African ancestry and genetic risk for uterine leiomyomata

Bipedalism and the dawn of uterine fibroids

The high prevalence and burden of uterine fibroids in women raises questions about the origin of these benign growths. Here, we propose that fibroids should be understood in the context of human evolution, specifically the advent of bipedal locomotion in the hominin lineage. Over the ≥7 million years since our arboreal ancestors left their trees, skeletal adaptations ensued, affecting the pelvis, limbs, hands, and feet. By 3.2 million years ago, our ancestors were fully bipedal. A key evolutionary advantage of bipedalism was the freedom to use hands to carry and prepare food and create and use tools which, in turn, led to further evolutionary changes such as brain enlargement (encephalization), including a dramatic increase in the size of the neocortex. Pelvic realignment resulted in narrowing and transformation of the birth canal from a simple cylinder to a convoluted structure with misaligned pelvic inlet, mid-pelvis, and pelvic outlet planes. Neonatal head circumference has increased, greatly complicating parturition in early and modern humans, up to and including our own species. To overcome the so-called obstetric dilemma provoked by bipedal locomotion and encephalization, various compensatory adaptations have occurred affecting human neonatal development. These include adaptations limiting neonatal size, namely altricial birth (delivery of infants at an early neurodevelopmental stage, relative to other primates) and mid-gestation skeletal growth deceleration. Another key adaptation was hyperplasia of the myometrium, specifically the neomyometrium (the outer two-thirds of the myometrium, corresponding to 90% of the uterine musculature), allowing the uterus to more forcefully push the baby through the pelvis during a lengthy parturition. We propose that this hyperplasia of smooth muscle tissue set the stage for highly prevalent uterine fibroids. These fibroids are therefore a consequence of the obstetric dilemma and, ultimately, of the evolution of bipedalism in our hominin ancestors.

Research on Health Disparities: Strategies and Findings From the Black Women's Health Study

The American Journal of Epidemiology has been a platform for findings from the Black Women's Health Study (BWHS) that are relevant to health disparities. Topics addressed have included methods of follow-up of a large cohort of Black women, disparities in health-care delivery, modifiable risk factors for health conditions that disproportionately affect Black women, associations with exposures that are highly prevalent in Black women, and methods for genetic research. BWHS papers have also highlighted the importance of considering social context, including perceived experiences of racism, in understanding health disparities. In the future, BWHS investigators will contribute to documentation of the role that structural racism plays in health disparities.

Validation of self-report of uterine fibroid diagnosis using a transvaginal ultrasound scan

Self-report of uterine fibroids (UF) has been used for epidemiologic research in different environments. Given the dearth of studies on the epidemiology of UF in Sub-Saharan Africa (SSA), it is valuable to evaluate its performance as a potential tool for much needed research on this common neoplasm in SSA women. We conducted a cross-sectional study of self-report of UF compared with transvaginal ultrasound diagnosis (TVUS) among 486 women who are members of the African Collaborative Center for Microbiome and Genomics Research (ACCME) Study Cohort in central Nigeria. We used log-binomial regression models to compute the classification, sensitivity, specificity, and predictive values of self-report compared to TVUS, adjusted for significant covariates. The prevalence of UF on TVUS was 45.1% (219/486) compared to 5.4% (26/486) based on self-report of abdominal ultrasound scan and 7.2% (35/486) based on report of healthcare practitioner's diagnosis. Self-report correctly classified 39.5% of the women compared to TVUS in multivariable adjusted models. The multivariable adjusted sensitivity of self-report of healthcare worker diagnosis was 38.8%, specificity was 74.5%, positive predictive value (PPV) was 55.6%, and negative predictive value (NPV) was 59.8%. For self-reported abdominal ultrasound diagnosis, the multivariable adjusted sensitivity was 40.6%, specificity was 75.3%, PPV was 57.4%, and NPV was 60.6%. Self-report significantly underestimates the prevalence of UF and is not accurate enough for epidemiological research on UF. Future studies of UF should use population-based designs and more accurate diagnostic tools such as TVUS.

A heterozygous missense variant in DLX3 leads to uterine leiomyomas and pregnancy losses in a consanguineous Iranian family

Uterine leiomyomas (ULs) are benign solid tumors arising from the uterine myometrium. They are the most common pelvic tumors among females of reproductive age. Despite the universal prevalence of ULs and its huge impact on women's lives, the exact etiology and pathophysiologic mechanisms have not been fully understood. Numerous studies indicate that genetic factors play a crucial role in ULs development. This study aims to identify the probable genetic causes of ULs in a consanguineous Iranian family. Whole-exome sequencing (WES) on five family members with ULs revealed a likely pathogenic missense variant encoding for Y88C in the transactivation (TA) domain of DLX3 gene (c.263A > G; p.Y88C). Sanger sequencing of a total of 9 affected and non-affected family members indicated a segregation with disease with autosomal dominant inheritance. Moreover, targeted Sanger sequencing on 32 additional non-related patients with ULs showed none was heterozygous for this variant. MutPred2 predicted the pathogenicity of candidate variant by both phosphorylation and sulfation loss as actionable hypotheses. Project HOPE revealed that the identified variant residue is smaller and more hydrophobic comparing to the wild-type residue. I-TASSER and UCSF Chimera were also used for modeling and visualizing the predicted variant, respectively. This WES analysis is the first to report a variant in DLX3 variation associated with ULs pathogenicity in Iranian population highlighting the effectiveness of WES as a strong diagnostic method. However, further functional studies on this variant are needed to confirm the potential pathogenicity of this mutation.

Inherited mutations affecting the SRCAP complex are central in moderate-penetrance predisposition to uterine leiomyomas

Uterine leiomyomas (ULs) are benign smooth muscle tumors that are common in premenopausal women. Somatic alterations in MED12, HMGA2, FH, genes encoding subunits of the SRCAP complex, and genes involved in Cullin 3-RING E3 ligase neddylation are mutually exclusive UL drivers. Established predisposition genes explain only partially the estimated heritability of leiomyomas. Here, we examined loss-of-function variants across 18,899 genes in a cohort of 233,614 White European women, revealing variants in four genes encoding SRCAP complex subunits (YEATS4, ZNHIT1, DMAP1, and ACTL6A) with a significant association to ULs, and YEATS4 and ZNHIT1 strikingly rank first and second, respectively. Positive mutation status was also associated with younger age at diagnosis and hysterectomy. Moderate-penetrance UL risk was largely attributed to rare non-synonymous mutations affecting the SRCAP complex. To examine this disease phenotype more closely, we set out to identify inherited mutations affecting the SRCAP complex in our in-house sample collection of Finnish individuals with ULs (n = 860). We detected one individual with an ACTL6A splice-site mutation, two individuals with a YEATS4 missense mutation, and four individuals with DMAP1 mutations: one splice-site, one nonsense, and two missense variants. These individuals had large and/or multiple ULs, were often diagnosed at an early age, and many had family history of ULs. When a somatic second hit was found, ACTL6A and DMAP1 were silenced in tumors by somatic mutation and YEATS4 by promoter hypermethylation. Decreased H2A.Z staining was observed in the tumors, providing further evidence for the pathogenic nature of the germline mutations. Our results establish inactivation of genes encoding SRCAP complex subunits as a central contributor to moderate-penetrance UL predisposition.

Evidence of a causal effect of genetic tendency to gain muscle mass on uterine leiomyomata

Uterine leiomyomata (UL) are the most common tumours of the female genital tract and the primary cause of surgical removal of the uterus. Genetic factors contribute to UL susceptibility. To add understanding to the heritable genetic risk factors, we conduct a genome-wide association study (GWAS) of UL in up to 426,558 European women from FinnGen and a previous UL meta-GWAS. In addition to the 50 known UL loci, we identify 22 loci that have not been associated with UL in prior studies. UL-associated loci harbour genes enriched for development, growth, and cellular senescence. Of particular interest are the smooth muscle cell differentiation and proliferation-regulating genes functioning on the myocardin-cyclin dependent kinase inhibitor 1 A pathway. Our results further suggest that genetic predisposition to increased fat-free mass may be causally related to higher UL risk, underscoring the involvement of altered muscle tissue biology in UL pathophysiology. Overall, our findings add to the understanding of the genetic pathways underlying UL, which may aid in developing novel therapeutics.

Uterine Weight as a Modifier of Black/White Racial Disparities in Minimally Invasive Hysterectomy Among Veterans with Fibroids in the Veterans Health Administration

Introduction

Uterine fibroids are the most common indication for hysterectomy. Minimally invasive hysterectomy (MIH) confers lower risk of complications and shorter recovery than open surgical procedures; however, it is more challenging to perform with larger fibroids. There are racialized differences in fibroid size and MIH rates. We examined the role of uterine size in black-white differences in MIH among Veterans in the Department of Veterans Affairs (VA).

