clinical parameters were evaluated statistically in endometriosis patients (n= 98) and in control women (n= 98) without endometriosis. Using a multivariate statistical analysis, significant associations of endometriosis with dysmenorrhea (P< 0.001) and allergies against medicaments (P= 0.042) were found. A positive trend between first grade family history of endometriosis and allergies against medicaments was also observed, suggesting a genetic relationship. From both collectives, DNA from peripheral blood was analyzed for the frequency of the ERα DNA polymorphisms Xba1 (A/G) and PvuII (T/C) in intron 1 and the ERα exonic DNA polymorphism (G229A) with an amino acid exchange (Gly77Ser) in the transactivation domain. DNA samples from endometriosis lesions and control tissues from the same collectives were also analyzed for the exonic G229A polymorphism. Only homozygote wild-type alleles for the polymorphism G229A were found, making it a rare polymorphism in mid-European individuals. Allele types for the PvuII and Xba1 polymorphisms were analyzed with the observed statistically significant clinical parameters and showed no significant association with endometriosis; however a trend with AFS IV was noted, which could contribute to lesion severity. In conclusion, the analyzed polymorphisms in the ERα do not have a functional role concerning specific clinical parameters associated with endometriosis.

Polymorphism for transforming growth factor beta 1-509 (TGF-B1-509): association with endometriosis

Transforming growth factor beta (TGF-B) family members are multi-functional cytokines that play a key role in cellular growth, proliferation, and differentiation. The aim of the study was to investigate whether the TGF-B1-509 gene polymorphism could be used as a marker of susceptibility in endometriosis. Women were divided into two groups: endometriosis (n = 150) and non-endometriosis (n = 159). Polymorphisms for TGF-B 1-509 genes were amplified by polymerase chain reaction and detected after restriction enzyme digestion. Genotypes and allelic frequencies in both groups were compared. Genotype proportions and allele frequencies of TGF-B1 gene polymorphisms differed significantly in both groups. Proportions of C homozygote, heterozygote, and T homozygote for TGF-B1 gene polymorphisms were 9.3/61.3/29.4% in the endometriosis group and 41.3158.510% in the non-endometriosis group. Alleles C and T for TGF-B1 gene polymorphism were 40/60% (endometriosis) and 70.8/29.2% (non-endometriosis). Association of endometriosis with TGF-B 1-509 gene polymorphism exists. T homozygote and T allele for TGF-B1 are associated with higher susceptibility to endometriosis.

Association of endometriosis risk and genetic polymorphisms involving sex steroid biosynthesis and their receptors: a meta-analysis

Endometriosis is a sex steroids-dependent disease. It has been postulated that certain genetic polymorphisms involved in sex steroids biosynthesis and metabolisms may be associated with increased risk of developing endometriosis. Despite a deluge of reports of positive associations of endometriosis with numerous polymorphisms involving sex steroids production and metabolism, the results are often conflicting. We performed a meta-analysis of 12 association studies on 5 genes (CYP17, CYP19, AR, PR and ER). We found that many reported positive findings were not supported by the data due to faulty analysis. There have been no functional data that support a putative relationship of these genetic polymorphisms with endometriosis. A handful of positive findings so far have not been independently replicated, and should be viewed as preliminary. In addition, these findings should be counterbalanced by legitimate concerns of multiple comparisons, small prior probability of association with a particular polymorphism, proper selection of controls, and lack of replication (at least until now). In future association studies, it may be productive to put more thought to study design, execution, and data analysis.

Androgen receptor trinucleotide polymorphism in leiomyoma

OBJECTIVE

Androgen receptor (AR) was detected in leiomyoma. AR gene has a polymorphic microsatellite encoding cytosine, adenine, and guanine (CAG) repeats. We aimed to investigate the association between the AR gene CAG repeats and leiomyoma.

METHODS

Women were divided into two groups: (1) leiomyoma (n = 159); (2) non- leiomyoma groups (n = 129). Their CAG repeats were detected by polymerase chain reaction. The CAG repeats ranged in length from 168 bp (9 CAG repeats, genotype A) to 234 bp (31 CAG repeats, genotype W). Distributions of CAG repeats in both groups were compared.

