Identification of six loci associated with pelvic organ prolapse using genome-wide association analysis

4D DIA-PRM proteomic study identifying modulated pathways and biomarkers associated with pelvic organ prolapse

Pelvic organ prolapse (POP) is a highly disabling condition that negatively affects the quality of life of millions of women worldwide. However, the underlying mechanisms associated with the development and progression of the disease remain poorly understood. Here, an untargeted four-dimensional data-independent acquisition (4D DIA)-based proteomics approach was applied to vaginal wall tissue samples from POP (n = 19) and control (n = 8) patients to identify potential diagnostic biomarker(s) for POP and examine the molecular mechanisms underlying the disease. Of the 5713 tissue proteins that were detected, 1957 proteins were significantly changed in POP patients. Further bioinformatics analysis revealed that multiple biological processes including protein digestion & absorption, retrograde endocannabinoid signaling, tyrosine metabolism, and nucleotide metabolism were significantly enriched and associated with the pathogenesis of POP. Interestingly, 16 of these differentially expressed proteins associated with four pathways were also identified by targeted parallel reaction monitoring (PRM) proteomics analysis on the same 27 tissue samples. Changes in 94 % (15/16) of these proteins were consistent with the 4D DIA data. Furthermore, most proteins displayed good diagnostic accuracy with high area under the curve (AUC) values (AUC＞0.8). Specifically, five proteins including ELN, COL6A2, ENTPD1, AOC3, and COX7A2 distinguished between POP and control patients with very high accuracy (AUC ≥ 0.95) in both 4D DIA and PRM analyses, and may therefore be potential diagnostic biomarkers for POP. In summary, the present study not only provided several potential biomarker(s) for effective POP diagnosis, but extended our knowledge of the key regulatory pathways associated with the disease.

Association between the rs1036819 polymorphism of the ZFAT gene and pelvic organ prolapse: a case-control study

INTRODUCTION AND HYPOTHESIS

The identification of risk factors for pelvic organ prolapse (POP) would contribute to planning prevention strategies. This study tests the hypothesis that the rs1036819 polymorphism in the ZFAT gene is associated with POP and investigates other risk factors for prolapse development.

METHODS

A case-control study was carried out including 826 postmenopausal women divided into POP cases (stages III and IV) and controls (stages 0 and I), assessed by anamnesis, examination, and peripheral blood samples. DNA was extracted from blood and genotyped by real-time RT-PCR. We used logistic regression models for the association analyses of variables, with p < 0.05 for significance.

RESULTS

Five hundred and sixty-eight women were evaluated (315 POP and 253 controls). The minor allele C was found in 19.3% of our sample and the genotype frequencies of AA, AC, and CC were similar in both groups. Age (OR 1.09, 95% CI 1.06-1.13), number of pregnancies (OR 1.23, 95% CI 1.08-1.41), history of one vaginal delivery (OR 3.39, 95% CI 1.38-8.33) or two or more (OR 2.51, 95% CI 1.04-6.07), weight of the largest newborn (OR 1.0001, 95% CI 1-1.001), and family history of POP (OR 2.27, 95% CI 1.24-4.13) were independent risk factors for POP, whereas one cesarean section (OR 0.48, 95% CI 0.27-0.88) or two or more (OR 0.14, 95% CI 0.05-0.38) were protective.

CONCLUSIONS

No association was detected between the rs1036819 polymorphism of the ZFAT gene and advanced POP. Age, number of pregnancies, at least one vaginal delivery, weight of the newborn, and POP family history were independent risk factors for POP.

Potential molecular targets for intervention in pelvic organ prolapse

Pelvic organ prolapse (POP) is a concerning gynecological benign illness in middle-aged and senior women. Its etiology is complex, the incidence rate is high, symptoms are clinically subjective, and its influence tends to be polarized. At present, for those who need medical treatment, whether surgical or non-surgical, complications cannot be ignored, and treatment effect needs to be optimized. However, there is a lack of accurate molecular biological interventions for the prevention, diagnosis, progression delay, and treatment of POP. Here, we reviewed the current state of understanding of the molecular mechanisms and factors associated with POP etiology. These factors include cyclins, matrix metal peptidases/tissue inhibitors of metalloproteinases, microRNAs, homeobox A11, transforming growth factor β1, insulin-like growth factor 1, fibulin 5, lysyl oxidase-like 1, oxidative stress, inflammatory response, estrogen, and other potential biomarkers associated with POP. In addition, relevant molecular targets that may be used to intervene in POP are summarized. The aim of this review was to provide more information to identify accurate potential biomarkers and/or molecular targets for the prevention, diagnosis, progression delay, and treatment of POP, with the goal of improving medical treatment for patients at-risk for POP or having POP. Continued research is needed to identify additional details of currently accepted molecular mechanisms and to identify additional mechanisms that contribute to POP.

Interactions between genetic variants and environmental risk factors are associated with the severity of pelvic organ prolapse

OBJECTIVE

Both environmental and genetic risk factors contribute to pelvic organ prolapse (POP). No genome-wide study has investigated the gene-environment (G × E) interactions. In this study, we aim to identify single nucleotide polymorphisms (SNPs) that may interact with the potential environmental factors, maximum birth weight, and age in Chinese women.

METHODS

We recruited 576 women for phase 1 and 264 women for phase 2 with stages III and IV prolapse from six geographic regions of China. Genomic DNAs from blood samples were genotyped using Affymetrix Axiom Genome-Wide CHB1 Array of 640,674 SNPs for phase 1 and Illumina Infinium Asian Screening Array of 743,722 SNPs for phase 2. Meta-analysis was used to combine the two results. Interactions of genetic variants with maximum birth weight and age on POP severity were identified.

RESULTS

In phase 1, 502,283 SNPs in 523 women passed quality control and 450 women had complete POP-quantification measurements. In phase 2, 463,351 SNPs in 257 women passed quality control with complete POP-quantification measurements. Three SNPs rs76662748 ( WDR59 , Pmeta = 2.146 × 10 -8 ), rs149541061 ( 3p26.1 , Pmeta = 9.273 × 10 -9 ), and rs34503674 ( DOCK9 , Pmeta = 1.778 × 10 -9 ) respectively interacted with maximum birth weight, and two SNPs rs74065743 ( LINC01343 , Pmeta = 4.386 × 10 -8 ) and rs322376 ( NEURL1B - DUSP1 , Pmeta = 2.263 × 10 -8 ), respectively, interacted with age. The magnitude of disease severity associated with maximum birth weight and age differed according to genetic variants.

