Pathways to hysterectomy: insights from longitudinal twin research

Genome-wide association and epidemiological analyses reveal common genetic origins between uterine leiomyomata and endometriosis

Uterine leiomyomata (UL) are the most common neoplasms of the female reproductive tract and primary cause for hysterectomy, leading to considerable morbidity and high economic burden. Here we conduct a GWAS meta-analysis in 35,474 cases and 267,505 female controls of European ancestry, identifying eight novel genome-wide significant (P < 5 × 10^-8) loci, in addition to confirming 21 previously reported loci, including multiple independent signals at 10 loci. Phenotypic stratification of UL by heavy menstrual bleeding in 3409 cases and 199,171 female controls reveals genome-wide significant associations at three of the 29 UL loci: 5p15.33 (TERT), 5q35.2 (FGFR4) and 11q22.3 (ATM). Four loci identified in the meta-analysis are also associated with endometriosis risk; an epidemiological meta-analysis across 402,868 women suggests at least a doubling of risk for UL diagnosis among those with a history of endometriosis. These findings increase our understanding of genetic contribution and biology underlying UL development, and suggest overlapping genetic origins with endometriosis.

Burden of Uterine Fibroids: An African Perspective, A Call for Action and Opportunity for Intervention

Black women carry the burden of uterine fibroids, (AKA uterine leiomyomas), at a much higher rate than their racial counterparts. Thus, increasing awareness and discovering a solution to an endemic problem that plagues Sub-Saharan Africa is of critical importance, not only for the region itself, but also for the medical community globally. A collaborative, patient oriented, cost effective, and culturally sensitive approach must be at the forefront of this endeavor. While the exact pathogenesis of uterine fibroid development remains elusive, the racial disparity is well documented. Moreover, in the developed world, women are able to seek treatment through surgical and non-surgical means; however, sub-Saharan regions face their own challenges that, if not addressed, can ultimately extinguish the lives of many suffering women. Unfortunately, the literature is scarce on how to prevent fibroid development, which may be critical for women who do not have access to effective interventions. Recent research from our group and others has shown that vitamin D deficiency plays an important role in fibroid development and may be a preventable risk factor. Daily vitamin D supplementation is a low cost, effective intervention that could be implemented throughout the Sub-Saharan region. Similarly, education and increased awareness as to the nature and symptoms of uterine fibroids could improve the quality of life, remove negative social stigma, and reduce morbidity and mortality rates in women who seek medical care with advanced uterine fibroids.

Complex genetics of female fertility

Variation in reproductive lifespan and female fertility have implications for health, population size and ageing. Fertility declines well before general signs of menopause and is also adversely affected by common reproductive diseases, including polycystic ovarian syndrome (PCOS) and endometriosis. Understanding the factors that regulate the timing of puberty and menopause, and the relationships with fertility are important for individuals and for policy. Substantial genetic variation exists for common traits associated with reproductive lifespan and for common diseases influencing female fertility. Genetic studies have identified mutations in genes contributing to disorders of reproduction, and in the last ten years, genome-wide association studies (GWAS) have transformed our understanding of common genetic contributions to these complex traits and diseases. These studies have made great progress towards understanding the genetic factors contributing to variation in traits and diseases influencing female fertility. The data emerging from GWAS demonstrate the utility of genetics to explain epidemiological observations, revealing shared biological pathways linking puberty timing, fertility, reproductive ageing and health outcomes. Many variants implicate DNA damage/repair genes in variation in the age at menopause with implications for follicle health and ageing. In addition to the discovery of individual genes and pathways, the increasingly powerful studies on common genetic risk factors help interpret the underlying relationships and direction of causation in the regulation of reproductive lifespan, fertility and related traits.

Association of BET1L and TNRC6B with uterine leiomyoma risk and its relevant clinical features in Han Chinese population

Previous studies have shown that uterine leiomyomas (UL) are benign tumours with contributions from environmental and genetic factors. We aimed to replicate two initial significant genetic factors, TNRC6B and BET1L, in a Han Chinese population. A total of 2,055 study subjects were recruited, and 55 SNPs mapped to TNRC6B and BET1L were selected and genotyped in samples from these subjects. Genetic associations were analysed at both the single marker and haplotype levels. Associations between targeted SNPs and relevant clinical features of UL were analysed in case only samples. Functional consequences of significant SNPs were analysed by bioinformatics tools. Two SNPs, rs2280543 from BET1L (χ² = 18.3, OR = 0.64, P = 1.87 × 10⁻⁵) and rs12484776 from TNRC6B (χ² = 19.7, OR = 1.40, P = 8.91 × 10⁻⁶), were identified as significantly associated with the disease status of UL. Rs2280543 was significantly associated with the number of fibroid nodes (P = 0.0007), while rs12484776 was significantly associated with node size (χ² = 54.88, P = 3.44 × 10⁻¹¹). Both SNPs were a significant eQTL for their genes. In this study, we have shown that both BET1L and TNRC6B contributed to the risk of UL in Chinese women. Significant SNPs from BET1L and TNRC6B were also identified as significantly associated with the number of fibroid nodes and the size of the node, respectively.

Uterine fibroids - what's new?