RESULTS

Genotype proportions of different CAG repeats for AR gene in both groups were significantly different. The genotype S (27 CAG repeats) is associated with higher susceptibility of leiomyoma. Distribution of CAG repeats in both groups appeared mono-peak distributions. Percentages of genotypes K-S (19-27 CAG repeats) in leiomyoma and non-leiomyoma groups were: (1) 5,11,19.5, 10.4, 12.9, 8.8, 7.5, 5.7, 4.4%; (2) 5.4, 14.3,16.7, 12.8, 12.4, 5.8, 9.3, 7,1.2%.

CONCLUSIONS

AR trinucleotide polymorphism is associated with leiomyoma susceptibility. The 27 CAG repeats is related with higher risk of leiomyoma.

Estrogen receptor alpha dinucleotide repeat and cytochrome P450c17alpha gene polymorphisms are associated with susceptibility to endometriosis

OBJECTIVE

To investigate the association of endometriosis with estrogen receptor alpha (ER alpha) and cytochrome P450c17alpha (CYP17) gene polymorphisms in light of the fact that estrogen plays a role in the pathogenesis of endometriosis and the CYP17 enzyme is involved with estrogen biosynthesis.

DESIGN

Prospective study.

SETTING

Genetics and gynecology units.

PATIENT(S)

All patients were divided into two groups: group 1, women with endometriosis (n = 119); group 2, normal controls (n = 108).

INTERVENTION(S)

A dinucleotide (thymine-adenine [TA]) repeat polymorphism lying upstream of the ER alpha gene and A1/A2 polymorphism of the CYP17 gene were amplified by polymerase chain reaction, enzyme restriction, and electrophoresis.

MAIN OUTCOME MEASURE(S)

The ER genotypes were classified into A through T (TA repeats, 10-29). The CYP17 genotypes included indigestible (A1 homozygote), heterozygote, and digestible (A2 homozygote). We compared these polymorphism distributions in both groups.

RESULT(S)

The percentage of genotypes D-G (TA, 13-16) in both groups were 10.5%, 29.4%, 13.0%, and 11.3% in group 1 and 7.9%, 16.7%, 19.9%, and 17.6% in group 2. The genotype E (14 TA repeats) is associated with a higher risk of endometriosis. Proportions of A1 homozygote/heterozygote/A2 homozygote for CYP17 were 26.1%/46.2%/27.7% for group 1 and 14.8%/44.5%/40.7% for group 2, respectively. The A1 homozygote and allele were associated with a higher susceptibility of endometriosis.

CONCLUSION(S)

ER alpha* 14 TA repeats and the CYP17* A1 allele are associated with an increased risk of endometriosis. Both polymorphisms are useful markers for predicting endometriosis susceptibility.

Polymorphisms of the genes encoding the GSTM1, GSTT1 and GSTP1 in Korean women: no association with endometriosis

Endometriosis, one of the most common gynaecologic disorders, shows significantly elevated prevalence in industrial areas and there is also a possible genetic predisposition. Glutathione-S-transferases (GSTs) are enzymes involved in the metabolism of many disease-causing carcinogens and mutagens that are present in human environments. An association between the incidence of endometriosis and the GST genotypes of patients has been suggested. The objective of the present study was to investigate whether the polymorphisms of GSTM1, GSTT1 and GSTP1 are related to endometriosis. Blood samples were available from 259 controls and 194 patients with advanced endometriosis diagnosed by both pathology and laparoscopic findings. The proportion of the GSTM1, GSTT1 and GSTP1 genotypes of the control group were comparable to other populations. There was no significant evidence that the distribution of the GSTM1 and GSTT1 genotype differed between the patients and the controls, with an allelic odds ratio (OR)=1.074 [95% confidence interval (CI)=0.737-1.564] and 1.239 (95% CI = 0.853-1.799), respectively. Also, there was no significant difference in the proportion of GSTP1 genotypes between the women with endometriosis and the control group with the OR = 0.823 (95% CI = 0.536-1.264). The higher risk alleles were contended as GSTM1, GSTT1 null mutation and GSTP1 Ile105Ile polymorphism. There was no significant increase in the risk of endometriosis as the number of higher risk alleles of the GST family increased. In conclusion, our findings suggest that the GSTM1, GSTT1 and GSTP1 genetic polymorphisms are not associated with the development of endometriosis in Korean women.