CONCLUSIONS

This study provided preliminary evidence that interactions between genetic variants and environmental risk factors are associated with POP severity, suggesting the potential use of combining epidemiologic exposure data with selected genotyping for risk assessment and patient stratification.

Molecular Landscape of Pelvic Organ Prolapse Provides Insights into Disease Etiology

Pelvic organ prolapse (POP) represents a major health care burden in women, but its underlying pathophysiological mechanisms have not been elucidated. We first used a case-control design to perform an exome chip study in 526 women with POP and 960 control women to identify single nucleotide variants (SNVs) associated with the disease. We then integrated the functional interactions between the POP candidate proteins derived from the exome chip study and other POP candidate molecules into a molecular landscape. We found significant associations between POP and SNVs in 54 genes. The proteins encoded by 26 of these genes fit into the molecular landscape, together with 43 other POP candidate molecules. The POP landscape is located in and around epithelial cells and fibroblasts of the urogenital tract and harbors four interacting biological processes-epithelial-mesenchymal transition, immune response, modulation of the extracellular matrix, and fibroblast function-that are regulated by sex hormones and TGFB1. Our findings were corroborated by enrichment analyses of differential gene expression data from an independent POP cohort. Lastly, based on the landscape and using vaginal fibroblasts from women with POP, we predicted and showed that metformin alters gene expression in these fibroblasts in a beneficial direction. In conclusion, our integrated molecular landscape of POP provides insights into the biological processes underlying the disease and clues towards novel treatments.

Pelvic Organ Prolapse

Pelvic organ prolapse (POP) is defined as the descent of one or more of the anterior and posterior vaginal walls, uterus (cervix), or apex of the vagina (vaginal vault or cuff scar after hysterectomy). Although POP can be asymptomatic, if the bulge extends beyond the opening of the vagina, it can have a significant impact on a woman's quality of life. Findings include vaginal bulging toward or through the vaginal introitus that the patient may feel, palpate, or see with a mirror. If a woman is bothered by her prolapse, she should be offered both nonsurgical and surgical treatments.

Genome-Wide Association Study of Pelvic Organ Prolapse Using the Michigan Genomics Initiative

OBJECTIVES

The aim of this study was to (1) replicate previously identified genetic variants significantly associated with pelvic organ prolapse and (2) identify new genetic variants associated with pelvic organ prolapse using a genome-wide association study.

METHODS

Using our institution's database linking genetic and clinical data, we identified 1,329 women of European ancestry with an International Classification of Diseases, Ninth Revision (ICD-9)/ICD-10 code for prolapse, 767 of whom also had Current Procedural Terminology (CPT)/ICD-9/ICD-10 procedure codes for prolapse surgery, and 16,383 women of European ancestry older than 40 years without a prolapse diagnosis code as controls. Patients were genotyped using the Illumina HumanCoreExome chip and imputed to the Haplotype Reference Consortium. We tested 20 million single nucleotide polymorphisms (SNPs) for association with pelvic organ prolapse adjusting for relatedness, age, chip version, and 4 principal components. We compared our results with 18 previously identified genome-wide significant SNPs from the UK Biobank, Commun Biol (2020;3:129), and Obstet Gynecol (2011;118:1345-1353).

RESULTS

No variants achieved genome-wide significance (P = 5 × 10-8). However, we replicated 4 SNPs with biologic plausibility at nominal significance (P ≤ 0.05): rs12325192 (P = 0.002), rs9306894 (P = 0.05), rs1920568 (P = 0.034), and rs1247943 (P = 0.041), which were all intergenic and nearest the genes SALL1, GDF7, TBX5, and TBX5, respectively.

CONCLUSIONS

Our replication of 4 biologically plausible previously reported SNPs provides further evidence for a genetic contribution to prolapse, specifically that rs12325192, rs9306894, rs1920568, and rs1247943 may contribute to susceptibility for prolapse. These and previously reported associations that have not yet been replicated should be further explored in larger, more diverse cohorts, perhaps through meta-analysis.

Systematic review and meta-analysis of genetic association studies of pelvic organ prolapse

INTRODUCTION AND HYPOTHESIS

Family and twin studies demonstrate that pelvic organ prolapse (POP) is heritable, but the genetic etiology is poorly understood. This review aimed to identify genetic loci and specific polymorphisms associated with POP, while assessing the strength, consistency, and risk of bias among reported associations.

METHODS

Updating an earlier systematic review, PubMed and HuGE Navigator as well as relevant conference abstracts were searched using genetic and phenotype keywords from 2015 to 2020. Screening and data extraction were performed in duplicate. Fixed and random effects meta-analyses were conducted using co-dominant models of inheritance. We assessed credibility of pooled associations using interim Venice criteria.

RESULTS

We screened 504 new abstracts and included 46 published and 7 unpublished studies. In pooled analyses we found significant associations for four polymorphisms: rs2228480 at the ESR1 gene (OR 0.67 95% CI 0.46-0.98, I² = 0.0%, Venice rating BAB), rs12589592 at the FBLN5 gene (OR 1.46 95% CI 1.11-1.82, I² = 36.3%, Venice rating BBB), rs484389 in the PGR gene (OR 0.61 95% CI 0.39-0.96, I² = 32.4%, Venice rating CBB), and rs1800012 at the COL1A1 gene (OR 0.80 95% CI 0.66-0.96, I² = 0.0%, Venice rating BAB). Further credible novel variants have also been recently identified in genome-wide association studies.

CONCLUSION

The genetic contributions to POP remain poorly understood. Several biologically plausible variants have been identified, but much work is required to establish the role of these genes in the pathogenesis of POP or to establish a role for genetic testing in clinical practice.

Collagen type 1A1, type 3A1, and LOXL1/4 polymorphisms as risk factors of pelvic organ prolapse

Objective

Collagen and elastin are the main components of the female pelvic tissue. We investigated whether single nucleotide polymorphisms (SNPs) of collagen type 1 alpha 1 (COL1A1), collagen type 3 alpha 1 (COL3A1), and lysyl oxidase-like (LOXL) 1 and 4 were associated with the onset of pelvic organ prolapse (POP) in Japanese women. Fifty-two women with POP and 28 women without POP were included. SNPs were identified using the TaqMan® SNP genotyping assay.