Methods

Using VA clinical and administrative data, we conducted a cross-sectional study among black and white Veterans with fibroids who underwent hysterectomy between 2012 and 2014. We abstracted postoperative uterine weight from pathology reports as a proxy for uterine size. We used a generalized linear model to estimate the association between race and MIH and tested an interaction between race and postoperative uterine weight (≤250 g vs. >250 g). We estimated adjusted marginal effects for racial differences in MIH by postoperative uterine weight.

Results

The sample included 732 Veterans (60% black, 40% white). Postoperative uterine weight modified the association of race and MIH (p for interaction=0.05). Black Veterans with postoperative uterine weight ≤250 g had a nearly 12-percentage point decrease in MIH compared to white Veterans (95% CI -23.1 to -0.5), with no difference by race among those with postoperative uterine weight >250 g.

Discussion

The racial disparity among Veterans with small fibroids who should be candidates for MIH underscores the role of other determinants beyond uterine size. To eliminate disparities in MIH, research focused on experiences of black Veterans, including pathways to treatment and provider-patient interactions, is needed.

Transcriptome and DNA methylome analyses reveal underlying mechanisms for the racial disparity in uterine fibroids

Uterine fibroids (leiomyomas) affect Black women disproportionately compared with women of other races and ethnicities in terms of prevalence, incidence, and severity of symptoms. The causes of this racial disparity are essentially unknown. We hypothesized that myometria of Black women are more susceptible to developing fibroids, and we examined the transcriptomic and DNA methylation profiles of myometria and fibroids from Black and White women for comparison. Myometrial samples cluster by race in both their transcriptome and DNA methylation profiles, whereas fibroid samples only cluster by race in the latter. More differentially expressed genes (DEGs) were detected in the Black and White myometrial sample comparison than in the fibroid comparison. Leiomyoma gene set expression analysis identified 4 clusters of DEGs, including a cluster of 24 genes with higher expression in myometrial samples from Black women. One of the DEGs in this group, von Willibrands factor (VWF), was significantly hypomethylated in both myometrial samples from Black women and in all fibroids at 2 CpG probes that are near a putative enhancer site and that are correlated with VWF expression levels. These results suggest that the molecular basis for the disparity in fibroid disease between Black and White women could be found in the myometria before fibroid development and not in the fibroids themselves.

Natural history of fibroids in pregnancy: National Institute of Child Health and Human Development Fetal Growth Studies - Singletons cohort

OBJECTIVE

To describe the natural history of fibroids in pregnancy in a racially diverse cohort and explore whether fibroid changes were associated with participant characteristics.

DESIGN

Prospective cohort study.

SETTING

Twelve clinical sites.

PATIENT(S)

Pregnant women (n = 2774; 27% non-Hispanic White, 28% non-Hispanic Black, 29% Hispanic, 17% Asian/Pacific Islander) who had up to 6 obstetric ultrasounds in gestational weeks 10-41.

INTERVENTION(S)

Sonographers recorded fibroid number and volume of the 3 largest fibroids at each visit. Generalized linear mixed models estimated the trajectories of fibroid number and total volume (overall and stratified by total volume at first visualization: equivalent to a fibroid of <1 cm [small], 1 to <3 cm [medium], or ≥3 cm [large] in diameter). We tested the interactions between the trajectories and race/ethnicity, age (<26, 26-30, 31-34, and ≥35 years), body mass index (<25, 25-29.9, and ≥30 kg/m2), previous miscarriage, parity, and fetal sex, adjusted for total volume at first visualization.

MAIN OUTCOME MEASURE(S)

Average change in total fibroid volume during pregnancy.

RESULT(S)

Overall, 9.6% (266/2,774) of women had a visualized fibroid at any time during pregnancy, including 9% (67/745) of non-Hispanic White women, 14% (106/770) of non-Hispanic Black women, 6% (47/794) of Hispanic women, and 10% (46/465) of Asian or Pacific Islander women. The mean total fibroid volume decreased by 1.0% (95% confidence interval [CI], -1.9%, -0.2%) per week, with a variation in starting total volume. On average, the total volume increased by 2.0% (95% CI, -0.3%, 4.5%) per week among women with small volume; decreased by 0.5% (95% CI, -2.0%, 1.0%) per week among women with medium volume; and decreased by 2.2% (95% CI, -3.4%, -1.0%) per week among women with large volume at first visualization. The volume change also varied by race or ethnicity, parity, age, and miscarriage history. For example, non-Hispanic Black women's total fibroid volume decreased more than those of non-Hispanic White, Hispanic and Asian/Pacific Islander women (-2.6%, 0.1%, 0.5%, and 0.9% average change per week, respectively). The visualized fibroid number declined on an average by 1.2% per week (95% CI, -1.9%, -0.5%) without significant variation by demographic characteristics.

CONCLUSION(S)

The total fibroid volume declined on average throughout pregnancy. However, summarizing across all fibroids disguises substantial heterogeneity by starting total fibroid volume and maternal characteristics. The findings may be a useful reference for clinicians to anticipate how fibroids may change in obstetric patients.

CLINICAL TRIAL REGISTRATION NUMBER

NCT00912132.

Leveraging genomic diversity for discovery in an electronic health record linked biobank: the UCLA ATLAS Community Health Initiative

BACKGROUND

Large medical centers in urban areas, like Los Angeles, care for a diverse patient population and offer the potential to study the interplay between genetic ancestry and social determinants of health. Here, we explore the implications of genetic ancestry within the University of California, Los Angeles (UCLA) ATLAS Community Health Initiative-an ancestrally diverse biobank of genomic data linked with de-identified electronic health records (EHRs) of UCLA Health patients (N=36,736).

METHODS

We quantify the extensive continental and subcontinental genetic diversity within the ATLAS data through principal component analysis, identity-by-descent, and genetic admixture. We assess the relationship between genetically inferred ancestry (GIA) and >1500 EHR-derived phenotypes (phecodes). Finally, we demonstrate the utility of genetic data linked with EHR to perform ancestry-specific and multi-ancestry genome and phenome-wide scans across a broad set of disease phenotypes.

RESULTS

We identify 5 continental-scale GIA clusters including European American (EA), African American (AA), Hispanic Latino American (HL), South Asian American (SAA) and East Asian American (EAA) individuals and 7 subcontinental GIA clusters within the EAA GIA corresponding to Chinese American, Vietnamese American, and Japanese American individuals. Although we broadly find that self-identified race/ethnicity (SIRE) is highly correlated with GIA, we still observe marked differences between the two, emphasizing that the populations defined by these two criteria are not analogous. We find a total of 259 significant associations between continental GIA and phecodes even after accounting for individuals' SIRE, demonstrating that for some phenotypes, GIA provides information not already captured by SIRE. GWAS identifies significant associations for liver disease in the 22q13.31 locus across the HL and EAA GIA groups (HL p-value=2.32×10-16, EAA p-value=6.73×10-11). A subsequent PheWAS at the top SNP reveals significant associations with neurologic and neoplastic phenotypes specifically within the HL GIA group.

CONCLUSIONS

Overall, our results explore the interplay between SIRE and GIA within a disease context and underscore the utility of studying the genomes of diverse individuals through biobank-scale genotyping linked with EHR-based phenotyping.

Risk of uterine leiomyoma based on BET1L rs2280543 single nucleotide polymorphism and vegetarian diet

Background

Bet1 Golgi vesicular membrane trafficking protein-like (BET1L) rs2280543 single nucleotide polymorphism (SNP) and diet have been independently associated with uterine leiomyoma (UL). However, whether the SNP and diet could jointly influence the risk of UL is yet to be assessed. Therefore, we investigated the independent and interactive effects of vegetarian diet and BET1L rs2280543 on uterine fibroids in Taiwanese women.

Methods

We linked participants’ electronic data in the Taiwan Biobank (TWB) database to their medical records in the National Health Insurance Research Database (NHIRD). The TWB had genotypic, lifestyle, and biochemical data between 2008 and 2015 and the NHIRD had data on disease diagnoses between 1998 and 2015. In this study, we included 1997 premenopausal women with complete data.

Results

Compared  to participants with the BET1L rs2280543 CC genotype (wildtype), those with CT/CC genotype had an odds ratio (OR) of 0.69 and a 95% confidence interval (CI) of 0.51–0.93. Vegetarian diet and UL were not significantly associated: OR = 1.09 and 95% CI = 0.77–1.55. However, the test for interaction between rs2280543 and vegetarian diet was significant (p = 0.046). Compared to individuals with the CC genotype, the risk of UL was lower among vegetarians with the CT/TT genotype: OR (95% CI) = 0.15 (0.05–0.47).

Conclusion

The BET1L rs2280543 CT/TT genotype was associated with a lower risk of UL especially among vegetarians.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12905-022-01721-1.