Uterine fibroids are the commonest benign tumours of women and affect all races with a cumulative lifetime risk of around 70%. Despite their high prevalence and the heavy economic burden of treatment, fibroids have received remarkably little attention compared to common female malignant tumours. This article reviews recent progress in understanding the biological nature of fibroids, their life cycle and their molecular genetic origins. Recent progress in surgical and interventional management is briefly reviewed, and medical management options, including treatment with selective progesterone receptor modulators, are also discussed.

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.

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.

Association of polymorphisms and haplotypes in the cytochrome P450 1B1 gene with uterine leiomyoma: A case control study

Uterine leiomyoma (UL) is an estrogen-dependent neoplasm of the uterus and estrogen metabolizing enzymes affect its promotion and progression. The aim of the present study was to evaluate the association between four single-nucleotide polymorphisms (SNPs) of the cytochrome P450 1B1 (CYP1B1) gene and UL risk. Four SNPs of the CYP1B1 gene in 105 UL patients and 112 unrelated healthy controls were genotyped using a direct sequencing method. Haplotype analyses were performed with UNPHASED software and linkage disequilibrium (LD) was assessed by Haploview software. There were no associations between Leu432Val (rs1056836), Asp449Asp (rs1056837) and Asn453Ser (rs1800440) polymorphisms of the CYP1B1 gene and UL. Although the genotypic frequencies of the Arg368His (rs79204362) polymorphism did not differ between the two groups, the frequency of A (His) allele was significantly higher in UL females (P=0.02). In addition, the frequency of GTAA haplotype was significantly higher in the controls and played a protective role in UL susceptibility. A strong LD between the three common SNPs (rs1056836, rs1056837 and rs1800440) in the CYP1B1 gene was observed in the population. In conclusion, a higher frequency of the CYP1B1 368His (A) allele was observed in UL females. The frequency of the GTAA haplotype was significantly higher in healthy females and this haplotype played a protective role in UL susceptibility.

Self-reported family history of leiomyoma: not a reliable marker of high risk

PURPOSE

To examine the importance of self-reported family history of uterine leiomyoma (fibroids) as a marker of risk.

METHODS

Women, aged 35 to 49, were randomly selected from the membership of a large, urban health plan. Participants completed a self-administered questionnaire about family history of fibroids. Ultrasound screening for fibroids followed, regardless of whether participants had been previously diagnosed (660 black, 412 white). Data for each ethnic group were analyzed separately using Poisson regression.

RESULTS

In both ethnic groups, women who reported a family history of fibroids had an elevated risk of fibroids compared with those without family history. However, no elevated risk was apparent for cases who did not know they had fibroids when they reported the family history information.

CONCLUSIONS

Many women may first learn about their family history of fibroids when discussing their own clinical diagnosis with family members. Such bias would invalidate self-reported family history as a predictor of fibroid risk. As new pharmacologic treatments for fibroids are developed, women at high risk of fibroids would benefit from early screening and pharmacologic treatment to delay development of large fibroids and reduce the need for invasive treatments. Self-reported family history is not useful for identifying high-risk women.

BET1L and TNRC6B associate with uterine fibroid risk among European Americans

Uterine fibroid (UFs) affect 77 % of women by menopause and account for $9.4 billion in healthcare costs each year. Although UFs are heritable, genetic risk is poorly understood. The first genome-wide association study (GWAS) of UFs was recently performed in a Japanese population, with reported genome-wide significance for single nucleotide polymorphisms (SNPs) across three chromosomal regions. We tested these SNPs for association with UFs in US cohorts. Women were enrolled in the Right from the Start (RFTS) cohort and the BioVU DNA repository. UF status in both cohorts was determined by pelvic imaging. We tested 65 candidate and haplotype-tagging SNPs for association with UFs presence using logistic regression in RFTS and the top three GWAS-associated SNPs in BioVU. We also combined association results from both cohorts using meta-analysis. 1,086 European American (EA) cases and 1,549 controls were examined. Two SNP associations replicated [blocked early in transport 1 homolog (BET1L) rs2280543, RFTS-BioVU meta-odds ratio (OR) = 0.67 95 % confidence interval (CI) 0.38-0.96, Q = 0.70, I = 0, p = 6.9 × 10⁻³; trinucleotide repeat containing 6B (TNRC6B) rs12484776, RFTS-BioVU meta-OR = 1.21, 95 % CI 1.07-1.35, Q = 0.24, I = 28.37, p = 8.7 × 10⁻³). Meta-analyses combining evidence from RFTS, BioVU, and prior GWAS showed little heterogeneity in effect sizes across studies, with meta-p values between 7.45 × 10⁻⁸ and 3.89 × 10⁻⁹, which were stronger than prior GWAS and supported associations observed for all previously identified loci. These data suggest common variants increase risk for UF in both EA and Japanese populations. However, further research is needed to assess the role of these genes across other racial groups.