Results

Age, parity, and lower urinary tract symptoms were significantly higher in the POP group than in the control group. The prevalence of genotypes with rs2862296 polymorphism of LOXL4, an enzyme essential for extracellular matrix remodeling, was different between the POP (26.9% for GG, 51.9% for AG) and control groups (14.8% for GG, 33.3% for AG). However, polymorphisms of COL1A1, COL3A1, and LOXL1 were not related to the onset of POP. In the multivariate logistic regression analysis, age was significantly associated with the occurrence of POP. In the univariate analysis, LOXL4 polymorphism was associated with the onset of POP in Japanese women. The knowledge of acquired risk factors and polymorphisms in the genomic background of patients with POP may help prevent POP via early conservative interventions.

Modeling the Dependence Structure in Genome Wide Association Studies of Binary Phenotypes in Family Data

Genome-wide association studies (GWASs) are a popular tool for detecting association between genetic variants or single nucleotide polymorphisms (SNPs) and complex traits. Family data introduce complexity due to the non-independence of the family members. Methods for non-independent data are well established, but when the GWAS contains distinct family types, explicit modeling of between-family-type differences in the dependence structure comes at the cost of significantly increased computational burden. The situation is exacerbated with binary traits. In this paper, we perform several simulation studies to compare multiple candidate methods to perform single SNP association analysis with binary traits. We consider generalized estimating equations (GEE), generalized linear mixed models (GLMMs), or generalized least square (GLS) approaches. We study the influence of different working correlation structures for GEE on the GWAS findings and also the performance of different analysis method(s) to conduct a GWAS with binary trait data in families. We discuss the merits of each approach with attention to their applicability in a GWAS. We also compare the performances of the methods on the alcoholism data from the Minnesota Center for Twin and Family Research (MCTFR) study.

Family history and pelvic organ prolapse: a systematic review and meta-analysis

INTRODUCTION AND HYPOTHESIS

Numerous analytic observational studies assess family history as a risk factor for POP and report a wide range of associations. This review aims to systematically evaluate the role of family history of POP in relation to POP risk and its recurrence.

METHODS

A review was performed of the PubMed/MEDLINE database with search criteria specifying family history, risk factors, POP, and their synonyms as title/abstract keywords, as well as MESH terms, up to March 2020. We aggregated evidence across studies with fixed effects (FE) and random effects (RE) meta-analysis.

RESULTS

Forty-three articles underwent full-text review. Eighteen independent studies evaluating the relationship between family history of POP and POP risk in 3639 POP cases and 10,912 controls were eligible for meta-analysis. Four studies evaluating family history and POP recurrence in 224 recurrent cases and 400 non-recurrent cases were eligible for inclusion into another meta-analyses. A positive family history of POP is on average associated with 2.3- to 2.7-fold increased risk for POP (RE OR = 2.64; 95% CI = 2.07, 3.35) as well as a 1.4-fold increased risk for POP recurrence (FE OR = 1.44; 95% CI = 1.00, 2.08). Meta-analysis estimates of POP risk varied by study design, definition of family history, and model adjustment status. We found evidence that publication bias and recall bias are a possibility.

CONCLUSIONS

Family history of POP is a risk factor for both POP presence and recurrence. However, reported magnitudes may be overestimates due to confounding, recall bias, and publication bias.

Polymorphism on chromosome 20p13 near the IDH3B gene is associated with uterine prolapse

OBJECTIVES

Previous studies have found evidence for a genetic basis for pelvic organ prolapse (POP), but no genetic studies have differentiated between types of POP. This study investigated whether genetic variants in six previously suggested candidate loci for POP modify the risk of uterine prolapse (UP).

STUDY DESIGN

One hundred patients, aged 30-55 years, who had undergone surgery due to total UP and 105 healthy controls were included in this study. After extracting the genomic DNA from peripheral blood, six single nucleotide polymorphisms (SNPs) previously identified for POP were genotyped, and association analysis was performed for contributing risk factors. RNA expression was determined from sacrouterine ligaments of patients and controls using quantitative reverse transcription polymerase chain reaction.

RESULTS

The dominant genotype model for the T allele for SNP rs6051098 at the chromosome 20p13 locus was significant, and this remained significant with the risk factor regression model (p=0.046; odds ratio 1.93, 95 % confidence interval 1.01-3.66). The isocitrate dehydrogenase 3 beta (IDH3B) gene was the only potential candidate gene in the 20p13 locus that was significantly upregulated in sacrouterine biopsies in women with UP compared with controls (p = 0.034).

CONCLUSION

To the best of the authors' knowledge, this is the first study to show that genetic risk factors contribute to UP, and suggested rs6051098 as the best candidate risk factor associated with UP. According to expression data in sacrouterine tissue, this study suggests that the IDH3B gene plays a role in the pathogenesis of UP.

Genome-wide association identifies seven loci for pelvic organ prolapse in Iceland and the UK Biobank

Pelvic organ prolapse (POP) is a downward descent of one or more of the pelvic organs, resulting in a protrusion of the vaginal wall and/or uterus. We performed a genome-wide association study of POP using data from Iceland and the UK Biobank, a total of 15,010 cases with hospital-based diagnosis code and 340,734 female controls, and found eight sequence variants at seven loci associating with POP (P < 5 × 10-8); seven common (minor allele frequency >5%) and one with minor allele frequency of 4.87%. Some of the variants associating with POP also associated with traits of similar pathophysiology. Of these, rs3820282, which may alter the estrogen-based regulation of WNT4, also associates with leiomyoma of uterus, gestational duration and endometriosis. Rs3791675 at EFEMP1, a gene involved in connective tissue homeostasis, also associates with hernias and carpal tunnel syndrome. Our results highlight the role of connective tissue metabolism and estrogen exposure in the etiology of POP.

Genetic polymorphisms in collagen-related genes are associated with pelvic organ prolapse

OBJECTIVE

Pelvic organ prolapse (POP) is a common health issue that has a profound negative influence on women's quality of life. Genetic susceptibility to POP has been increasingly investigated. In this study, we assessed the single-nucleotide polymorphisms (SNPs) of six collagen-related genes (COL14A1, COL5A1, COL4A2, COL3A1, COL1A1, and COL18A1) and the genetic association with POP in Chinese women.