Epigenomic and enhancer dysregulation in uterine leiomyomas

BACKGROUND

Uterine leiomyomas, also known as uterine fibroids or myomas, are the most common benign gynecological tumors and are found in women of reproductive and postmenopausal age. There is an exceptionally high prevalence of this tumor in women by the age of 50 years. Black women are particularly affected, with an increased incidence, earlier age of onset, larger and faster growing fibroids and greater severity of symptoms as compared to White women. Although advances in identifying genetic and environmental factors to delineate these fibroids have already been made, only recently has the role of epigenomics in the pathogenesis of this disease been considered.

OBJECTIVE AND RATIONALE

Over recent years, studies have identified multiple epigenomic aberrations that may contribute to leiomyoma development and growth. This review will focus on the most recent discoveries in three categories of epigenomic changes found in uterine fibroids, namely aberrant DNA methylation, histone tail modifications and histone variant exchange, and their translation into altered target gene architecture and transcriptional outcome. The findings demonstrating how the altered 3D shape of the enhancer can regulate gene expression from millions of base pairs away will be discussed. Additionally, translational implications of these discoveries and potential roadblocks in leiomyoma treatment will be addressed.

SEARCH METHODS

A comprehensive PubMed search was performed to identify published articles containing keywords relevant to the focus of the review, such as: uterine leiomyoma, uterine fibroids, epigenetic alterations, epigenomics, stem cells, chromatin modifications, extracellular matrix [ECM] organization, DNA methylation, enhancer, histone post-translational modifications and dysregulated gene expression. Articles until September 2021 were explored and evaluated to identify relevant updates in the field. Most of the articles focused on in the discussion were published between 2015 and 2021, although some key discoveries made before 2015 were included for background information and foundational purposes. We apologize to the authors whose work was not included because of space restrictions or inadvertent omission.

OUTCOMES

Chemical alterations to the DNA structure and of nucleosomal histones, without changing the underlying DNA sequence, have now been implicated in the phenotypic manifestation of uterine leiomyomas. Genome-wide DNA methylation analysis has revealed subsets of either suppressed or overexpressed genes accompanied by aberrant promoter methylation. Furthermore, differential promoter access resulting from altered 3D chromatin structure and histone modifications plays a role in regulating transcription of key genes thought to be involved in leiomyoma etiology. The dysregulated genes function in tumor suppression, apoptosis, angiogenesis, ECM formation, a variety of cancer-related signaling pathways and stem cell differentiation. Aberrant DNA methylation or histone modification is also observed in altering enhancer architecture, which leads to changes in enhancer-promoter contact strength, producing novel explanations for the overexpression of high mobility group AT-hook 2 and gene dysregulation found in mediator complex subunit 12 mutant fibroids. While many molecular mechanisms and epigenomic features have been investigated, the basis for the racial disparity observed among those in the Black population remains unclear.

WIDER IMPLICATIONS

A comprehensive understanding of the exact pathogenesis of uterine leiomyoma is lacking and requires attention as it can provide clues for prevention and viable non-surgical treatment. These findings will widen our knowledge of the role epigenomics plays in the mechanisms related to uterine leiomyoma development and highlight novel approaches for the prevention and identification of epigenome targets for long-term non-invasive treatment options of this significantly common disease.

Research on myoma in Northeastern Romania and socio-medical outcomes

Myomas are the most common benign uterine tumors in women of childbearing age, with an incidence of up to 77% and a major impact on women's health. The aim of our study was to provide information concerning the incidence and prevalence of myomas in the patients admitted to a tertiary referral center in Northeastern Romania. This retrospective study conducted at the Iasi ‘Cuza Voda’ University Hospital of Obstetrics and Gynecology (Romania) included 11,538 patients, representing all patients admitted to the gynecology department between January 2013 and December 2019. During the study interval, the number of hysterectomies (total and for myomas) had increased. The rate of laparoscopic surgery showed a small decrease (31.3% from 34%), classic therapy showed a decrease by more than 10% and the hysteroscopy rate was tripled. There are few studies in the literature that have established with accuracy the incidence of myomas. In the present study, the prevalence of hysterectomy for myomas was 54.42%. Our results are in agreement with the data in the literature, namely that 40-60% of all performed hysterectomies are for myomas. The vast majority of admissions for myomas involve a surgical procedure most commonly hysterectomy.

Molecular and Cellular Insights into the Development of Uterine Fibroids

Uterine leiomyomas represent the most common benign gynecologic tumor. These hormone-dependent smooth-muscle formations occur with an estimated prevalence of ~70% among women of reproductive age and cause symptoms including pain, abnormal uterine bleeding, infertility, and recurrent abortion. Despite the prevalence and public health impact of uterine leiomyomas, available treatments remain limited. Among the potential causes of leiomyomas, early hormonal exposure during periods of development may result in developmental reprogramming via epigenetic changes that persist in adulthood, leading to disease onset or progression. Recent developments in unbiased high-throughput sequencing technology enable powerful approaches to detect driver mutations, yielding new insights into the genomic instability of leiomyomas. Current data also suggest that each leiomyoma originates from the clonal expansion of a single transformed somatic stem cell of the myometrium. In this review, we propose an integrated cellular and molecular view of the origins of leiomyomas, as well as paradigm-shifting studies that will lead to better understanding and the future development of non-surgical treatments for these highly frequent tumors.

Evidence that geographic variation in genetic ancestry associates with uterine fibroids

Uterine fibroids disproportionately impact Black women. Evidence suggests Black women have earlier onset and higher cumulative risk. This risk disparity may be due an imbalance of risk alleles in one parental geographic ancestry subgroup relative to others. We investigated ancestry proportions for the 1000 Genomes phase 3 populations clustered into 6 geographic groups for association with fibroid traits in Black women (n=583 cases, 797 controls) and White women (n=1,195 cases, 1,164 controls). Global ancestry proportions were estimated using ADMIXTURE. Dichotomous (fibroids status and multiple fibroid status) and continuous outcomes (volume and largest dimension) were modeled for association with ancestry proportions using logistic and linear regression adjusting for age. Effect estimates are reported per 10% increase in genetically inferred ancestry proportion. Among AAs, West African (WAFR) ancestry was associated with fibroid risk, East African ancestry was associated with risk of multiple fibroids, Northern European (NEUR) ancestry was protective for multiple fibroids, Southern European ancestry was protective for fibroids and multiple fibroids, and South Asian (SAS) ancestry was positively associated with volume and largest dimension. In EAs, NEUR ancestry was protective for fibroids, SAS ancestry was associated with fibroid risk, and WAFR ancestry was positively associated with volume and largest dimension. These results suggest that a proportion of fibroid risk and fibroid trait racial disparities are due to genetic differences between geographic groups. Further investigation at the local ancestry and single variant levels may yield novel insights about disease architecture and genetic mechanisms underlying ethnic disparities in fibroid risk.

Candidate Genes for Age at Menarche Are Associated With Uterine Leiomyoma

Age at menarche (AAM) is an important marker of the pubertal development and function of the hypothalamic-pituitary-ovarian system. It was reported as a possible factor for a risk of uterine leiomyoma (UL). However, while more than 350 loci for AAM have been determined by genome-wide association studies (GWASs) to date, no studies of these loci for their association with UL have been conducted so far. In this study, we analyzed 52 candidate loci for AAM for possible association with UL in a sample of 569 patients and 981 controls. The results of the study suggested that 23 out of the 52 studied polymorphisms had association with UL. Locus rs7759938 LIN28B was individually associated with the disease according to the dominant model. Twenty loci were associated with UL within 11 most significant models of intergenic interactions. Nine loci involved in 16 most significant models of interactions between single-nucleotide polymorphism (SNP), induced abortions, and chronic endometritis were associated with UL. Among the 23 loci associated with UL, 16 manifested association also with either AAM (7 SNPs) or height and/or body mass index (BMI) (13 SNPs). The above 23 SNPs and 514 SNPs linked to them have non-synonymous, regulatory, and expression quantitative trait locus (eQTL) significance for 35 genes, which play roles in the pathways related to development of the female reproductive organs and hormone-mediated signaling [false discovery rate (FDR) ≤ 0.05]. This is the first study reporting associations of candidate genes for AAM with UL.

Genetic Variation and Hot Flashes: A Systematic Review

CONTEXT

Approximately 70% of women report experiencing vasomotor symptoms (VMS, hot flashes and/or night sweats). The etiology of VMS is not clearly understood but may include genetic factors.

EVIDENCE ACQUISITION

We searched PubMed and Embase in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidance. We included studies on associations between genetic variation and VMS. We excluded studies focused on medication interventions or prevention or treatment of breast cancer.