Androgen receptor gene cytosine, adenine, and guanine trinucleotide repeats in patients with endometriosis

OBJECTIVE

A genetic variation in the androgen receptor (AR) has been associated with the risk of developing endometriosis. The AR gene is located on the X chromosome and contains a highly polymorphic trinucleotide repeat (cytosine, adenine, and guanine: CAG) in its first exon, whose length and methylation pattern affect both AR expression and function. Thus, we sought to further investigate the potential association between endometriosis and the AR-CAG polymorphism.

METHODS

Genomic DNA was obtained from a consecutive series of 197 white Italian women of reproductive age who underwent laparoscopy for benign gynecologic pathologies. Molecular analysis of AR-CAG repeats was performed by polymerase chain reaction amplification and Genescan evaluation. The pattern of CAG repeat distribution was compared between subjects with and without endometriosis.

RESULTS

Endometriosis was documented in 105 women (stage I-II in 33 women and stage III-IV in 72 women). We found no difference in the number of AR-CAG repeats between women with endometriosis and controls. The CAG repeat length ranged from eight to 27 (mean +/- standard deviation, 17.4 +/- 1.9) for endometriosis patients and from 11 to 27 (mean +/- standard deviation, 17.4 +/- 2) for controls. Moreover, no association was found between AR gene polymorphisms and the various clinical manifestations of the disease.

CONCLUSION

We conclude that AR-CAG repeat length does not constitute an important factor for the genetic predisposition to endometriosis.

Glutathione S-transferase M1*null genotype but not myeloperoxidase promoter G-463A polymorphism is associated with higher susceptibility to endometriosis

Glutathione S-transferase M1 (GSTM1), one member of the GST family, is responsible for metabolism of xenobiotics and carcinogens. Myeloperoxidase (MPO) plays an important role in the oxidation and activation of carcinogens and nitric oxide. Allelic variants of GSTM1 and MPO gene polymorphisms might impair detoxification function and increase the susceptibility to endometriosis. We aimed to investigate if these polymorphisms are useful markers for predicting endometriosis susceptibility. Women were divided into two groups: (i) endometriosis (n=150); (ii) non-endometriosis (n=159). Polymorphisms for GSTM1 and MPO were amplified by polymerase chain reaction and detected by electrophoresis after restriction digestion. The relative frequencies of the GSTM1*wild (+/+,+/0)/null (0/0) genotypes and MPO-463*G/A gene polymorphisms between both groups were compared. The distribution of GSTM1 polymorphisms was significantly different between the two groups. Proportions of GSTM1*wild/null alleles in both groups were: (i) 36.7/63.3%; (ii) 95/5% (P=0.001). In contrast, MPO-463 genotypes were not significantly different between the two groups. Proportions of MPO*A homozygote/heterozygote/G homozygote in both groups were: (i) 2.7/17.4/79.9% and (ii) 1.9/17/81.1% (P> 0.05). We conclude that the GSTM1*null genotype is associated with a higher risk of endometriosis development. MPO-463*G/A gene polymorphism is not related to the susceptibility of endometriosis.

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

Estrogen plays a role in the pathogenesis of endometriosis. The CYP17 gene codes for the cytochrome P450c17alpha enzyme that is involved in the estrogen biosynthesis. We aimed to investigate if CYP17 polymorphism could be used as marker to predict the susceptibility of endometriosis. Women were divided into two groups: (1) severe endometriosis (n=119); (2) non-endometriosis groups (n=128). A 169-bp fragment encompassing the T/C polymorphic site in 5'-untranslated promoter region (5'-UTR) of the CYP17 was amplified by the polymerase chain reaction, treated with restriction enzyme MspA1I, and electrophoresis. The polymorphism was divided into restriction-enzyme indigestible (T homozygote), T/C heterozygote, and digestible (C homozygote). Genotypes and allelic frequencies for this polymorphism in both groups were compared. We observed a higher but non-significant percentage of T homozygote in the endometriosis women compared with the non-endometriosis women. Proportions of T homozygote / heterozygote / C homozygote for CYP17 in both groups were: (1) 26.1/46.2/27.7% and (2) 17.2/45.3/37.5% (p-value=0.131). T allele was related with higher susceptibility of endometriosis. T and C allele frequencies in both groups were: (1) 49.2/50.8%; (2) 39.8/60.2% (p-value=0.046). Despite the CYP17* T allele appearing to be associated with a trend of increased risk of endometriosis, CYP17 5'-UTR gene polymorphism might not be a useful marker for prediction of endometriosis susceptibility.