METHODS

We performed a candidate gene association study of case women (n = 48) with stage III and IV prolapse and control women (n = 48) without prolapse. A target region sequencing approach was used to identify the SNPs in collagen-related genes. The association between SNPs and POP was examined by Fisher exact tests for unadjusted model and logistic regression analysis adjusted for delivery and pregnancy.

RESULTS

There was a significant association between COL14A1 SNPs (rs4870723, rs2305600, and rs2305598; P = 0.013, 0.019, and 0.028, respectively), a COL5A1 SNP (rs3827852; P = 0.016), and COL4A2 SNPs (rs76425569, rs388222, and rs2281968; P = 0.049 for the three, and rs445348, P = 0.040) and POP, respectively. Although there was no significant association between the COL3A1 SNP and POP, there was a trend toward significance for COL14A1 SNP (rs2305603), COL4A2 SNP (rs74941798), two COL1A1 SNPs (rs2586488 and rs2249492) and three COL18A1 SNPs (rs1050351, rs56335679, and rs55690336), and POP.

CONCLUSION

We are the first to evaluate the relationship between COL14A1, COL5A1, and COL4A2 polymorphisms and POP, besides COL3A1, COL1A1, and COL18A1, which have been reported previously. We found several candidate SNPs that were significantly associated with prolapse in Chinese women. Our results provide new evidence for further investigation of the involvement of these potential genes in the etiology of POP.

Metabolomics study of serum and urine samples reveals metabolic pathways and biomarkers associated with pelvic organ prolapse

Pelvic organ prolapse (POP) is a common medical condition among women and involves complicated diagnostics and controversial surgical management. The exact molecular mechanism underlying POP is poorly understood, especially at the metabolism level. To explore the metabolic mechanism underlying POP and discover potential biomarkers for POP diagnosis, we applied a non-targeted metabolomics approach using ultra-high performance liquid chromatography coupled with quadrupole-time-of-flight mass spectrometry (UHPLC-Q-TOF-MS). Metabolomics study of serum samples from patients with POP (n = 24) and controls (n = 22) revealed a total of 59 metabolites that are significantly different (VIP ≥ 1 and p ≤ 0.05) between the two groups. Between urine samples from POP patients (n = 45) and controls (n = 59), 33 metabolites differed significantly (VIP ≥ 1 and p ≤ 0.05). Metabolic pathways affected by these differentially expressed metabolites were analyzed. In both serum and urine samples, three pathways including arginine biosynthesis and purine metabolism were found to be significantly related to POP. Six metabolites including GPC, 1-methyladenosine, maleic acid, L-pyroglutamic acid, inosine, and citrate are significantly changed (VIP ≥ 1 and p ≤ 0.05) in both serum and urine samples from patients with POP. Receiver operating characteristics (ROC) curve analysis showed that using these six metabolites as a biomarker could distinguish patients with POP from controls with good accuracy in both serum (AUC = 1) and urine samples (AUC = 0.854). Collectively, these results further extended our understanding of key regulatory metabolic pathways involved in the pathophysiology of POP, as well as provided some promising biomarkers for effective POP diagnosis.

Genome‑wide DNA methylation analysis of uterosacral ligaments in women with pelvic organ prolapse

Pelvic organ prolapse (POP) is an increasingly serious health problem that impairs quality of life and is caused by multiple additive genetic and environmental factors. As the uterosacral ligaments (ULs) provide primary support for the pelvic organs, it was hypothesized that disruption of these ligaments (as a result of aberrant methylation) may lead to a loss of support and eventually contribute to POP. In the present study, whether there are any aberrant methylations in the ULs of patients with POP compared to those of controls was investigated. Genomic DNA was isolated from the ULs of five women with POP and four women without POP, as controls, undergoing hysterectomy for benign conditions. An Illumina Infinium Methylation EPICBeadChips Infinium Human Methylation 850 K bead array was used to investigate the total methylation in the ULs. There were 3,723 differentially methylated CpG sites (Δβ<0.14; P<0.05), including 3,576 hypermethylation and 147 hypomethylation sites in the ULs of patients with POP compared with the normal controls. There were more hypermethylated CpG sites, but a high ratio of hypomethylation between CpG islands and the N-shelf; in the gene structure, there was more hypermethylation than hypomethylation in TSS1500 and the 5′ untranslated region. Gene ontology analysis demonstrated that these differentially methylated genes were associated with ‘cell morphogenesis’, ‘extracellular matrix’, ‘cell junction’, ‘protein binding’ and ‘guanosine triphosphatase activity’. Several significant pathways were identified, including ‘focal adhesion’ and ‘extracellular matrix-receptor interaction pathway’. This study provides evidence that there are differences in genome-wide DNA methylation between ULs in menopausal women with and without POP, and that epigenetic mechanisms may partly contribute to POP pathogenesis.

Genome-wide association study for variants that modulate relationships between cerebrospinal fluid amyloid-beta 42, tau, and p-tau levels

Background

A relationship quantitative trait locus exists when the correlation between multiple traits varies by genotype for that locus. Relationship quantitative trait loci (rQTL) are often involved in gene-by-gene (G×G) interactions or gene-by-environmental interactions, making them a powerful tool for detecting G×G.

Methods

We performed genome-wide association studies to identify rQTL between tau and Aβ42 and ptau and Aβ42 with over 3000 individuals using age, gender, series, APOE ε2, APOE ε4, and two principal components for population structure as covariates. Each significant rQTL was separately screened for interactions with other loci for each trait in the rQTL model. Parametric bootstrapping was used to assess significance.

Results

We found four significant tau/Aβ42 rQTL from three unique locations and six ptau/Aβ42 rQTL from five unique locations. G×G screens with these rQTL produced four significant G×G interactions (one Aβ42, two ptau, and one tau) with four rQTL where each second locus was from a unique location. On follow-up, rs1036819 and rs74025622 were associated with Alzheimer’s disease (AD) case/control status; rs15205 and rs79099429 were associated with rate of decline.

