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Genome-wide association (GWA) studies have identified 19 independent common risk loci for endometriosis. Most of the GWA variants are non-coding and the genes responsible for the association signals have not been identified. Herein, we aimed to assess the potential role of protein-modifying variants in endometriosis using exome-array genotyping in 7164 cases and 21005 controls, and a replication set of 1840 cases and 129016 controls of European ancestry. Results in the discovery sample identified significant evidence for association with coding variants in single-variant (rs1801232-CUBN) and gene-level (CIITA and PARP4) meta-analyses, but these did not survive replication. In the combined analysis, there was genome-wide significant evidence for rs13394619 (P = 2.3 × 10-9) in GREB1 at 2p25.1 - a locus previously identified in a GWA meta-analysis of European and Japanese samples. Despite sufficient power, our results did not identify any protein-modifying variants (MAF > 0.01) with moderate or large effect sizes in endometriosis, although these variants may exist in non-European populations or in high-risk families. The results suggest continued discovery efforts should focus on genotyping large numbers of surgically-confirmed endometriosis cases and controls, and/or sequencing high-risk families to identify novel rare variants to provide greater insights into the molecular pathogenesis of the disease.

Endometriosis is a heritable hormone-dependent gynecological disorder, associated with severe pelvic pain and reduced fertility; however, its molecular mechanisms remain largely unknown. Here we perform a meta-analysis of 11 genome-wide association case-control data sets, totalling 17,045 endometriosis cases and 191,596 controls. In addition to replicating previously reported loci, we identify five novel loci significantly associated with endometriosis risk (P

Abstract Background Endometriosis is associated with chronic subclinical inflammation. C-reactive protein (CRP), a marker of inflammation, could serve as a biomarker of endometriosis. We tested the hypothesis that a high sensitivity CRP assay (hsCRP) is more accurate than a classical CRP assay in the detection of subclinical inflammation in plasma of women with endometriosis. Methods CRP levels were measured by hsCRP and classical CRP assays in plasma of 204 women with endometriosis and 91 women without endometriosis. Both assays were compared with respect to their value for the diagnosis of endometriosis. Results The number of plasma samples with detectable CRP was significantly higher (100%) using the hsCRP assay when compared to the classical CRP assay (42.7%) (p < 0.0001). Significantly increased CRP plasma levels were found in women with endometriosis when compared with controls when the hsCRP assay was used in samples obtained during the luteal phase (p = 0.008). The highest discriminative ability for the diagnosis of endometriosis was also obtained using the hsCRP assay during the luteal phase, especially for moderate -severe endometriosis. At a cut-off level of hsCRP > 0.71 mg/L, moderate-severe stages were diagnosed with 80.7% sensitivity and 63.9% specificity during the luteal phase. Using a similar cut-off value for CRP analyzed by the classical method, moderate-severe endometriosis was diagnosed with lower sensitivity (67.7%, p = 0.06) and comparable specificity (63.9%). Conclusions The hsCRP assay was superior to the classical CRP assay for the detection of low CRP levels and for revealing subclinical inflammation in plasma of women with endometriosis.

Abstract Background According to mRNA microarray, proteomics and other studies, biological abnormalities of eutopic endometrium (EM) are involved in the pathogenesis of endometriosis, but the relationship between mRNA and protein expression in EM is not clear. We tested for the first time the hypothesis that EM TRIzol extraction allows proteomic Surface Enhanced Laser Desorption/Ionisation Time-of-Flight Mass Spectrometry (SELDI-TOF MS) analysis and that these proteomic data can be related to mRNA (microarray) data obtained from the same EM sample from women with and without endometriosis. Methods Proteomic analysis was performed using SELDI-TOF-MS of TRIzol-extracted EM obtained during secretory phase from patients without endometriosis (n = 6), patients with minimal-mild (n = 5) and with moderate-severe endometriosis (n = 5), classified according to the system of the American Society of Reproductive Medicine. Proteomic data were compared to mRNA microarray data obtained from the same EM samples. Results In our SELDI-TOF MS study 32 peaks were differentially expressed in endometrium of all women with endometriosis (stages I-IV) compared with all controls during the secretory phase. Comparison of proteomic results with those from microarray revealed no corresponding genes/proteins. Conclusion TRIzol treatment of secretory phase EM allows combined proteomic and mRNA microarray analysis of the same sample, but comparison between proteomic and microarray data was not evident, probably due to post-translational modifications.