EVIDENCE SYNTHESIS

Of 202 unique citations, 18 citations met the inclusion criteria. Study sample sizes ranged from 51 to 17 695. Eleven of the 18 studies had fewer than 500 participants; 2 studies had 1000 or more. Overall, statistically significant associations with VMS were found for variants in 14 of the 26 genes assessed in candidate gene studies. The cytochrome P450 family 1 subfamily A member 1 (CYP1B1) gene was the focus of the largest number (n = 7) of studies, but strength and statistical significance of associations of CYP1B1 variants with VMS were inconsistent. A genome-wide association study reported statistically significant associations between 14 single-nucleotide variants in the tachykinin receptor 3 gene and VMS. Heterogeneity across trials regarding VMS measurement methods and effect measures precluded quantitative meta-analysis; there were few studies of each specific genetic variant.

CONCLUSIONS

Genetic variants are associated with VMS. The associations are not limited to variations in sex-steroid metabolism genes. However, studies were few and future studies are needed to confirm and extend these findings.

Role of DNA damage and repair mechanisms in uterine fibroid/leiomyomas: a review

There has been a significant annual increase in the number of cases of uterine leiomyomas or fibroids (UF) among women of all races and ages across the world. A fortune is usually spent by the healthcare sector for fibroid-related treatments and management. Molecular studies have established the higher mutational heterogeneity in UF as compared to normal myometrial cells. The contribution of DNA damage and defects in repair responses further increases the mutational burden on the cells. This in turn leads to genetic instability, associated with cancer risk and other adverse reproductive health outcomes. Such and many more growing bodies of literature have highlighted the genetic/molecular, biochemical and clinical aspects of UF; none the less there appear to be a lacuna bridging the bench to bed gap in addressing and preventing this disease. Presented here is an exhaustive review of not only the molecular mechanisms underlying the predisposition to the disease but also possible strategies to effectively diagnose, prevent, manage, and treat this disease.

Transcriptome Analysis of mRNA in Uterine Leiomyoma Using Next-generation RNA Sequencing

Background:

Uterine leiomyoma is a benign smooth muscle tumor of monoclonal nature in the female reproductive tract and is one of the major health problems. More than 70% of the female population suffers from uterine leiomyoma in their lifetime and in the advanced condition, it is associated with pregnancy complications and infertility.

Objective:

Characterization and relative expression of mRNA transcripts through transcriptome profiling in uterine leiomyoma and adjacent normal myometrium.

Methods:

Uterine leiomyoma tissue of an Indian female, age 32 years, with a family history of leiomyoma (evident from mother’s hysterectomy for the same pathology) was used. Patient showed 9 multiple large lesions appearing heterogeneously, deforming the uterine contour and causing distortion and splaying of the endometrial cavity showing disease aggressiveness was taken for Next-generation sequencing (NGS) to develop whole transcriptome profile along with the adjacent normal myometrium as control. The validation of the relative expression of the selective transcripts was done using Real-Time PCR.

Results:

The transcriptome profile indicated 128 genes up-regulated and 98 down-regulated, with the Log2 fold change ≥ 2 and P ≤ 0.05, highlighting the molecular network closely associated with focal adhesion, hyaluronan and MAPK-signaling pathways. The mean relative fold change obtained from quantitative PCR as well as the P-values of 10 selected transcripts evaluated from student’s t-test were as follows: BCAN: 7.93 fold (p-value =0.0013); AAK1: 2.2 fold (p-value =0.0036); PCBP3: 3.4 fold (p-value =0.0197); MOV10L1: 3.4 fold (p-value =0.0062); TWISTNB: 1.8 fold (p-value =0.006); TMSB15A: 2.1 fold (p-value =0.0023); SMAD1: 0.8 fold (p-value =0.0112); ANXA1: 0.6 fold (p-value =0.0012); FOS: 0.6 fold (p-value =0.0191); SLFN11: 0.56 fold (p-value =0.0001).

Conclusion:

The present study provides a roadmap, towards the analysis of genes and their roles in corresponding pathways throwing light on their possible involvement in the pathology of the disease.

GTn Repeat Microsatellite Instability in Uterine Fibroids

Background:Type I collagen is a triple helix structure with two α1 and one α2 chains. Coordinated biosynthesis of α1 and α2 subunits is very important for tissue morphogenesis, growth, and repair. In contrast, abnormal deposition in response to proinflammatory cytokines is associated with organ dysfunction. In humans, COL1A2 contains two microsatellite loci: one located at the 5’-flanking region is composed of poly CA and poly CG; the other located in the 1st intron is constituted of poly GT. Expression of COL1A2 has been noted in gastric cancer and was positively correlated with degree of invasion and metastases. But no genetic study taking into account polymorphism of COL1A2 in uterine fibroids has been undertaken.

Methods: In this study, repeated dinucleotide GT_n of intron 1 COL1A2 was highlighted in 55 patients with uterine fibroids (UF). Clinical and pathological data were obtained from patient’s records, and other parameters were recorded. Mutation Surveyor version 5.0.1, DnaSP version 5.10, MEGA version 7.0.26, and Arlequin version 3.5.1.3 were used to determine genetics parameters. To estimate genetic variation according to epidemiological parameters, index of genetic differentiation (Fst) and genetic structure (AMOVA) were determined with Arlequin version.

Results: Based on reference microsatellite pattern (GT)₁₄CT(GT)₃CT(GT)₃, 15 haplotypes were found. Among the 15 haplotypes, 12 have mutation at position 2284C > G and 7 at position 2292C > G. Insertions of repeated dinucleotide GT_n were found on three haplotypes against eight haplotypes in which they are deletions. Intron 1 of COL1A2 gene exhibits high genetic diversity in uterine fibroids with 35.34% polymorphic sites, 95.74% of which were parsimoniously variable and an average number of nucleotide difference of 10.442, which reflects an important genetic variability. According to epidemiological parameters, our results showed, for the first time, a genetic structuring of uterine fibroids according to ethnicity, marital status, use of contraception, diet, and physical activity, beyond confirming the involvement dinucleotide length polymorphism GT_n in occurrence of uterine fibroids in Senegalese women.

Conclusion: Results obtained open up avenues for understanding the mechanisms involved in the racial variation in the prevalence of uterine fibroids as well as the predisposing factors.

Genetic predisposition to uterine leiomyoma is determined by loci for genitourinary development and genome stability

Uterine leiomyomas (ULs) are benign tumors that are a major burden to women’s health. A genome-wide association study on 15,453 UL cases and 392,628 controls was performed, followed by replication of the genomic risk in six cohorts. Effects of the risk alleles were evaluated in view of molecular and clinical characteristics. 22 loci displayed a genome-wide significant association. The likely predisposition genes could be grouped to two biological processes. Genes involved in genome stability were represented by TERT, TERC, OBFC1 - highlighting the role of telomere maintenance - TP53 and ATM. Genes involved in genitourinary development, WNT4, WT1, SALL1, MED12, ESR1, GREB1, FOXO1, DMRT1 and uterine stem cell marker antigen CD44, formed another strong subgroup. The combined risk contributed by the 22 loci was associated with MED12 mutation-positive tumors. The findings link genes for uterine development and genetic stability to leiomyomagenesis, and in part explain the more frequent occurrence of UL in women of African origin.

Fibroids – also known as uterine leiomyomas, or myomas – are a very common form of benign tumor that grows in the muscle wall of the uterus. As many as 70% of women develop fibroids in their lifetime. About a fifth of women report symptoms including severe pain, heavy bleeding during periods and complications in pregnancy. In the United States, the cost of treating fibroids is estimated to be $34 billion each year.

Despite the prevalence of fibroids in women, there are few treatments available. Drugs to target them have limited effect and often an invasive procedure such as surgery is needed to remove the tumors. However, a better understanding of the genetics of fibroids could lead to a way to develop better treatment options.

Välimäki, Kuisma et al. used a genome-wide association study to seek out DNA variations that are more common in people with fibroids. Using data from the UK Biobank, the genomes of over 15,000 women with fibroids were analyzed against a control population of over 392,000 individuals. The analysis revealed 22 regions of the genome that were associated with fibroids. These regions included genes that may well contribute to fibroid development, such as the gene TP53, which influences the stability of the genome, and ESR1, which codes for a receptor for estrogen – a hormone known to play a role in the growth of fibroids. Variation in a set of genes known to control development of the female reproductive organs was also identified in women with fibroids.

The findings are the result of the largest genome-wide association study on fibroids, revealing a set of genes that could influence the development of fibroids. Studying these genes could lead to more effective drug development to treat fibroids. Revealing this group of genes could also help to identify women at high risk of developing fibroids and help to prevent or manage the condition.