Variants in BET1L and TNRC6B associate with increasing fibroid volume and fibroid type among European Americans

Uterine fibroids (UFs) affect 77 % of women by menopause and account for $9.4 billion in yearly healthcare costs. We recently replicated findings from the first UF genome-wide association study (GWAS), conducted in the Japanese. Here we tested these GWAS-discovered SNPs for association with UF characteristics to further assess whether risk varies by sub-phenotypes of UFs. Women were enrolled in Right from the Start (RFTS) and the BioVU DNA repository (BioVU). UF status was determined by pelvic imaging. We tested the top GWAS-associated SNPs for association with UF characteristics (RFTS: type, number, volume; BioVU: type) using covariate adjusted logistic and linear regression. We also combined association results of UF type using meta-analysis. 456 European American (EA) cases and 1,549 controls were examined. Trinucleotide repeat containing 6B (TNRC6B) rs12484776 associated with volume in RFTS (β = 0.40, 95 % CI 0.05-0.75, p = 0.024). RFTS analyses evaluating stratified quartiles of volume showed the strongest OR at rs12484776 for the largest volume (16.6-179.1 cc, odds ratio (OR) = 2.19, 95 % confidence interval (CI) 1.07-4.46, p = 0.031). Meta-analysis showed a strong association at blocked early in transport 1 homolog (BET1L) rs2280543 for intramural UFs (meta-OR = 0.51, standard error (SE) = 0.14, Q = 0.590, I = 0, p = 2.48 × 10(-6)), which is stronger than the overall association with UF risk. This study is the first to evaluate these SNPs for association with UF characteristics and suggests these genes associate with increasing UF volume and protection from intramural UF in EAs.

African ancestry and genetic risk for uterine leiomyomata

Rates of uterine leiomyomata (UL) are 2-3 times higher in African Americans than in European Americans. It is unclear whether inherited factors explain the ethnic disparity. To investigate the presence of risk alleles for UL that are highly differentiated in frequency between African Americans and European Americans, the authors conducted an admixture-based genome-wide scan of 2,453 UL cases confirmed by ultrasound or surgery in the Black Women's Health Study (1997-2009), a national prospective cohort study. Controls (n = 2,102) were women who did not report a UL diagnosis through 2009. Mean percentage of European ancestry was significantly lower among cases (20.00%) than among controls (21.63%; age-adjusted mean difference = -1.76%, 95% confidence interval: -2.40, -1.12; P < 0.0001), and the association was stronger in younger cases. Admixture analyses showed suggestive evidence of association at chromosomes 2, 4, and 10. The authors also genotyped a dense set of tag single nucleotide polymorphisms at different loci associated with UL in Japanese women but failed to replicate the associations. This suggests that genetic variation for UL differs in populations with and without African ancestry. The admixture findings further indicate that no single highly differentiated locus is responsible for the ethnic disparity in UL, raising the possibility that multiple variants jointly contribute to the higher incidence of UL in African Americans.

Review article: late post-hysterectomy ectopic pregnancy

Ectopic pregnancy after hysterectomy is a rare but potentially life-threatening condition requiring prompt diagnosis to prevent the increased mortality associated with rupture. Twenty-seven cases of late post-hysterectomy ectopic pregnancy reported in the English literature since 1918 were reviewed and analysed for presenting symptoms, missed diagnosis rate at initial presentation, location of ectopic and rupture rate at diagnosis. The presenting symptoms were found to be non-specific. The diagnosis in this population is twice more likely to be missed than in women with intact uteri. The rupture rate is 63%, compared with 37% in women with intact uteri. The majority of late post-hysterectomy ectopic pregnancies (62%) were located in the fallopian tubes. Because of the potential risk of mortality, emergency physicians should always consider the possibility of ectopic pregnancy in childbearing women whose surgical history includes hysterectomy without oophorectomy. Evaluation of abdominal pain in this population should include a pregnancy test to ensure prompt diagnosis when the possibility of pregnancy exists clinically.

Genetics of early cancer detection behaviours in Australian female twins

Early detection of cervical and breast cancers is an important component of women's health strategy. Screening programmes, health professional interventions and preventive behaviours such as breast self-examination provide the means to this end. Our twin study sought to identify the relative influence of environmental and genetic factors on liability to early cancer detection behaviours, including use of cervical smear tests, mammograms, and breast examination. Additive genetic and random environmental effects models gave the best, most parsimonious fit to the data for each early cancer detection behaviour. The heritability of liability to Pap smear use was 66%, mammogram use 50%, breast examination by a doctor or nurse 38% and breast self-examination 37%. Genetic influences were behaviour-specific; there was no evidence for a common genetic influence on the four behaviours. Potential covariates investigated included age, amount of contact between co-twins, educational level and personality traits such as harm avoidance, novelty seeking, reward dependence, neuroticism, anxiety, depression, self-esteem, perceived control, interpersonal dependency and ways of coping. None were significant. The study was carried out before the implementation of national screening programmes with media campaigns to increase participation rates. Hence follow-up investigation, including data on regularity of behaviours, would be informative

A genome-wide association study identifies three loci associated with susceptibility to uterine fibroids

Uterine fibroids are a common benign tumor of the female genital tract. We conducted a genome-wide association study in which 457,044 SNPs were analyzed in 1,607 individuals with clinically diagnosed uterine fibroids and 1,428 female controls. SNPs showing suggestive associations (P < 5 × 10(-5)) were further genotyped in 3,466 additional cases and 3,245 female controls. Three loci on chromosomes 10q24.33, 22q13.1 and 11p15.5 revealed genome-wide significant associations with uterine fibroids. The SNPs showing the most significant association in a combination analysis at each of these loci were rs7913069 (P = 8.65 × 10(-14), odds ratio (OR) = 1.47), rs12484776 (P = 2.79 × 10(-12), OR = 1.23) and rs2280543 (P = 3.82 × 10(-12), OR = 1.39), respectively. Subsequent fine mapping of these regions will be necessary to pinpoint the causal variants. Our findings should shed light on the pathogenesis of uterine fibroids.