Evidence from observational studies indicates that endometriosis and depression often co-occur. However, conflicting evidence exists, and the etiology as well as biological mechanisms underlying their comorbidity remain unknown. Utilizing genome-wide association study (GWAS) data, we comprehensively assessed the relationship between endometriosis and depression. Single nucleotide polymorphism effect concordance analysis (SECA) found a significant genetic overlap between endometriosis and depression (PFsig-permuted = 9.99 × 10−4). Linkage disequilibrium score regression (LDSC) analysis estimated a positive and highly significant genetic correlation between the two traits (rG = 0.27, P = 8.85 × 10−27). A meta-analysis of endometriosis and depression GWAS (sample size = 709,111), identified 20 independent genome-wide significant loci (P < 5 × 10−8), of which eight are novel. Mendelian randomization analysis (MR) suggests a causal effect of depression on endometriosis. Combining gene-based association results across endometriosis and depression GWAS, we identified 22 genes with a genome-wide significant Fisher's combined P value (FCPgene < 2.75 × 10−6). Genes with a nominal gene-based association (Pgene < 0.05) were significantly enriched across endometriosis and depression (Pbinomial-test = 2.90 × 10−4). Also, genes overlapping the two traits at Pgene < 0.1 (Pbinomial-test = 1.31 × 10−5) were significantly enriched for the biological pathways 'cell–cell adhesion', 'inositol phosphate metabolism', 'Hippo-Merlin signaling dysregulation' and 'gastric mucosa abnormality'. These results reveal a shared genetic etiology for endometriosis and depression. Indeed, additional analyses found evidence of a causal association between each of endometriosis and depression and at least one abnormal condition of gastric mucosa. Our study confirms the comorbidity of endometriosis and depression, implicates links with gastric mucosa abnormalities in their causal pathways and reveals potential therapeutic targets for further investigation. [ABSTRACT FROM AUTHOR]

Background: Endometriosis is a common disorder that affects 6-10% of reproductive age women. In a previous study, we demonstrated that a polymorphism in let-7 microRNA-binding site in the 3' untranslated region of the KRAS gene was found in 31% of subjects with endometriosis resistant to medical therapy. This polymorphism was now tested in a large, case-control study.Methods: Peripheral blood or peritoneal biopsies from 2,077 European subjects with or without endometriosis and known infertility were tested for the presence of the variant allele using polymerase chain reaction.Results: Histologically proven endometriosis was found in 1,140 subjects, while 937 subjects were disease free. Variant allele carrier rates in subjects with and without endometriosis were 15.7 and 15.1%, respectively. No association between the variant KRAS allele and stage of the disease, age at surgery, body mass index, or type of infertility was identified.Conclusion: A germ-line single-nucleotide polymorphism in the let-7 microRNA-binding site of the KRAS gene was not associated with sporadic endometriosis in an infertile Caucasian population in this large case-control study. However, it remains possible that this gene variant may be a marker of treatment resistance. Further studies on the role of this polymorphism in endometriosis are needed. [ABSTRACT FROM AUTHOR]

Myeloperoxidase (MPO) is a proinflammatory enzyme and a marker for neutrophil activation and oxidative stress. Since oxidative stress and inflammation are linked to the pathogenesis of endometriosis, we hypothesized that the total, active, and specific (active/total) MPO levels were significantly different in plasma of women with and without endometriosis. Samples were selected from our biobank from women with endometriosis (n = 212) and controls without endometriosis (n = 121) across the menstrual cycle. Total MPO plasma levels were measured by immunoassay and MPO activity by enzymatic assay. Total and active MPO levels did not differ significantly among endometriosis cases and controls, whereas the specific MPO activity was significantly lower in women with endometriosis than that in controls (p = 0.0159). After the subdivision of control patients into women with a normal pelvis and women with other benign gynecological disorders, a significant difference was observed only between women with endometriosis and women with other benign gynecological disorders (p = 0.0266). In conclusion, systemic MPO levels may not be suited as a single biomarker for endometriosis. Our data support the involvement of MPO in other gynecological disorders but do not provide any evidence for an association with endometriosis. [ABSTRACT FROM AUTHOR]

To reinforce Sampson’s theory of retrograde menstruation in the pathogenesis of endometriosis, proof should be provided that during menstruation endometrial cells are present in peritoneal fluid (PF). We hypothesize that the prevalence of PF samples containing endometrial cells is higher in patients with endometriosis than in controls without endometriosis during menstruation. We selected from our biobank PF samples of 17 reproductive-age women with (n = 9) or without (n = 8) endometriosis who had received a diagnostic laparoscopy for investigation of pain/infertility. Peritoneal fluid had been collected during laparoscopy in the menstrual phase of the cycle, centrifuged, and the resulting pellet was stored at −80°C. About 5-μm sections of frozen PF pellets were stained using the Dako Envision Flex system with primary antibodies against epithelial cell adhesion molecule (Ep-CAM; endometrial epithelial cells), CD10 (endometrial stromal cells), prekeratin (epithelial/mesothelial cells), vimentin (endometrial/mesothelial/immune cells), calretinin (mesothelial cells), and CD68 (macrophages). The PF cells positive for Ep-CAM were detected in 5 of 9 patients with endometriosis and 6 of 8 controls (P = .62). CD10 stained positively in 6 of the 9 patients with endometriosis and 3 of the 8 controls (P = .35). Calretinin and prekeratin staining showed the presence of mesothelial cells in all pellets. Vimentin stained approximately 100% of the PF cells. CD68+ macrophages represented >50% of cells in all pellets. The prevalence of PF samples containing endometrial epithelial and stromal cells was not higher in patients with endometriosis than in controls without endometriosis during menstruation. Our findings question the relevance of endometrial cells in PF for the pathogenesis of endometriosis and support the importance of other mechanisms such as immune dysfunction and/or endometrial stem cells. [ABSTRACT FROM AUTHOR]