Clinical, pathologic, cytogenetic, and molecular profiling in self-identified black women with uterine leiomyomata

Black women are disproportionately affected by uterine leiomyomata (UL), or fibroids, compared to other racial groups, having a greater lifetime risk of developing UL and an earlier age of diagnosis. In order to elucidate molecular and genetic mechanisms responsible for the increased prevalence and morbidity associated with UL in black women, clinical, pathologic, cytogenetic, and select molecular profiling (MED12 mutation analysis) of 75 self-reported black women undergoing surgical treatment for UL was performed. Our observations are broadly representative of previous cytogenetic studies of UL: karyotypically abnormal tumors were detected in 30.7% of women and 17.4% of analyzed tumors. No notable association was observed between race and increased occurrence of cytogenetic abnormalities that might contribute to any population-specific morbidity or prevalence rate. Our data on MED12 mutation analyses (73.2% of tumors harbored a MED12 mutation) provide additional support for a significant role of MED12 in tumorigenesis. Although the effect of MED12-mediated tumorigenesis appears significant irrespective of race, other genetic events such as the distribution of karyotypic abnormalities appear differently in black women. This case series indicates that presently recognized genetic and molecular characteristics of UL do not appear to explain the increased prevalence and morbidity of UL in black women.

Admixture mapping of uterine fibroid size and number in African American women

OBJECTIVE

To evaluate the relationship between genetic ancestry and uterine fibroid characteristics.

DESIGN

Cross-sectional study.

SETTING

Not applicable.

PATIENT(S)

A total of 609 African American participants with image- or surgery-confirmed fibroids in a biorepository at Vanderbilt University electronic health record biorepository and the Coronary Artery Risk Development in Young Adults studies were included.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Outcome measures include fibroid number (single vs. multiple), volume of largest fibroid, and largest fibroid dimension of all fibroid measurements.

RESULT(S)

Global ancestry meta-analyses revealed a significant inverse association between percentage of European ancestry and risk of multiple fibroids (odds ratio: 0.78; 95% confidence interval 0.66, 0.93; P=6.05 × 10-3). Local ancestry meta-analyses revealed five suggestive (P<4.80 × 10-3) admixture mapping peaks in 2q14.3-2q21.1, 3p14.2-3p14.1, 7q32.2-7q33, 10q21.1, 14q24.2-14q24.3, for number of fibroids and one suggestive admixture mapping peak (P<1.97 × 10-3) in 10q24.1-10q24.32 for volume of largest fibroid. Single variant association meta-analyses of the strongest associated region from admixture mapping of fibroid number (10q21.1) revealed a strong association at single nucleotide polymorphism variant rs12219990 (odds ratio: 0.41; 95% confidence interval 0.28, 0.60; P=3.82 × 10-6) that was significant after correction for multiple testing.

CONCLUSION(S)

Increasing African ancestry is associated with multiple fibroids but not with fibroid size. Local ancestry analyses identified several novel genomic regions not previously associated with fibroid number and increasing volume. Future studies are needed to explore the genetic impact that ancestry plays into the development of fibroid characteristics.

Uterine Fibroids: Burden and Unmet Medical Need

Uterine fibroids affect a wide cross-section of the population, with prevalence, symptom severity, and overall disease burden generally higher among black women, likely due to both genetic and environmental factors. Potential symptoms of uterine fibroids include painful and excessive uterine bleeding, interference with everyday life and self-image, and impaired fertility. Because of the high estimated prevalence and costs associated with treatments, the direct and indirect costs of uterine fibroids are substantial for both the health care system and the individual patient. Special patient populations—such as black women, women seeking to retain fertility, and women with asymptomatic fibroids—have particular treatment needs that require a variety of diagnostic methods and treatment options. Despite the widespread occurrence of uterine fibroids and newer treatment options, little high-quality data are available to formulate evidence-based guidelines that address these unmet patient needs. Specific areas in need of attention include improving diagnostic techniques, increasing patient access to early treatment, and identifying best practices for this diverse patient population.

A multi-stage genome-wide association study of uterine fibroids in African Americans

Uterine fibroids are benign tumors of the uterus affecting up to 77% of women by menopause. They are the leading indication for hysterectomy, and account for $34 billion annually in the United States. Race/ethnicity and age are the strongest known risk factors. African American (AA) women have higher prevalence, earlier onset, and larger and more numerous fibroids than European American women. We conducted a multi-stage genome-wide association study (GWAS) of fibroid risk among AA women followed by in silico genetically predicted gene expression profiling of top hits. In Stage 1, cases and controls were confirmed by pelvic imaging, genotyped and imputed to 1000 Genomes. Stage 2 used self-reported fibroid and GWAS data from 23andMe, Inc. and the Black Women's Health Study. Associations with fibroid risk were modeled using logistic regression adjusted for principal components, followed by meta-analysis of results. We observed a significant association among 3399 AA cases and 4764 AA controls at rs739187 (risk-allele frequency = 0.27) in CYTH4 (OR (95% confidence interval) = 1.23 (1.16-1.30), p value = 7.82 × 10-9). Evaluation of the genetic association results with MetaXcan identified lower predicted gene expression of CYTH4 in thyroid tissue as significantly associated with fibroid risk (p value = 5.86 × 10-8). In this first multi-stage GWAS for fibroids among AA women, we identified a novel risk locus for fibroids within CYTH4 that impacts gene expression in thyroid and has potential biological relevance for fibroids.

Human Chorionic Gonadotrophin as a Possible Mediator of Leiomyoma Growth during Pregnancy: Molecular Mechanisms

Uterine fibroids are the most common gynecologic benign tumors. Studies supporting a strong pregnancy-related growth of leiomyomas generally claimed a crucial role of sex steroid hormones. However, sex steroids are unlikely the unique actors involved as estrogen and progesterone achieve a pick serum concentration in the last trimester while leiomyomas show a typical increase during the first trimester. Given the rapid exponential raise in serum human Chorionic Gonadotrophin (hCG) at the beginning of gestation, we conducted a review to assess the potential role of hCG in the striking growth of leiomyomas during initial pregnancy. Fibroid growth during initial pregnancy seems to correlate to the similar increase of serum hCG levels until 12 weeks of gestation. The presence of functional Luteinizing Hormone/human Chorionic Gonadotropin (LH/hCG) receptors was demonstrated on leiomyomas. In vitro treatment of leiomyoma cells with hCG determines an up to 500% increase in cell number after three days. Expression of cyclin E and cyclin-dependent kinase 1 was significantly increased in leiomyoma cells by hCG treatment. Moreover, upon binding to the receptor, hCG stimulates prolactin secretion in leiomyoma cells, promoting cell proliferation via the mitogen-activated protein kinase cascade. Fibroid enlargement during initial pregnancy may be regulated by serum hCG.

Defective expression of ATG4D abrogates autophagy and promotes growth in human uterine fibroids

Uterine fibroids (UF) are the most common pelvic tumors in women of reproductive-age and they usually cause heavy menstrual bleeding, pain and infertility. Autophagy is a collection of processes that enables the cells to digest and recycle their cytoplasmic contents, such as toxic protein aggregates, defunct or disused organelles and invading microorganisms. Dysregulation in autophagy process were described in neoplasms; however, the contribution of autophagy to the pathogenesis of UF remains unknown. In this study, we demonstrate that autophagy is deregulated in human UF as evidenced by significant accumulation of autophagosome in human UF cells compared to normal myometrium cells. Analysis of the autophagy markers revealed an enhanced initiation of the autophagy in UF tissues compared to their adjacent myometrial tissues (MyoF). However, autophagosome maturation and flux was blocked in UF tissues, as marked by accumulation of LC3-B and P62 protein. This block was associated with defective expression of autophagy-related protein 4 (ATG4) in the UF tissues compared to MyoF in ~90% of patient samples. Silencing of ATG4D in normal human myometrial cells resulted in defective autophagy flux, enhanced cell proliferation and increased extracellular matrix production, which phenocopy UF cell line. This study indicates that impairment of autophagy flux secondary to defective expression of ATG4D expression is a new mechanistic aberration that contributes to UF pathogenesis. Targeting autophagy pathway could provide novel medical therapeutic approach for non-surgical treatment of UF.

African genetic ancestry interacts with body mass index to modify risk for uterine fibroids

Race, specifically African ancestry, and obesity are important risk factors for uterine fibroids, and likely interact to provide the right conditions for fibroid growth. However, existing studies largely focus on the main-effects rather than their interaction. Here, we firstly provide evidence for interaction between categories of body mass index (BMI) and reported-race in relation to uterine fibroids. We then investigate whether the association between inferred local European ancestry and fibroid risk is modified by BMI in African American (AA) women in the Vanderbilt University Medical Center bio-repository (BioVU) (539 cases and 794 controls) and the Coronary Artery Risk Development in Young Adults study (CARDIA, 264 cases and 173 controls). We used multiple logistic regression to evaluate interactions between local European ancestry and BMI in relation to fibroid risk, then performed fixed effects meta-analysis. Statistical significance threshold for local-ancestry and BMI interactions was empirically estimated with 10,000 permutations (p-value = 1.18x10-4). Admixture mapping detected an association between European ancestry and fibroid risk which was modified by BMI (continuous-interaction p-value = 3.75x10-5) around ADTRP (chromosome 6p24); the strongest association was found in the obese category (ancestry odds ratio (AOR) = 0.51, p-value = 2.23x10-5). Evaluation of interaction between genotyped/imputed variants and BMI in this targeted region suggested race-specific interaction, present in AAs only; strongest evidence was found for insertion/deletion variant (6:11946435), again in the obese category (OR = 1.66, p-value = 1.72x10-6). We found nominal evidence for interaction between local ancestry and BMI at a previously reported region in chromosome 2q31-32, which includes COL5A2, and TFPI, an immediate downstream target of ADTRP. Interactions between BMI and SNPs (single nucleotide polymorphisms) found in this region in AA women were also detected in an independent European American population of 1,195 cases and 1,164 controls. Findings from our study provide an example of how modifiable and non-modifiable factors may interact to influence fibroid risk and suggest a biological role for BMI in fibroid etiology.