Detection of somatic mutations and germline polymorphisms in mitochondrial DNA of uterine fibroids patients

To identify the role of mitochondrial DNA (mtDNA) mutations in uterine fibroids patients, genomic DNA isolated from paired myometrium and fibroid tissues was screened for mutations. The present study represents the first investigation to report that 10.4% of uterine fibroids cases had either mtDNA mutations or polymorphisms or both. Among the 14 mitochondrial sequence variants identified, seven are somatic mutations (A3327C, G3352A, G3376A, G3380A, G3421A, T15312G, and C15493G) and the remaining (G3316A, C3342A, C3442T, T10205A, A10188G, A10229C, and A10301T) are gene polymorphisms. Somatic mutations were both homo- and heteroplasmic in nature. Of the seven somatic mutations located in the MTND1 and MTCYB genes, five (71.42%) are nonsynonymous in nature, whereas four (57.14%) of the polymorphisms located in MTND1 and MTND3 genes are found to be nonsynonymous. Sequence variants such as G3380A, G3421A, T15312G, G3376A, and G3316A have been earlier described in different human pathologies, but the remaining are novel ones. Mitochondrial somatic mutations and polymorphisms may predispose women to an earlier onset of degenerative cellular processes, which impair oxidative phosphorylation capacity and thereby promote tumorigenesis in uterine smooth muscle cells. Detection of mtDNA sequence variations in fibroid patients raises the need for larger case-control studies to screen the whole mitochondrial genome and evaluate as a future diagnostic biomarker in fibroid patients.

Advances in the management of uterine fibroids

Uterine fibroids are extremely common, with major surgery the current main management option; uterine artery embolisation is an alternative, but risks to fertility are unclear. Minimally invasive procedures are becoming more commonly performed via both the hysteroscope and laparoscope, minimising recovery time for patients. Recently, small doses of progesterone receptor modulators (mifepristone and asoprisnil) have been shown to be effective in reducing menstrual blood loss and fibroid size. Progress from here should include the development of a well-tolerated oral preparation that will maintain fertility.

Uterine leiomyomata and decreased height: a common HMGA2 predisposition allele

Uterine leiomyomata (UL) are the most common female pelvic tumors and the primary indication for hysterectomy in the United States. We assessed genetic liability for UL by a known embryonic proliferation modulator, HMGA2, in 248 families ascertained through medical record-confirmed affected sister-pairs. Using a (TC)( n ) repeat in the 5' UTR and 17 SNPs spanning HMGA2, permutation-based association tests identified a significant increase in transmission of a single TC repeat allele (TC227) with UL (allele-specific P = 0.00005, multiple testing corrected min-P = 0.0049). The hypothesis that TC227 is a pathogenic variant is supported by a trend towards higher HMGA2 expression in TC227 allele-positive compared with non-TC227 UL tissue as well as by absence of culpable exonic sequence variants. HMGA2 has also been suggested recently by three genome-wide SNP studies to influence human height variation, and our examination of the affected sister-pair families revealed a significant association of TC227 with decreased height (allele-specific P = 0.00033, multiple testing corrected min-P = 0.016). Diminished stature and elevated risk of UL development have both been correlated with an earlier age of menarche, which may be the biological mechanism for TC227 effects as a tendency of women with TC227 to have an earlier onset of menarche was identified in our study population. These results indicate HMGA2 has a role in two growth-related phenotypes, UL predisposition and height, of which the former may affect future medical management decisions for many women.

Benign gynecologic conditions

Benign gynecologic conditions constitute the majority of the general gynecologist's practice. Along with health maintenance examinations, contraceptive management, family planning issues, and concerns about incontinence, the gynecologic conditions for which patients commonly present include adnexal masses, leiomyomata, endometriosis, and pelvic inflammatory disease. This article addresses each of these last four entities and incorporates a discussion of their etiologies, clinical presentations, keys to diagnosis, and the various treatment options available.

Incidence, aetiology and epidemiology of uterine fibroids

Uterine fibroids are the most common benign tumour of the female genital tract. However, their true prevalence is probably under-estimated, as the incidence at histology is more than double the clinical incidence. Recent longitudinal studies have estimated that the lifetime risk of fibroids in a woman over the age of 45 years is more than 60%, with incidence higher in blacks than in whites. The cause of fibroids remains unclear and their biology poorly understood. No single candidate gene has been detected for commonly occurring uterine fibroids. However, the occurrence of rare uterine fibroid syndromes, such as multiple cutaneous and uterine leiomyomatosis, has been traced to the gene that codes for the mitochondrial enzyme, fumarate hydratase. Cytogenetic abnormalities, particularly deletions of chromosome 7, which are found in up to 50% of fibroid specimens, seem to be secondary rather than primary events, and investigations into the role of tumour suppressor genes have yielded conflicting results. The key regulators of fibroid growth are ovarian steroids, both oestrogen and progestogen, growth factors and angiogenesis, and the process of apoptosis. Black race, heredity, nulliparity, obesity, polycystic ovary syndrome, diabetes and hypertension are associated with increased risk of fibroids, and there is emerging evidence that familial predisposition to fibroids is associated with a distinct pattern of clinical and molecular features compared with fibroids in families without this prevalence.