Conclusions

The two most significant rQTL (rs8027714 and rs1036819) for ptau/Aβ42 are on different chromosomes and both are strong hits for pelvic organ prolapse. While diseases of the nervous system can cause pelvic organ prolapse, it is unlikely related to the ptau/Aβ42 relationship but may suggest that these two loci share a pathway. In addition to a ptau/Aβ42 rQTL and association with AD case/control status, rs1036819 is a strong rQTL for case/control status/Aβ42 and for tau/Aβ42. It resides in the ZFAT gene, which is related to autoimmune thyroid disease. For tau, rs9817620 interacts with the tau/Aβ42 rQTL rs74025622. It is in the CHL1 gene, which is a neural cell adhesion molecule and may be involved in signal transduction pathways. CHL1 is related to BACE1, which is a β-secretase enzyme that initiates production of the β-amyloid peptide involved in AD and is a primary drug target. Overall, there are numerous loci that affect the relationship between these important AD endophenotypes and some are due to interactions with other loci. Some affect the risk of AD and/or rate of progression.

Electronic supplementary material

The online version of this article (10.1186/s13195-018-0410-y) contains supplementary material, which is available to authorized users.

A Variant of COL3A1 (rs3134646) Is Associated With Risk of Developing Diverticulosis in White Men

BACKGROUND

Colonic diverticulosis is one of the most common gastroenterological disorders. Although diverticulosis is typically benign, many individuals develop diverticulitis or other aspects of diverticular disease. Diverticulosis is thought to stem from a complex interaction of environmental, dietary, and genetic factors; however, the contributing genetic factors remain unknown.

OBJECTIVE

The aim of our present study was to determine the role of genetic variants within genes encoding for collagens of the connective tissue in diverticulosis.

DESIGN

This was a transsectional genetic association study.

SETTINGS

This study was conducted at three tertiary referral centers in Germany and Lithuania.

PATIENTS

Single-nucleotide polymorphisms in COL3A1 (rs3134646, rs1800255) and COL1A1 (rs1800012) were genotyped in 422 patients with diverticulosis and 285 controls of white descent by using TaqMan assays.

MAIN OUTCOME MEASURES

The association of colonoscopy-proven diverticulosis with genetic polymorphisms with herniations was assessed in multivariate models.

RESULTS

The rs3134646, rs1800255, and rs1800012 variants were significantly associated with the risk of developing diverticulosis in the univariate model; however, these associations were not significant in the multivariate logistic regression analysis including additional nongenetic variables. When selectively analyzing sexes, the genotype AA (AA) in rs3134646 remained significantly associated with diverticulosis in men (OR, 1.82; 95% CI, 1.04-3.20; p = 0.04).

LIMITATIONS

Because a candidate approach was used, additional relevant variants could be missed. Within our cohort of patients with diverticulosis, only a small proportion had diverticular disease and thus, we could not examine the variants in these subgroups. Functional studies, including the analysis of the involved collagens, are also warranted.

CONCLUSIONS

Our study shows that a variant of COL3A1 (rs3134646) is associated with the risk of developing colonic diverticulosis in white men, whereas rs1800255 (COL3A1) and rs1800012 (COL1A1) were not associated with this condition after adjusting for confounding factors. Our data provide novel valuable insights in the genetic susceptibility to diverticulosis. See Video Abstract at http://links.lww.com/DCR/A504.

Collagen XVIII and LOXL-4 polymorphisms in women with and without advanced pelvic organ prolapse

INTRODUCTION AND HYPOTHESIS

We verified the presence of single nucleotide polymorphisms (SNP) rs2236479 of the collagen 18 (COL18A1) and rs2862296 of the lysyl oxidase-like 4 (LOXL-4) genes and the association with pelvic organ prolapse (POP) in Brazilian women and determined risk factors for POP development.

METHODS

We assessed 532 postmenopausal women divided into POP (stages III and IV) and control (stages 0 and I) groups by examination and peripheral blood sample collection. DNA sequences of interest were analyzed by real-time reverse-transcriptase polymerase chain reaction (RT-PCR). We used logistic regression models for the analyses, with p < 0.005 for significance.

RESULTS

The frequency of homozygous polymorphic alleles (AA) in COL18A1 and (GG) in LOXL-4 were similar in both groups (17.5% and 15.4% for COL18A1 and 18.9% and 20.6% for LOXL-4, respectively). There were no associations between those polymorphisms or other genotypes and POP. Multiple logistic regression analysis identified age [odds ratio (OR) = 1.10, confidence interval (CI) 95% = 1.07; 1.14), number of vaginal births (OR = 1.66, CI 95% = 1.36; 2.03), and family history (OR = 2.55 CI 95% = 1.43; 4.55) as independent risk factors for POP.

CONCLUSION

Our study suggests lack of association between DNA polymorphisms rs2236479 of COL18A1 and rs2862296 of LOXL-4 with advanced POP in this population.

Admixture mapping of pelvic organ prolapse in African Americans from the Women's Health Initiative Hormone Therapy trial

Evidence suggests European American (EA) women have two- to five-fold increased odds of having pelvic organ prolapse (POP) when compared with African American (AA) women. However, the role of genetic ancestry in relation to POP risk is not clear. Here we evaluate the association between genetic ancestry and POP in AA women from the Women’s Health Initiative Hormone Therapy trial. Women with grade 1 or higher classification, and grade 2 or higher classification for uterine prolapse, cystocele or rectocele at baseline or during follow-up were considered to have any POP (N = 805) and moderate/severe POP (N = 156), respectively. Women with at least two pelvic exams with no indication for POP served as controls (N = 344). We performed case-only, and case-control admixture-mapping analyses using multiple logistic regression while adjusting for age, BMI, parity and global ancestry. We evaluated the association between global ancestry and POP using multiple logistic regression. European ancestry at the individual level was not associated with POP risk. Case-only and case-control local ancestry analyses identified two ancestry-specific loci that may be associated with POP. One locus (Chromosome 15q26.2) achieved empirically-estimated statistical significance and was associated with decreased POP odds (considering grade ≥2 POP) with each unit increase in European ancestry (OR: 0.35; 95% CI: 0.30, 0.57; p-value = 1.48x10^-5). This region includes RGMA, a potent regulator of the BMP family of genes. The second locus (Chromosome 1q42.1-q42.3) was associated with increased POP odds with each unit increase in European ancestry (Odds ratio [OR]: 1.69; 95% confidence interval [CI]: 1.28, 2.22; p-value = 1.93x10^-4). Although this region did not reach statistical significance after considering multiple comparisons, it includes potentially relevant genes including TBCE, and ACTA1. Unique non-overlapping European and African ancestry-specific susceptibility loci may be associated with increased POP risk.