Epidemiology of Uterine Fibroids: From Menarche to Menopause

Uterine leiomyomata (UL) have a substantial impact on women's health, but relatively few studies have identified opportunities for primary prevention of these neoplasms. Most established risk factors are not modifiable, including premenopausal age, African ancestry, age at menarche, and childbearing history. The main challenge in studying UL is that a large proportion of tumors are asymptomatic. Herein, we review the epidemiology of UL from published studies to date. We highlight the advantages of ultrasound screening studies and the ways in which their innovative methods have helped clarify the etiology of disease. We conclude with a discussion of promising new hypotheses.

Fibroids: Genotype and Phenotype

Fibroids represent a major public health care problem as the most prevalent pelvic tumors in women of reproductive age and as the leading cause of gynecologic surgeries in the United States. The recent advances in the genomic technologies including genome-wide association studies and high-throughput sequencing provide insight into their pathogenesis and molecular classification. Understanding the molecular basis of fibroids may facilitate development of effective targeted treatment options of this very common disease.

FASN, dietary fat intake, and risk of uterine leiomyomata in the Black Women's Health Study

OBJECTIVE

To replicate results from a previous genome-wide association study of European ancestry women, in which a positive association was found between uterine leiomyomata (UL) and rs4247357, a single-nucleotide polymorphism located near the fatty acid synthase (FASN) gene.

DESIGN

Prospective cohort study.

SETTING

Not applicable.

PATIENT(S)

African-American women aged 23-50 years, who were premenopausal and had an intact uterus in 1997.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

We genotyped rs4247357 among 2,301 incident UL cases and 3,005 controls from the Black Women's Health Study (1997-2011). Odds ratios (ORs) and 95% confidence intervals (CI) were estimated using logistic regression with control for age, geographic region of residence, and percent European ancestry using a panel of validated ancestry informative markers.

RESULT(S)

Overall, rs4247357 was not associated with UL risk. Relative to the CC genotype, ORs were 1.04 (95% CI 0.92-1.19) for the AC genotype and 1.09 (95% CI 0.93-1.29) for the AA genotype. A positive association was found, however, among those with higher European ancestry (≥40%). Relative to the CC genotype, ORs were 2.03 (95% CI 1.12-3.69) for the AC genotype and 2.44 (95% CI 1.20-4.96) for the AA genotype. Dietary fat intake also appeared to modify the FASN-UL association.

CONCLUSION(S)

Although there was little overall association between rs4247357 and UL risk, a positive association was observed among women with ≥40% European ancestry. Direct sequencing of this genomic region might be warranted to determine whether rs4247357, or some other variant, is causally related to UL.

Uterine fibroids

Uterine fibroids (also known as leiomyomas or myomas) are common clonal neoplasms of the uterus. Fibroids have both smooth muscle and fibroblast components, in addition to a substantial amount of fibrous extracellular matrix, which all contribute to the pathogenetic process. Fibroids are extremely heterogeneous in their pathophysiology, size, location and clinical symptomatology. They are also a part of a range of disease in which some variants have facets of malignant behaviour but overall are benign. Risk for fibroids is associated with race; black women have a higher risk of developing fibroids earlier in life than their white counterparts and also develop more-severe forms of the disease. Clinically, fibroids account for one-third to half of all hysterectomies and are associated with substantial morbidity and health care costs for women of reproductive age. Indeed, current treatments are primarily surgical and interventional; approximately three-quarters of all fibroid treatments are hysterectomies. However, clinical innovations are emerging in the use of progesterone receptor modulators as a medical therapy. New information is rapidly accumulating about the genetic subgroups that lead to fibroid formation, which might aid further understanding of the clinical heterogeneity of this disease and lead to individualized treatments. This information is a crucial development given the current lack of high-quality evidence on which to base therapeutic decisions.

Epidemiology of Uterine Myomas: A Review

Myomas are the most common benign tumors of the genital organs in women of childbearing age, causing significant morbidity and impairing their quality of life. In our investigation, we have reviewed the epidemiological data related to the development of myomas in order to homogenize the current data. Therefore, a MEDLINE and PubMed search, for the years 1990-2013, was conducted using a combination of keywords, such as "myoma," "leiomyoma," "fibroids," "myomectomy," "lifestyle," "cigarette," "alcohol," "vitamins," "diet," and "hysterectomy". Randomized controlled studies were selected based upon the authors’ estimation. Peer-reviewed articles examining myomas were sorted by their relevance and included in this research. Additional articles were also identified from the references of the retrieved papers and included according to authors’ estimation.

Many epidemiologic factors are linked to the development of myomas; however, many are not yet fully understood. These factors include age, race, heritage, reproductive factors, sex hormones, obesity, lifestyle (diet, caffeine and alcohol consumption, smoking, physical activity and stress), environmental and other influences, such as hypertension and infection. Some of the epidemiological data is conflicting. Thus, more research is needed to understand all the risk factors that contribute to myoma formation and how they exactly influence their onset and growth.

Mapping asthma-associated variants in admixed populations

Admixed populations arise when two or more previously isolated populations interbreed. Mapping asthma susceptibility loci in an admixed population using admixture mapping (AM) involves screening the genome of individuals of mixed ancestry for chromosomal regions that have a higher frequency of alleles from a parental population with higher asthma risk as compared with parental population with lower asthma risk. AM takes advantage of the admixture created in populations of mixed ancestry to identify genomic regions where an association exists between genetic ancestry and asthma (in contrast to between the genotype of the marker and asthma). The theory behind AM is that chromosomal segments of affected individuals contain a significantly higher-than-average proportion of alleles from the high-risk parental population and thus are more likely to harbor disease-associated loci. Criteria to evaluate the applicability of AM as a gene mapping approach include: (1) the prevalence of the disease differences in ancestral populations from which the admixed population was formed; (2) a measurable difference in disease-causing alleles between the parental populations; (3) reduced linkage disequilibrium (LD) between unlinked loci across chromosomes and strong LD between neighboring loci; (4) a set of markers with noticeable allele-frequency differences between parental populations that contributes to the admixed population (single nucleotide polymorphisms (SNPs) are the markers of choice because they are abundant, stable, relatively cheap to genotype, and informative with regard to the LD structure of chromosomal segments); and (5) there is an understanding of the extent of segmental chromosomal admixtures and their interactions with environmental factors. Although genome-wide association studies have contributed greatly to our understanding of the genetic components of asthma, the large and increasing degree of admixture in populations across the world create many challenges for further efforts to map disease-causing genes. This review, summarizes the historical context of admixed populations and AM, and considers current opportunities to use AM to map asthma genes. In addition, we provide an overview of the potential limitations and future directions of AM in biomedical research, including joint admixture and association mapping for asthma and asthma-related disorders.

Genetic determinants of uterine fibroid size in the multiethnic NIEHS uterine fibroid study

We conducted a follow-up association study across extended candidate chromosomal regions for uterine leiomyoma (UL), or fibroids, to search for loci influencing the size of UL in 916 premenopausal North American women participants to the NIEHS uterine fibroid study. Proportional odds models with adjustments for confounders were fitted to evaluate the association of a final set of 2,484 single nucleotide polymorphisms (SNPs) with the size of uterine fibroids measured by transabdominal and transvaginal ultrasounds. SNP association with UL size was tested in a case-only design comparing three categories of tumor size (small, medium and large tumors) and in a design that included UL-free controls as the lowest category of a four-level ordinal outcome to account for misclassifications due to small, undetected tumors. In the case-only design, rs2285789 in SORCS2 (sortilin-related VPS10 domain containing receptor 2) was the sole variant that remained significant after correction for multiple testing (Bonferroni-adjusted P=0.037). Several other SNPs, namely those located in MYT1L, TMCC1 and BRCA1, reached promising associations. In the design that included the controls, several genes of potential relevance to UL pathogenesis were associated (Bonferroni-unadjusted P < 0.01) with tumor size, particularly LIFR-AS1 (leukemia inhibitory factor receptor alpha-antisense RNA 1), which showed the strongest association (Bonferroni-unadjusted P=0.0006) among the genes with regulated expression in UL. In conclusion, SORCS2, a known GWAS candidate for circulating IGF-I and IGFBP-3, may act through IGF-I signaling to affect the size of fibroids. Through down-regulation of LIFR, LIFR-AS1 may mediate the inhibitory action of LIF (leukemia inhibitory factor), a cytokine involved in embryonic uterine development. Replication analyses are needed to substantiate our reported associations of SORCS2 and LIFR-AS1 with the size of fibroids.