The impact of race as a risk factor for symptom severity and age at diagnosis of uterine leiomyomata among affected sisters

OBJECTIVE

The objective of the study was to identify risk factors for uterine leiomyomata (UL) in a racially diverse population of women with a family history of UL, and to evaluate their contribution to disease severity and age at diagnosis.

STUDY DESIGN

We collected and analyzed epidemiologic data from 285 sister pairs diagnosed with UL. Risk factors for UL-related outcomes were compared among black (n = 73) and white (n = 212) sister pairs using univariate and multivariate regression models.

RESULTS

Black women reported an average age at diagnosis of 5.3 years younger (SE, 1.1; P < .001) and were more likely to report severe disease (odds ratio, 5.22; 95% confidence interval, 1.99-13.7, P < .001) than white women of similar socioeconomic status.

CONCLUSION

Self-reported race is a significant factor in the severity of UL among women with a family history of UL. Differences in disease presentation between races likely reflect underlying genetic heterogeneity. The affected sister-pair study design can address both epidemiological and genetic hypotheses about UL.

Genetic heterogeneity among uterine leiomyomata: insights into malignant progression

Uterine leiomyomata (UL), also known as fibroids, are the most common pelvic tumors in women of reproductive age and are the primary indication for hysterectomy in the USA. Many lines of evidence indicate a strong genetic component to the development of these tumors. In fact, approximately 40% of UL have non-random, tumor-specific chromosome abnormalities which have allowed classification into well-defined subgroups (deletion of portions of 7q, trisomy 12 or rearrangements of 12q15, 6p21 or 10q22) as well as identification of candidate genes for UL predisposition. Although benign, UL have been linked to malignancy through two genomic regions on chromosome 1. Mutation of fumarate hydratase (FH) at 1q43 is known to cause the Mendelian syndromes of multiple cutaneous and uterine leiomyomata (MCL) and hereditary leiomyomatosis and renal cell cancer (HLRCC), and recently, FH mutations have been detected in some non-syndromic UL. In addition, transcriptional profiling suggests that loss of the short arm of chromosome 1 in cellular leiomyomata, an uncommon histological variant of UL, may account in part for the presumed yet rare malignant transformation of UL to uterine leiomyosarcoma.

The second National Institutes of Health International Congress on advances in uterine leiomyoma research: conference summary and future recommendations

OBJECTIVE

To summarize the proceedings of the Advances in Uterine Leiomyoma Research: 2nd NIH International Congress, which was convened on February 24-25, 2005 by the Department of Health and Human Services (DHHS), National Institutes of Health (NIH) in Bethesda, Maryland.

DESIGN

Scientific information was presented at a 2-day conference, which was a collaborative effort of agencies across the DHHS and members of the academic, clinical, and medical communities involved in uterine leiomyoma research.

CONCLUSION(S)

The conference brought together scientists in biomedicine, epidemiology, basic research, therapeutics, and translational medicine and fostered an exchange of scientific information among members of the uterine leiomyoma research and health care communities. This document summarizes this exchange and outlines research needs and recommendations for future research directions.

The genetic heterogeneity of uterine leiomyomata

Research investigating the genetics of UL has already been successful in gathering epidemiologic evidence for heritability, establishing the clonal and mosaic nature of these tumors, correlating genotypic and phenotypic characteristics, defining cytogenetic subgroups, and identifying specific genes involved in tumorigenesis. Although UL are known to be benign tumors, the impact they have on the lives of so many women can only be described as "malignant". For this reason, continuing the quest to ascertain the genes, functions, and mechanisms integral to UL development is absolutely imperative. Genetic tests for personalized medical management of women with fibroids is at the threshold for providing the most appropriate treatments (Fig. 3), and combined with developing less invasive therapies portends a brighter future for a major health problem for women.

Future directions in myoma research

This article highlights our current knowledge of fibroids and addresses future directions for fibroid research and treatment over the next decade. The available data on cytogenetics are discussed, in addition to discoveries into signaling pathways and second messenger molecules in leiomyomas. Current medical management, surgical trends and the barriers to transition to minimally invasive procedures are summarized. Innovations in genetic diagnosis and interventional radiologic-aided therapies may revolutionize therapy for certain populations of patients who have fibroids. From tissue-specific medical management, to minimally invasive surgical techniques, to pharmacogenetics, the current directions of fibroid research are leading us to an exciting new frontier.