Matrix Metalloproteinase-1 Expression in Women With and Without Pelvic Organ Prolapse: A Systematic Review and Meta-analysis

This meta‐analysis was conducted to estimate the association between matrix metalloproteinase‐1 (MMP‐1) expression and pelvic organ prolapse (POP) in women. Relevant studies published before 6 December 2015 were identified by searching PubMed, Ovid, EBSCO, and EMBASE. A total number of five case–control studies, including 182 POP cases and 192 controls, were identified. The results indicated that women without POP had a lower MMP‐1 level of expression compared with women with POP (odds ratio = 0.54, 95% confidence interval: 0.43–0.67, P = 0.000). After stratification by biopsy site, ethnicity, or menopausal status, this finding was also confirmed in the subgroup analysis with no significant changes. Egger's linear regression test revealed a potential publication bias (P = 0.028). The findings of our study indicate that women who suffer from POP have a higher expression level of MMP‐1 than women without POP.

Genetic Determinants of Pelvic Organ Prolapse among African American and Hispanic Women in the Women's Health Initiative

Current evidence suggests a multifactorial etiology to pelvic organ prolapse (POP), including genetic predisposition. We conducted a genome-wide association study of POP in African American (AA) and Hispanic (HP) women from the Women's Health Initiative Hormone Therapy study. Cases were defined as any POP (grades 1-3) or moderate/severe POP (grades 2-3), while controls had grade 0 POP. We performed race-specific multiple logistic regression analyses between SNPs imputed to 1000 genomes in relation to POP (grade 0 vs 1-3; grade 0 vs 2-3) adjusting for age at diagnosis, body mass index, parity, and genetic ancestry. There were 1274 controls and 1427 cases of any POP and 317 cases of moderate/severe POP. Although none of the analyses reached genome-wide significance (p<5x10-8), we noted variants in several loci that met p<10-6. In race-specific analysis of grade 0 vs 2-3, intronic SNPs in the CPE gene (rs28573326, OR:2.14; 95% CI 1.62-2.83; p = 1.0x10-7) were associated with POP in AAs, and SNPs in the gene AL132709.5 (rs1950626, OR:2.96; 95% CI 1.96-4.48, p = 2.6x10-7) were associated with POP in HPs. Inverse variance fixed-effect meta-analysis of the race-specific results showed suggestive signals for SNPs in the DPP6 gene (rs11243354, OR:1.36; p = 4.2x10-7) in the grade 0 vs 1-3 analyses and for SNPs around PGBD5 (rs740494, OR:2.17; p = 8.6x10-7) and SHC3 (rs2209875, OR:0.60; p = 9.3x10-7) in the grade 0 vs 2-3 analyses. While we did not identify genome-wide significant findings, we document several SNPs reaching suggestive statistical significance. Further interrogation of POP in larger minority samples is warranted.

Association of matrix metalloproteinase-10 polymorphisms with susceptibility to pelvic organ prolapse

AIM

The aim of this study was to explore the correlation between genetic mutations in matrix metalloproteinase-10 (MMP-10) and susceptibility to pelvic organ prolapse (POP).

MATERIAL AND METHODS

From September 2011 to December 2013, 263 subjects were recruited, including 91 patients with POP (case group) and 172 non-POP patients (control group). Total MMP-10 concentrations in serum were measured by enzyme-linked immunosorbent assay. The genotyping of MMP-10 was achieved by quantitative real-time polymerase chain reaction. All data were analyzed with SPSS 18.0.

RESULTS

We found that parity, menopause, history of total hysterectomy, and family history of POP were all significantly higher in the POP group than in the control group (P = 0.017, P = 0.046, P = 0.0029 and P < 0.001, respectively). Serum MMP-10 levels were obviously higher in the POP group than in the control group (P < 0.05). In addition, there was a statistically significant difference between the two groups in the distribution frequency of the MMP-10 (rs17435959G/C) genotype (P < 0.05). However, the distribution frequency of the MMP-10 (rs17293607C/T) genotype between the two groups showed no significant differences (P > 0.05). Furthermore, the patients with parity > 2 and postmenopausal women had elevated serum MMP-10 levels, and the patients with parity > 2 and postmenopausal women who carried the G/C + C/C genotype in the MMP-10 gene had an increased risk of POP.

CONCLUSION

We support the view that the rs17435959 polymorphism of the MMP-10 gene may be associated with an increased risk of POP.

Verification of the Chromosome Region 9q21 Association with Pelvic Organ Prolapse Using RegulomeDB Annotations

Pelvic organ prolapse (POP) is a common highly disabling disorder with a large hereditary component. It is characterized by a loss of pelvic floor support that leads to the herniation of the uterus in or outside the vagina. Genome-wide linkage studies have shown an evidence of POP association with the region 9q21 and six other loci in European pedigrees. The aim of our study was to test the above associations in a case-control study in Russian population. Twelve SNPs including SNPs cited in the above studies and those selected using the RegulomeDB annotations for the region 9q21 were genotyped in 210 patients with POP (stages III-IV) and 292 controls with no even minimal POP. Genotyping was performed using the polymerase chain reaction with confronting two-pair primers (PCR–CTPP). Association analyses were conducted for individual SNPs, 9q21 haplotypes, and SNP-SNP interactions. SNP rs12237222 with the highest RegulomeDB score 1a appeared to be the key SNP in haplotypes associated with POP. Other RegulomeDB Category 1 SNPs, rs12551710 and rs2236479 (scores 1d and 1f, resp.), exhibited epistatic effects. In this study, we verified the region 9q21 association with POP in Russians, using RegulomeDB annotations.

Evidence for pelvic organ prolapse predisposition genes on chromosomes 10 and 17

OBJECTIVE

We conducted a genomewide linkage analysis to identify pelvic organ prolapse (POP) predisposition genes using a resource of high-risk POP pedigrees.

STUDY DESIGN

Cases are defined as women who reported bothersome symptoms of POP based on standardized symptom questions (Pelvic Floor Distress Inventory, moderately or quite bothered), and/or received treatment for POP documented in medical records. Our complete pedigree resource contains 299 familial POP cases in 83 high-risk pedigrees. Genotype data were obtained from Illumina HumanHap550, 610Q, the Human1M-Duo, Human Omni1-Quad, or the Human Omni 2.5 platforms. A set of single nucleotide polymorphism markers common to all platforms was identified and markers in high linkage disequilibrium were removed. We performed a genomewide linkage analysis under general dominant and recessive models using a Markov chain, Monte Carlo linkage analysis method implemented in MCLINK (University of Utah) software. Because 70 individuals in 32 pedigrees were used in a previously published linkage analysis for a phenotype of POP requiring treatment/surgery, we also performed linkage only including the 225 newly recruited and genotyped cases in 61 pedigrees.