Fine mapping of the uterine leiomyoma locus on 1q43 close to a lncRNA in the RGS7-FH interval

Mutations in fumarate hydratase (FH) on chromosome 1q43 cause a rare cancer syndrome, hereditary leiomyomatosis and renal cell cancer (HLRCC), but are rare in nonsyndromic and common uterine leiomyoma (UL) or fibroids. Studies suggested that variants in FH or in a linked gene may also predispose to UL. We re-sequenced 2.3 Mb of DNA spanning FH in 96 UL cases and controls from the multiethnic NIEHS-uterine fibroid study, and in 18 HLRCC-associated UL probands from European families then selected 221 informative SNPs for follow-up genotyping. We report promising susceptibility associations with UL peaking at rs78220092 (P=7.0×10(-5)) in the RGS7-FH interval in African Americans. In race-combined analyses and in meta-analyses (n=916), we identified promising associations with risk peaking upstream of a non-protein coding RNA (lncRNA) locus located in the RGS7-FH interval closer to RGS7, and associations with tumor size peaking in the distal phospholipase D family, member 5 (PLD5) gene at rs2654879 (P=1.7×10(-4)). We corroborated previously reported FH mutations in nine out of the 18 HLRCC-associated UL cases and identified two missense mutations in FH in only two nonsyndromic UL cases and one control. Our fine association mapping and integration of existing gene profiling data showing upregulated expression of the lncRNA and downregulation of PLD5 in fibroids, as compared to matched myometrium, suggest a potential role of this genomic region in UL pathogenesis. While the identified variations at 1q43 represent a potential risk locus for UL, future replication analyses are required to substantiate our observation.

Evaluation of GWAS candidate susceptibility loci for uterine leiomyoma in the multi-ethnic NIEHS uterine fibroid study

We evaluated the association of 56 candidate SNPs identified in two published genome-wide association studies (GWAS) of uterine leiomyoma (UL), or fibroids, with the risk and tumor size in the multi-ethnic uterine fibroid study (NIEHS-UFS). The selected SNPs were genotyped in 916 premenopausal women of African American (AA) and European American (EA) descents and their association with the outcomes was evaluated in race-stratified models and in meta-analysis of risk in NIEHS-UFS and discovery and replication GWAS in the Japanese population. We report moderate associations of variant rs4954368 in THSD7B (thrombospondin, type I, domain containing 7B) with tumor size in pooled analysis of AA and EA samples (P = 0.004), and at TNRC6B (trinucleotide repeat containing 6B) variants rs138039 and rs139909 in EA (P = 0.001 and 0.008, respectively). The most significant associations with risk in meta-analysis were observed at TNRC6B variants rs739182 (P = 3.7 × 10(-10)) and rs2072858 (P = 1.1 × 10(-9)) and were stronger than those reported in the discovery GWAS (P = 2.01 × 10(-8) and 2.58 × 10(-8), respectively). The present study failed to replicate the associations reported for CCDC57 and FASN in a discovery GWAS in populations of European descent. Consistent with previous replication studies in the Right From the Start Study (RFTS) and the BioVU DNA repository, we provide independent evidence for association of TNRC6B with both risk and size of UL. The present study is the first to report a replicated association of THSD7B with UL, albeit with tumor size and not with risk.

Epidemiological and genetic clues for molecular mechanisms involved in uterine leiomyoma development and growth

BACKGROUND

Uterine leiomyomas (fibroids) are highly prevalent benign smooth muscle tumors of the uterus. In the USA, the lifetime risk for women developing uterine leiomyomas is estimated as up to 75%. Except for hysterectomy, most therapies or treatments often provide only partial or temporary relief and are not successful in every patient. There is a clear racial disparity in the disease; African-American women are estimated to be three times more likely to develop uterine leiomyomas and generally develop more severe symptoms. There is also familial clustering between first-degree relatives and twins, and multiple inherited syndromes in which fibroid development occurs. Leiomyomas have been described as clonal and hormonally regulated, but despite the healthcare burden imposed by the disease, the etiology of uterine leiomyomas remains largely unknown. The mechanisms involved in their growth are also essentially unknown, which has contributed to the slow progress in development of effective treatment options.

METHODS

A comprehensive PubMed search for and critical assessment of articles related to the epidemiological, biological and genetic clues for uterine leiomyoma development was performed. The individual functions of some of the best candidate genes are explained to provide more insight into their biological function and to interconnect and organize genes and pathways in one overarching figure that represents the current state of knowledge about uterine leiomyoma development and growth.

RESULTS

In this review, the widely recognized roles of estrogen and progesterone in uterine leiomyoma pathobiology on the basis of clinical and experimental data are presented. This is followed by fundamental aspects and concepts including the possible cellular origin of uterine fibroids. The central themes in the subsequent parts are cytogenetic aberrations in leiomyomas and the racial/ethnic disparities in uterine fibroid biology. Then, the attributes of various in vitro and in vivo, human syndrome, rodent xenograft, naturally mutant, and genetically modified models used to study possible molecular mechanisms of leiomyoma development and growth are described. Particular emphasis is placed on known links to fibrosis, hypertrophy, and hyperplasia and genes that are potentially important in these processes.

CONCLUSIONS

Menstrual cycle-related injury and repair and coinciding hormonal cycling appears to affect myometrial stem cells that, at a certain stage of fibroid development, often obtain cytogenetic aberrations and mutations of Mediator complex subunit 12 (MED12). Mammalian target of rapamycin (mTOR), a master regulator of proliferation, is activated in many of these tumors, possibly by mechanisms that are similar to some human fibrosis syndromes and/or by mutation of upstream tumor suppressor genes. Animal models of the disease support some of these dysregulated pathways in fibroid etiology or pathogenesis, but none are definitive. All of this suggests that there are likely several key mechanisms involved in the disease that, in addition to increasing the complexity of uterine fibroid pathobiology, offer possible approaches for patient-specific therapies. A final model that incorporates many of these reported mechanisms is presented with a discussion of their implications for leiomyoma clinical practice.

Admixture mapping of genetic variants for uterine fibroids

Uterine leiomyoma (UL) are benign neoplasms arising from the smooth muscle cells of the uterus. One of the established risk factors for UL is African American ethnicity. Studies have consistently shown that African Americans have 2-3 times higher risk compared with that of non-Hispanic Whites. However, there is still no adequate explanation for the higher risk among African Americans. To investigate the genetic contribution to the observed difference between the African American and European American populations, we conducted an admixture scan in 525 eligible African American women participants to the NIEHS uterine fibroid study (NIEHS-UFS). In models with no stratification, we found multiple genomic regions showing significant and suggestive evidence of association, with chromosomal band 2q32.2 at rs256552 showing the highest score (Z-score = 7.86, Bonferroni adjusted p-value = 5.5×10^-12) consistent with the suggestive evidence reported for this genomic region in the Black Women's Health Study. However, in models stratified by the body mass index (BMI) covariate, chromosomal 1q42.2 was the sole genomic region that consistently showed suggestive associations across the BMI categories tested (Z-scores ≤ -3.96, Bonferroni adjusted p-values ≤ 0.107). In age-stratified models, a significant association was observed in the older category (age > 40) reaching a Z-score of 6.44 (Bonferroni-adjusted p-value = 1.64 × 10^-7) at rs256552. The mean percentage of European ancestry among cases was lower than that among controls in the NIEHS-UFS study. However, our study did not show a significant association between mean percentage of European ancestry and UL.

Depressive symptoms and risk of uterine leiomyomata

OBJECTIVE

Uterine leiomyomata (UL) are a major source of gynecologic morbidity and the primary indication for hysterectomy. Depression can cause dysregulation of the hypothalamic-pituitary-adrenal axis, which may affect the synthesis of reproductive hormones involved in UL pathogenesis. We assessed the association between depressive symptoms and UL among 15,963 premenopausal women.

STUDY DESIGN

Data were derived from the Black Women's Health Study, a prospective cohort study. In 1999 and 2005, the Center for Epidemiologic Studies Depression Scale (CES-D) was used to ascertain depressive symptoms. On biennial follow-up questionnaires from 1999 through 2011, women reported physician-diagnosed depression, antidepressant use, and UL diagnoses. Incidence rate ratios (IRRs) and 95% confidence intervals (CIs) were estimated using multivariable Cox regression.