The genetics of uterine leiomyomata: what clinicians need to know

The genetics of many complex diseases, including hypertension, diabetes, and asthma, are receiving intense investigation and beginning to have therapeutic relevance. Family medical history can be a critical source of information for providing optimal patient care. For gynecologists, knowledge of cancer susceptibility genes such as BRCA1 and BRCA2 and the genetic syndrome hereditary nonpolyposis colorectal cancer (Lynch syndrome II) affects how patients are screened for ovarian and endometrial cancers. Similarly, identification of mutations in the fumarate hydratase (FH) gene that lead to a syndrome called hereditary leiomyomatosis and renal cell carcinoma (HLRCC) will impact screening and treatment of women with uterine leiomyomas. Hereditary leiomyomatosis and renal cell carcinoma syndrome is particularly relevant to clinicians and patients because of the resulting increased risk of malignant disease for both the affected woman and her family. The goals of this article are to summarize the evolving genetic information concerning uterine leiomyomas, including hereditary leiomyomatosis and renal cell carcinoma syndrome, and to discuss the clinical importance of these findings. The current role of family medical history and future implications of genes relevant to leiomyoma biology will be reviewed.

A prospective study of hypertension and risk of uterine leiomyomata

Although uterine leiomyomata (also known as fibroids or myomas) affect the reproductive health and well-being of approximately 25% of premenopausal women, risk factors are poorly understood. Elevated diastolic blood pressure may increase fibroid risk through uterine smooth muscle injury, not unlike atherosclerosis. The authors prospectively examined the relation between diastolic blood pressure and incidence of clinically detected leiomyomata. The sample included 104,233 premenopausal nurses from 14 US states enrolled in the Nurses' Health Study II. Participants, aged 25-42 years, had intact uteri and no history of cancer or fibroids at enrollment in 1989. During the 827,348 woman-years of follow-up (1989-1999), 7,466 incident diagnoses of uterine leiomyomata, confirmed by ultrasound or hysterectomy, were reported. With a multivariable Cox proportional hazards model, the relative risk of self-reported ultrasound- or hysterectomy-confirmed uterine leiomyomata according to diastolic blood pressure in 1989 and time-varying antihypertensive use was estimated. With adjustment for age, race/ethnicity, body mass index, and reproductive history covariates, for every 10-mmHg increase in diastolic blood pressure, the risk of fibroids rose 8% (5-11%) and 10% (7-13%) among nonusers and users of antihypertensive medications, respectively. Elevated blood pressure has an independent, positive association with risk for clinically detected uterine leiomyomata among premenopausal women. Investigating this association may suggest possible pathways to prevent fibroids.

Gene expression studies provide clues to the pathogenesis of uterine leiomyoma: new evidence and a systematic review

BACKGROUND

Uterine leiomyomas are extremely common and a major cause of pelvic pain, bleeding, infertility, and the leading indication for hysterectomy. Familial and epidemiological studies provide compelling evidence that genetic alterations play an important role in leiomyoma development.

METHODS

Using Affymetrix U133A GeneChip we analysed expression profiles of 22,283 genes in paired samples of leiomyoma and adjacent normal myometrium. We compared our results with previously published data on gene expression in uterine leiomyoma and identified the overlapping gene alterations.

RESULTS

We detected 80 genes with average differences of > or = 2-fold and false discovery rates of < 5% (14 overexpressed and 66 underexpressed). A comparative analysis including eight previous gene expression studies revealed eight prominent genes (ADH1, ATF3, CRABP2, CYR61, DPT, GRIA2, IGF2, MEST) identified by at least five different studies, eleven genes (ALDH1, CD24, CTGF, DCX, DUSP1, FOS, GAGEC1, IGFBP6, PTGDS, PTGER3, TYMS) reported by four studies, twelve genes (ABCA, ANXA1, APM2, CCL21, CDKN1A, CRMP1, EMP1, ESR1, FY, MAP3K5, TGFBR2, TIMP3) identified by three studies, and 40 genes reported by two different studies.

CONCLUSIONS

Review of gene expression data revealed concordant changes in genes regulating retinoid synthesis, IGF metabolism, TGF-beta signaling and extracellular matrix formation. Gene expression studies provide clues to the relevant pathways of leiomyoma development.

Involvement of fumarate hydratase in nonsyndromic uterine leiomyomas: genetic linkage analysis and FISH studies

Recently, germline mutations of the fumarate hydratase (FH) gene, in 1q42.1, have been found to be involved in syndromes associated with uterine leiomyomas (ULs). Compelling evidence also supports a genetic liability to develop nonsyndromic UL, although susceptibility genes have not been reported to date. Loss of heterozygosity (LOH) studies have found no or rare evidence of LOH of FH in nonsyndromic UL. However, the karyotypes of these tumors were not reported, and cytogenetic aberrations of 1q42-44 have been observed infrequently in UL. To determine whether FH mutations also may predispose women to developing nonsyndromic UL, we performed a genetic linkage study with DNA from 123 families containing at least one affected sister pair. In addition, to assess the frequency of FH loss specifically in UL with 1q rearrangements, we performed a fluorescence in situ hybridization (FISH) analysis of UL with 1q rearrangements. Analysis of the genotyping data revealed evidence suggestive of linkage to the FH region among study participants who were less than 40 years of age at diagnosis (Zlr 1.7 at D1S547, P = 0.04). FISH results showed that one copy of FH was absent in 9 of 11 ULs. These data indicate that loss of FH might be a significant event in the pathogenesis of a subset of nonsyndromic ULs.