RESULTS

Linkage analysis using our complete pedigree resource for the loosened criteria of bothersome POP showed evidence for significant genomewide linkage on chromosome 10q24-26 (recessive model, maximum heterogeneity logarithm of odds 3.4); suggestive evidence was identified on chromosomes 6 and 17, and an additional region on chromosome 10. In the subset of only the newly recruited familial POP cases, significant evidence for genomewide linkage was observed on chromosome 17q25 (recessive model, maximum heterogeneity logarithm of odds 3.3), and suggestive evidence for linkage was observed on chromosomes 10 and 11. Neither analysis duplicated the previously published linkage evidence for the POP requiring treatment/surgery phenotype observed on chromosome 9.

CONCLUSION

While the etiology of this common condition is unknown, this study provides evidence that loci on chromosomes 10q and 17q may contribute to POP etiology.

Systematic review and metaanalysis of genetic association studies of urinary symptoms and prolapse in women

OBJECTIVE

Family studies and twin studies demonstrate that lower urinary tract symptoms and pelvic organ prolapse are heritable. This review aimed to identify genetic polymorphisms tested for an association with lower urinary tract symptoms or prolapse, and to assess the strength, consistency, and risk of bias among reported associations.

STUDY DESIGN

PubMed and HuGE Navigator were searched up to May 1, 2014, using a combination of genetic and phenotype key words, including "nocturia," "incontinence," "overactive bladder," "prolapse," and "enuresis." Major genetics, urology, and gynecology conference abstracts were searched from 2005 through 2013. We screened 889 abstracts, and retrieved 78 full texts. In all, 27 published and 7 unpublished studies provided data on polymorphisms in or near 32 different genes. Fixed and random effects metaanalyses were conducted using codominant models of inheritance. We assessed the credibility of pooled associations using the interim Venice criteria.

RESULTS

In pooled analysis, the rs4994 polymorphism of the ADRB3 gene was associated with overactive bladder (odds ratio [OR], 2.5; 95% confidence interval [CI], 1.7-3.6; n = 419). The rs1800012 polymorphism of the COL1A1 gene was associated with prolapse (OR, 1.3; 95% CI, 1.0-1.7; n = 838) and stress urinary incontinence (OR, 2.1; 95% CI, 1.4-3.2; n = 190). Other metaanalyses, including those for polymorphisms of COL3A1,LAMC1,MMP1,MMP3, and MMP9 did not show significant effects. Many studies were at high risk of bias from genotyping error or population stratification.

CONCLUSION

These metaanalyses provide moderate epidemiological credibility for associations of variation in ADRB3 with overactive bladder, and variation of COL1A1 with prolapse. Clinical testing for any of these polymorphisms cannot be recommended based on current evidence.

Genetic epidemiology of pelvic organ prolapse: a systematic review

Given current evidence supporting a genetic predisposition for pelvic organ prolapse, we conducted a systematic review of published literature on the genetic epidemiology of pelvic organ prolapse. Inclusion criteria were linkage studies, candidate gene association and genome-wide association studies in adult women published in English and indexed in PubMed through Dec. 2012, with no limit on date of publication. Methodology adhered to the PRISMA guidelines. Data were systematically extracted by 2 reviewers and graded by the Venice criteria for studies of genetic associations. A metaanalysis was performed on all single nucleotide polymorphisms evaluated by 2 or more studies with similar methodology. The metaanalysis suggests that collagen type 3 alpha 1 (COL3A1) rs1800255 genotype AA is associated with pelvic organ prolapse (odds ratio, 4.79; 95% confidence interval, 1.91-11.98; P = .001) compared with the reference genotype GG in populations of Asian and Dutch women. There was little evidence of heterogeneity for rs1800255 (P value for heterogeneity = .94; proportion of variance because of heterogeneity, I(2) = 0.00%). There was insufficient evidence to determine whether other single nucleotide polymorphisms evaluated by 2 or more papers were associated with pelvic organ prolapse. An association with pelvic organ prolapse was seen in individual studies for estrogen receptor alpha (ER-α) rs2228480 GA, COL3A1 exon 31, chromosome 9q21 (heterogeneity logarithm of the odds score 3.41) as well as 6 single nucleotide polymorphisms identified by a genome-wide association study. Overall, individual studies were of small sample size and often of poor quality. Future studies would benefit from more rigorous study design as outlined in the Venice recommendations.

Fibulin-5 (FBLN5) gene polymorphism is associated with pelvic organ prolapse

OBJECTIVE

FBLN5 encodes a key protein of elastic fiber matrix assembly and function that contributes to maintaining pelvic support and plays the important role in the pathophysiology of pelvic organ prolapse (POP). The aim of the study was to investigate whether there is an association between common single-nucleotide polymorphisms (SNPs) of the FBLN5 gene and POP.

STUDY DESIGN

A total of eleven tag SNPs of the FBLN5 gene were genotyped using the polymerase chain reaction with confronting two-pair primers (PCR-CTPP) in 210 patients with POP (stages III-IV) and 292 controls with no even minimal POP.

RESULTS

We revealed significant associations of tag SNPs rs2018736 and rs12589592 with POP. The top association signal was found for SNP rs2018736 (protective effect for the minor allele A) in the entire set: p=0.0026, OR=0.42, 95% CI: 0.24-0.75; in the stratum with pelvic floor trauma: p=0.0018, OR=0.27, 95% CI: 0.11-0.64; and in the stratum with fetal macrosomia: p=0.013, OR=0.14, 95% CI: 0.03-0.71. The results of the haplotype analyses were consistent with the single SNP analysis. In the strata without perineal trauma and fetal macrosomia effects were non-significant, possibly, due to the smaller effect sizes.

CONCLUSIONS

Current data provide, for the first time, strong evidence that common SNPs of the FBLN5 gene are associated with POP especially after pelvic floor injury.