RESULTS

There were 4722 incident UL cases diagnosed by ultrasound (n=3793) or surgery (n=929) during 131,262 person-years of follow-up. Relative to baseline CES-D scores<16, IRRs were 1.05 (95% CI, 0.98-1.13) for CES-D scores 16-24 and 1.16 (95% CI, 1.06-1.27) for CES-D scores≥25 (P-trend=.001). IRRs for current and past physician-diagnosed depression relative to no depression were 1.15 (95% CI, 0.98-1.34) and 1.25 (95% CI, 1.13-1.39), respectively. Results persisted after further control for antidepressant use. IRRs for current and past use of antidepressants (any indication) relative to never use were 1.11 (95% CI, 0.97-1.28) and 1.32 (95% CI, 1.14-1.52), respectively.

CONCLUSION

In this cohort of black women, greater depressive symptoms were associated with UL, independent of antidepressant use, supporting the hypothesis that dysregulation of the hypothalamic-pituitary-adrenal axis increases UL risk.

Follow-up to genome-wide linkage and admixture mapping studies implicates components of the extracellular matrix in susceptibility to and size of uterine fibroids

OBJECTIVE

To conduct a follow-up association mapping to independent genome-wide linkage and admixture mapping studies of uterine leiomyoma.

DESIGN

Case-control, cross-sectional study.

SETTING

Not applicable.

PATIENT(S)

A total of 1,045 premenopausal North American participants in the National Institute of Environmental Health Sciences Uterine Fibroid Study.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

We genotyped 2,772 single-nucleotide polymorphisms from candidate genes located in peaks of linkage (2q37, 3p21, 5p13, 10p11, 11p15, 12q14, and 17q25) or admixture linkage disequilibrium (2q37, 4p16.1, and 10q26) mapping and reported to have regulated expression in uterine fibroids.

RESULT(S)

We report significant associations of variant members of the collagen gene family with risk and tumor size, including missense variants in COL6A3 and COL13A, with replications in African American and European American study groups. Furthermore, the cell-matrix Rho GTPase-encoding ARHGAP26 gene, and MAN1C1, a gene encoding a Golgi mannosidase involved in the maturation of procollagens, emerged as new candidate uterine leiomyoma genes affecting both risk and tumor size.

CONCLUSION(S)

Our data converge onto a possible model of uterine leiomyoma pathogenesis resulting from altered regulation, maintenance, and/or renewal of the extracellular matrix.

African ancestry influences CCR5 -2459G>A genotype-associated virologic success of highly active antiretroviral therapy

INTRODUCTION

In a North American, HIV-positive, highly active antiretroviral therapy (HAART)-treated, adherent cohort of self-identified white and black patients, we previously observed that chemokine (C-C motif) receptor 5 (CCR5) -2459G>A genotype had a strong association with time to achieve virologic success (TVLS) in black but not in white patients.

METHODS

Using 128 genome-wide ancestry informative markers, we performed a quantitative assessment of ancestry in these patients (n = 310) to determine (1) whether CCR5 -2459G>A genotype is still associated with TVLS of HAART when ancestry, not self-identified race, is considered and (2) whether this association is influenced by varying African ancestry.

RESULTS

We found that the interaction between CCR5 -2459G>A genotype and African ancestry (≤ 0.125 vs. ≥ 0.425 and <0.71 vs. ≥ 0.71) was significantly associated with TVLS (GG compared with AA, P = 0.044 and 0.018, respectively). Furthermore, the association between CCR5 -2459G>A genotype and TVLS was stronger in patients with African ancestry ≥ 0.71 than in patients with African ancestry ≥ 0.452, in both Kaplan-Meier (log-rank P = 0.039 and 0.057, respectively, for AA, GA, and GG) and Cox proportional hazards regression (relative hazard for GG compared with AA 2.59 [95% confidence interval: 1.27 to 5.22; P = 0.01] and 2.26 [95% confidence interval: 1.18 to 4.32; P = 0.01], respectively) analyses.

CONCLUSIONS

We observed that the association between CCR5 -2459G>A genotype and TVLS of HAART increased with stronger African ancestry. Understanding the genomic mechanisms by which African ancestry influences this association is critical and requires further studies.

Distribution of CYP17α polymorphism and selected physiochemical factors of uterine leiomyoma in Barbados

Uterine leiomyoma is a major reproductive health disease among women and in particular Black women. The present study sought to determine whether a single nucleotide polymorphism (SNP) of CYP17 (rs743572) was associated with the risk of developing uterine leiomyoma (UL) in affected women in Barbados; a majority Black population. It also sought to determine if BMI, waist circumference and oestradiol levels were associated with UL in this group. A total of 96 random persons were assessed in a case–control study using a PCR-RFLP assay, and measurements of body mass index, waist circumference, and oestradiol levels were also assessed. Our results showed no genetic association with the risk of UL and this gene. The genetic distribution of CYP 17α- alleles resembled a normal Hardy–Weinberg distribution, and a relatively low risk of 0.25 at a confidence interval at 95%, of UL disease development. However, a significant association was found between oestradiol levels and fibroids, as well as oestradiol levels and BMI, at P < 0.05 among cases. Therefore our study indicates that significant associations between physiochemical factors comprising BMI, waist circumference, and oestrogen levels are disease indicators in this population. In conclusion, our findings suggest that obesity and its associated risk factors are important in a majority Black Caribbean population, although the sample size needs to be increased.

The future for genetic studies in reproduction

Genetic factors contribute to risk of many common diseases affecting reproduction and fertility. In recent years, methods for genome-wide association studies (GWAS) have revolutionized gene discovery for common traits and diseases. Results of GWAS are documented in the Catalog of Published Genome-Wide Association Studies at the National Human Genome Research Institute and report over 70 publications for 32 traits and diseases associated with reproduction. These include endometriosis, uterine fibroids, age at menarche and age at menopause. Results that pass appropriate stringent levels of significance are generally well replicated in independent studies. Examples of genetic variation affecting twinning rate, infertility, endometriosis and age at menarche demonstrate that the spectrum of disease-related variants for reproductive traits is similar to most other common diseases. GWAS 'hits' provide novel insights into biological pathways and the translational value of these studies lies in discovery of novel gene targets for biomarkers, drug development and greater understanding of environmental factors contributing to disease risk. Results also show that genetic data can help define sub-types of disease and co-morbidity with other traits and diseases. To date, many studies on reproductive traits have used relatively small samples. Future genetic marker studies in large samples with detailed phenotypic and clinical information will yield new insights into disease risk, disease classification and co-morbidity for many diseases associated with reproduction and infertility.

Is the observed association between dairy intake and fibroids in African Americans explained by genetic ancestry?

Uterine leiomyomata are a major source of gynecological morbidity and are 2-3 times more prevalent in African Americans than European Americans. In an earlier report, we found that dairy intake was inversely associated with uterine leiomyomata among African Americans. Because African Americans are more likely to have lactose intolerance and avoid dairy products, the observed association might have been confounded by genetic ancestry. This report reevaluates the dairy-uterine leiomyomata association after accounting for genetic ancestry among 1,968 cases and 2,183 noncases from the Black Women's Health Study (1997-2007). Dairy intake was estimated by using food frequency questionnaires in 1995 and 2001. Percent European ancestry was estimated by using a panel of ancestry informative markers. Incidence rate ratios and 95% confidence intervals were estimated by using Cox regression, with adjustment for potential confounders and percent European ancestry. Incidence rate ratios comparing 1, 2, 3, and ≥4 servings/day with <1 serving/day of dairy products were 0.95 (95% confidence interval (CI): 0.85, 1.06), 0.75 (95% CI: 0.61, 0.92), 0.77 (95% CI: 0.57, 1.04), and 0.59 (95% CI: 0.41, 0.86), respectively (Ptrend = 0.0003). These effect estimates were similar to those obtained without control for ancestry. The findings suggest that the observed inverse association between dairy consumption and uterine leiomyomata in African Americans is not explained by percent European ancestry.

Cytokine patterns differ seasonally between women with and without uterine leiomyomata

PROBLEM

Uterine leiomyomata are the most common reproductive tumor in women, and their cause is not known.

METHODS OF STUDY

Plasma samples from 155 women (74 with and 81 without ultrasound-confirmed leiomyoma) from a new study of leiomyoma risk factors in the Detroit, Michigan area, were examined for any cross-sectional associations between commonly examined cytokines and leiomyoma presence.

RESULTS

Associations varied by season of sample collection defined a priori as winter (December-February) and non-winter seasons. In the winter months, interleukin (IL)13 and IL17 were positively and IP10 was inversely associated with having a leiomyoma. In the non-winter samples, VEGF, G-CSF, and IP10 were positively associated and Monocyte chemotactic protein-1, IL13, and IL17 were inversely associated with having a leiomyoma. Associations were not changed by adjustment for age or BMI.

CONCLUSIONS

These data suggest that new insight into leiomyoma formation may be acquired through investigation of the immune system.