Etiology and pathogenesis of uterine leiomyomas: a review

Uterine leiomyomas, or fibroids, represent a major public health problem. It is believed that these tumors develop in the majority of American women and become symptomatic in one-third of these women. They are the most frequent indication for hysterectomy in the United States. Although the initiator or initiators of fibroids are unknown, several predisposing factors have been identified, including age (late reproductive years), African-American ethnicity, nulliparity, and obesity. Nonrandom cytogenetic abnormalities have been found in about 40% of tumors examined. Estrogen and progesterone are recognized as promoters of tumor growth, and the potential role of environmental estrogens has only recently been explored. Growth factors with mitogenic activity, such as transforming growth factor- (subscript)3(/subscript), basic fibroblast growth factor, epidermal growth factor, and insulin-like growth factor-I, are elevated in fibroids and may be the effectors of estrogen and progesterone promotion. These data offer clues to the etiology and pathogenesis of this common condition, which we have analyzed and summarized in this review.

Relative importance of female-specific and non-female-specific effects on variation in iron stores between women

Women have lower iron stores than men because of iron loss during their reproductive years. However, variation between women could result from differences in iron loss, aspects of iron homeostasis common to men and women, or a combination of both. We compared the effects of age, menopause, menstrual blood loss and the number of pregnancies (sex-specific factors), and the effects of genetic variation, on markers of iron stores. We assessed how much the same genes or other familial factors influence iron status in both men and women. Data from 2,039 female twins who participated in studies of reproductive health and iron status were used to estimate the proportions of variation that could be ascribed to genes, environment and measured factors. Significant effects of age, menopausal status and magnitude of menstrual blood loss were demonstrated, accounting for up to 18% of variance in serum ferritin in this sample, but number of children had no significant effect. Genetic effects were more than twice as great as sex-specific effects. The within-pair similarity of ferritin values in dizygotic female twin pairs was greater than for dizygotic opposite-sex pairs, but this difference was not quite significant, consistent with a minor role for sex-specific factors; and the opposite-sex within-pair differences did not diminish significantly with age. We conclude that the contribution of genetic differences between women to variation in iron stores outweighs the comparatively small effects of interindividual variation in iron loss through variation in menstruation and number of pregnancies.

The International Endogene Study: a collection of families for genetic research in endometriosis

OBJECTIVE

The aim of the International Endogene Study is to discover genes that influence susceptibility to endometriosis.

DESIGN

The study brings together two research groups based in Australia and the United Kingdom that independently have been collecting families for linkage analysis and candidate gene studies. Both groups used similar methods to recruit families, obtain clinical notes, assign disease status based on the operative records and available histology, and collect common clinical data including age at onset of symptoms, age at diagnosis, and symptoms experienced.

SETTING

Recruitment has been mainly from Australia, the United Kingdom, and the United States.

PATIENT(S)

All affected participants have surgically confirmed disease.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Clinical and epidemiological data.

RESULT(S)

To date, >1,100 families with affected sisters have been recruited, and >1,200 triads (affected women and both parents), for case-control studies.

CONCLUSION(S)

We have created the largest resource yet assembled of clinical data and DNA for linkage and association studies in endometriosis. The increase in power to detect susceptibility genes vindicates the decision to merge the two studies and demonstrates the value of large-scale international collaboration.

Protective effect of pregnancy for development of uterine leiomyoma

Many factors that can modulate the risk of developing uterine leiomyoma have been identified, including parity. Epidemiological data on decreased risk of developing this disease has been subject to different interpretations regarding whether pregnancy per se is protective or, as leiomyomas are a major cause of infertility, women that develop these tumors are less fertile and thus have lower pregnancy rates. We have utilized an animal model genetically predisposed to uterine leiomyoma to investigate the potential protective effect of pregnancy on the risk of developing this disease. Female Eker rats that carry a mutation in the tuberous sclerosis 2 (Tsc-2) tumor suppressor gene develop uterine leiomyoma with a frequency of 65% when nulliparous. These animals were bred with intact or vasectomized males and tumor incidence determined after a single pregnancy (to confirm fertility) or multiple pregnancies over the lifetime of the animals. Females with multiple litters displayed a dramatic shift in tumor incidence and presentation. Tumor incidence decreased from 71% in single litter females to 10% in females that had multiple litters (average: five litters/animal). Interestingly, females bred with vasectomized males also exhibited a reduced tumor incidence of 41%, suggesting that the hormonal changes associated with early stages of pregnancy that occur in pseudopregnant females may have contributed to the protective effect of pregnancy.

Uterine fibroids

Uterine leiomyomas (fibroids or myomas), benign tumours of the human uterus, are the single most common indication for hysterectomy. They are clinically apparent in up to 25% of women and cause significant morbidity, including prolonged or heavy menstrual bleeding, pelvic pressure or pain, and, in rare cases, reproductive dysfunction. Thus, both the economic cost and the effect on quality of life are substantial. Surgery has been the mainstay of fibroid treatment, and various minimally invasive procedures have been developed in addition to hysterectomy and abdominal myomectomy. Formation of new leiomyomas after these conservative therapies remains a substantial problem. Although medications that manipulate concentrations of steroid hormones are effective, side-effects limit long-term use. A better approach may be manipulation of the steroid-hormone environment with specific hormone antagonists. There has been little evidence-based evaluation of therapy. New research into the basic biology of these neoplasms may add new treatment options for the future as the role of growth factors and genetic mutations in these tumours are better understood.