Collagen type III alpha 1 polymorphism (rs1800255, COL3A1 2209 G>A) assessed with high-resolution melting analysis is not associated with pelvic organ prolapse in the Dutch population

INTRODUCTION AND HYPOTHESIS

The rs1800255, COL3A1 2209 G>A polymorphism in the alpha 1 chain of collagen type III has been associated with an increased risk of pelvic organ prolapse (POP). In one of our previous studies however, polymerase chain reaction-based restriction fragment length polymorphism (PCR-RFLP) misdiagnosed rs1800255, COL3A1 2209 G>A in 6 % of cases. The high-resolution melting (HRM) analysis on the contrary obtained a 100 % accordance for this specific polymorphism and was used in the present study to validate this risk factor for POP.

METHODS

In this case-control study, women with and without symptoms of POP were included and compared. DNA was extracted from blood samples. HRM analysis was used to assess for the presence of the homozygous rs1800255. Groups were compared using the Pearson chi-square, Mann-Whitney, and t tests. The discrepancy between HRM and PCR-RFLP results was investigated using PCR-RFLP results available from our previous study.

RESULTS

The study included 354 women: 272 patients with POP and 82 controls; 18 (7 %) cases versus 3 (4 %) controls had a homozygous rs1800255, COL3A1 2209 G>A polymorphism (odds ratio 1.9, 95 % confidence interval 0.5-6.9, compared to the wild type), and thus no association between POP and the homozygous polymorphism could be demonstrated. A discrepancy between HRM and PCR-RFLP results was found in 8 % of the samples.

CONCLUSIONS

The previously found statistically significant association between the rs1800255, COL3A1 2209 G>A polymorphism as measured with PCR-RFLP and POP could no longer be demonstrated. This raises concerns regarding the results of other association studies using PCR-RFLP.

Recent studies of genetic dysfunction in pelvic organ prolapse: the role of collagen defects

Gynaecologists are becoming increasingly aware that women with a family history of prolapse are at an increased risk of prolapse refractory to treatment. In the past five years, several genetic mutations have been shown to correlate with increased prolapse susceptibility. These mutations can result in disordered collagen metabolism, which weaken the fascial support of the pelvic organs. This review examines the contemporary evidence regarding the role of collagen in prolapse.

Phenotyping clinical disorders: lessons learned from pelvic organ prolapse

Genetic epidemiology, the study of genetic contributions to risk for disease, is an innovative area in medicine. Although research in this arena has advanced in other disciplines, few genetic epidemiological studies have been conducted in obstetrics and gynecology. It is crucial that we study the genetic susceptibility for issues in women's health because this information will shape the new frontier of personalized medicine. To date, preterm birth may be one of the best examples of genetic susceptibility in obstetrics and gynecology, but many areas are being evaluated including endometriosis, fibroids, polycystic ovarian syndrome, and pelvic floor disorders. An essential component to genetic epidemiological studies is to characterize, or phenotype, the disorder to identify genetic effects. Given the growing importance of genomics and genetic epidemiology, we discuss the importance of accurate phenotyping of clinical disorders and highlight critical considerations and opportunities in phenotyping, using pelvic organ prolapse as a clinical example.

Matrix metalloproteinase-9 genetic polymorphisms and the risk for advanced pelvic organ prolapse

OBJECTIVE

Matrix metalloproteinase-9 (MMP9) is a protease associated with degradation of collagen and elastin. Because increased MMP9 activity in vaginal tissue has been associated with pelvic organ prolapse (POP), we sought to comprehensively estimate MMP9 genetic variants and the risk for advanced prolapse.

METHODS

This is a candidate gene association study of women with stage III-IV prolapse (case group, n=239) and women with stage 0-1 prolapse (control group, n=197). We attempted to oversample "extreme" phenotypes, including younger women with severe prolapse and older women without prolapse, in an attempt to concentrate the genetic effect. We used a linkage disequilibrium tagged approach to identify single nucleotide polymorphisms in MMP9 to evaluate in our study. To minimize potential confounding by race, our analysis focused on non-Hispanic white women. We performed multivariable logistic regression to estimate the association between MMP9 single nucleotide polymorphisms and case-control status, adjusting for age and vaginal parity.

RESULTS

Women with advanced prolapse were slightly younger (64.8 ± 10.3 compared with 69.0 ± 10.2 years, P<.001) and more likely to have had one or more vaginal deliveries (96.6% compared with 82.2%, P<.001) when compared with control participants. Eight single nucleotide polymorphisms were assessed, which represented 93% coverage of the MMP9 gene. Of these, two were associated with advanced prolapse: 1) rs3918253 (adjusted odds ratio [OR] 0.64, 95% confidence interval [CI] 0.41-1.0, P=.05); and 2) rs3918256 (adjusted OR 0.64, 95% CI 0.41-1.01, P=.05).

CONCLUSION

MMP9 is a biologically plausible candidate gene for POP given our results.

Characterizing the phenotype of advanced pelvic organ prolapse

OBJECTIVE

Genetic studies require a clearly defined phenotype to reach valid conclusions. Our aim was to characterize the phenotype of advanced prolapse by comparing women with stage III to IV prolapse with controls without prolapse.

METHODS

Based on the pelvic organ prolapse quantification examination, women with stage 0 to stage I prolapse (controls) and those with stage III to stage IV prolapse (cases) were prospectively recruited as part of a genetic epidemiologic study. Data regarding sociodemographics; medical, obstetric, and surgical history; family history; and body mass index were obtained by a questionnaire administered by a trained coordinator and abstracted from electronic medical records.

RESULTS

There were 275 case patients with advanced prolapse and 206 controls with stage 0 to stage I prolapse. Based on our recruitment strategy, the women were younger than the controls (64.7 ± 10.1 vs 68.6 ± 10.4 years; P<0.001); cases were also more likely to have had one or more vaginal deliveries (96.0% vs 82.0%; P<0.001). There were no differences in race, body mass index, and constipation. Regarding family history, cases were more likely to report that either their mother and/or sister(s) had prolapse (44.8% vs 16.9%, P<0.001). In a logistic regression model, vaginal parity (odds ratio, 4.05; 95% confidence interval, 1.67-9.85) and family history of prolapse (odds ratio, 3.74; 95% confidence interval, 2.16-6.46) remained significantly associated with advanced prolapse.

CONCLUSIONS

Vaginal parity and a family history of prolapse are more common in women with advanced prolapse compared to those without prolapse. These characteristics are important in phenotyping advanced prolapse, suggesting that these data should be collected in future genetic epidemiologic studies.