Factors associated with hysterectomy among women in Australia

This study was to identify hysterectomy prevalence across urban, rural and remote areas of Australia and across states, to separate geographic variation from the effect of sociodemographic influences, and also to compare the quality of life of women who have and have not had hysterectomy. Data were collected from 14,072 women aged 45-50 years participating in the baseline survey of the Australian Longitudinal Study on Women's Health. The estimated prevalence of hysterectomy was 22%. Factors significantly associated with hysterectomy included living in a rural or remote area, state of residence, having private health insurance, lower levels of education, being married and having more than two children, having had other gynaecological and non-gynaecological surgical procedures, and more visits to general practitioners. Compared with women who had not had hysterectomy, women who had had hysterectomy had significantly poorer physical and mental health as measured by the SF-36 quality of life profile (adjusted mean PCS=45.7 vs 49.3, p<0.0001; adjusted mean MCS=46.9 vs 48.2, p<0.0001).

Heritability and risk factors of uterine fibroids--the Finnish Twin Cohort study

OBJECTIVES

Our aim was to study heritability, risk factors and hospitalization for uterine fibroids.

METHODS

A random sample of 80 MZ and 80 DZ twins from the Finnish Twin Cohort were invited and 51% of the eligible women (n=82, 17 MZ and 16 DZ pairs, 40-47 years, mean age 43.0), underwent a transvaginal ultrasound. The entire cohort of 13872 women was linked to the national hospital discharge registry 1972-1990.

RESULTS

Prevalence of fibroids was 66% and the average number of fibroids 1.7. The casewise concordance for being hospitalized for uterine fibroids was higher in MZ (0.31, 95% CI 0.24-0.37) than in DZ pairs (0.18, 95% CI 0.14-0.22). The proportion of variance in liability to fibroid hospitalization accounted for by genetic factors was 54.8% (95% CI 46.2-62.7%). Women with fibroids had higher body mass index (23.7 vs 21.7, P=0.0086), lower age at first birth (25.7 vs 29.3, P=0.012) and higher parity (3+ children 48.2 vs 29.6%, P=0.009) than women without fibroids. Risk ratio (RR) for fibroids in a MZ twin whose sister had been diagnosed with fibroids was 1.1 (95% CI 0.08;15), for a DZ twin 1.1 (95% CI 0.16;8.8) and for all twins 1.3 (95% CI 0.3; 6.1). Intraclass correlation for the number of fibroids was 0.24 for MZ and 0.11 for DZ twins, yielding an heritability estimate of 0.26.

CONCLUSION

Reproductive and anthropometric factors may have at least as large role in pathogenesis of fibroids than genetic factors.

Birth weight and age at menopause in Australian female twin pairs: exploration of the fetal origin hypothesis

In a twin sample where duration of gestation can be controlled, a specific example of the fetal origins hypothesis concerning association between low birth weight and early age at menopause is explored. The hypothesis is based on the physiologically plausible path from intrauterine growth retardation and reduced numbers of primary follicles to an earlier menopause. The sample comprised 323 Australian female twin pairs where both co-twins had reached menopause naturally and reported on their weight at birth. Regression analysis showed no linear association between the two variables (P = 0.371, r(2) = 0.0009). Intra-pair differences in age at menopause were investigated in the context of relative birth weight of co-twins. In 265 pairs an intra-pair birth weight difference was reported. In monozygotic (MZ) pairs (n = 168) this allowed for control of genetic effects as well as gestation duration. No significant differences dependent on birth weight relative to co-twin were found for age at natural menopause in either MZ or dizygotic (DZ) twin pairs, even in pairs whose birth weights differed markedly. There was some indication that twins with premature ovarian failure were heavier at birth than twins with normal or later menopausal age. We conclude that the hypothesis that lower birth weight is associated with earlier menopause is not supported by our data.

Predictors of hysterectomy: an Australian study

OBJECTIVE

We evaluated the relative importance of predictors of hysterectomy.

STUDY DESIGN

A questionnaire survey of an Australia-wide sample of adult female twins was conducted; self-report data were validated against reports from treating physicians.

RESULTS

A total of 3096 women (94%) and 366 physicians (87%) responded. The sensitivity of patient report of hysterectomy was 98.2%. Best predictors of hysterectomy were endometriosis (odds ratio 4.85, 95% confidence interval 3.17-7.43), medical consultation for menorrhagia (odds ratio 3.55, 95% confidence interval 2.47-5.12), joint effects of fibroids with medical consultation for chronic or persisting pelvic pain (odds ratio 3.34, 95% confidence interval 1. 42 to 7.87), having smoked >40 cigarettes per day (odds ratio 3.24, 95% confidence interval 1.10-9.55), joint effects of fibroids with consultation for menstrual problems (odds ratio 2.61, 95% confidence interval 1.36-5.01), and tubal ligation (odds ratio 1.77, 95% confidence interval 1.31-2.39). Less-important predictors were age and higher education level (protective).

CONCLUSION

Consulting a physician about pelvic pain and menstrual problems, especially heavy bleeding, are recognized steps toward hysterectomy. Of particular interest for future genetic analyses are the high odds of hysterectomy for women with endometriosis, fibroids, or menorrhagia.