FMR1-dependent variability of ovarian aging patterns is already apparent in young oocyte donors

A Systematic Review of Genetics and Reproductive Health Outcomes: Asian Perspective

In the last four decades, advances in assisted reproductive technology (ART) have offered hope to individuals with fertility problems to conceive. However, a closer examination of the clinical outcomes of ART shows a stark contrast in Asian women compared to Caucasians, with majority of studies reporting lower reproductive success among Asian women. We performed a systematic review to elucidate the genes associated with ART clinical outcomes, with a focus on Asian ethnicities. We completed a database search to identify all studies associated with reproductive outcomes in women of different ethnic backgrounds. Following PRISMA, 128 studies were analyzed. Pathway analysis of gene sets was done using Cytoscapev3.4.0. We observed that age at menarche (AAM) was correlated with the timing of the first pregnancy, with Hawaiians having the lowest age (22.2 years) and Japanese the highest age (25.0 years). LIN28 mutations were associated with AAM and prevalent in both Chinese and American populations. FMR1 was most associated with ovarian reserve. Network analysis highlighted a close association between FMR1, FSHR, ESR1, BMP15, and INHA, through biological functions affecting menstrual cycle and hypothalamic-pituitary axis and therefore ovarian follicle development. Leveraging these findings, we propose the development of a personalized, ethnic-specific biomarker panel which would enhance patient stratification to address every woman's unique reproductive potential.

The association of FMR1 gene (CGG)n variation with idiopathic female infertility

INTRODUCTION

The FMR1 gene plays an important role in brain development and in the regulation of ovarian function. The FMR1 gene contains CGG repeat variation and the expansion of the repeats is associated with various phenotypes e.g. fragile X syndrome, premature ovarian failure, etc. Repeats ranging < 55 CGG are considered normal, however recent studies suggest that high-normal (35-54 CGG) and low-normal (< 26 CGG) alleles may also have an impact on female reproductive function.

MATERIAL AND METHODS

We have performed a case-control study to assess the impact of FMR1 gene CGG repeats on female infertility. The study comprised 161 women with primary and secondary idiopathic infertility and 12 females with diminished ovarian reserve. The control group consisted of 129 healthy women with children. The FMR1 gene trinucleotide CGG repeat variation was detected using a triplet repeat primed polymerase chain reaction with capillary electrophoresis.

RESULTS

The analysis of CGG repeats revealed that high-normal alleles are statistically significantly more common in the secondary infertility group than in controls (12% vs. 4.3%, p = 0.03, OR = 3.1, 95% CI: 1.1-8.3). The distribution of high-normal alleles and genotypes did not differ between patients with primary infertility and controls (p > 0.05). In addition, the analysis of low-normal allele and genotype frequencies did not present a difference between primary, secondary infertility and the control group (p > 0.05).

CONCLUSIONS

In our study, the FMR1 gene high-normal alleles were associated with secondary infertility. However, to address the controversies related to the role of FMR1 genes in the development of diminished ovarian reserve, further studies on the subject are required.

Effect of race and ethnicity on utilization and outcomes of assisted reproductive technology in the USA

BACKGROUND

The purpose of this study was to determine the utilization and live birth rates of assisted reproductive technology (ART) modalities among various racial and ethnic groups in recent years.

METHODS

We reviewed ART data reported to the Society for Assisted Reproductive Technologies Clinic Outcome Reporting System (SART CORS) for autologous ART and third-party ART (3ART) cycles which involved donor oocytes, sperm, embryos and gestational carrier, performed in the U.S. between 2004 and 2013. To gauge demand by various racial/ethnic groups for ART services, we examined fertility rates and demographics of the entire U.S. birth cohort over the same time interval.

RESULTS

Of 1,132,844 autologous ART cycles 335,462 resulted in a live birth (29.6%). An additional, 217,030 3ART cycles resulted in 86,063 live births (39.7%). Hispanic and Black women demonstrated high fertility and lower utilization rates of autologous ART and 3ART. Caucasian and Asian women exhibited lower fertility rates and higher autologous ART and 3ART utilization. Autologous ART resulted in higher live birth rates among Caucasian and Hispanic women and lower rates among Asian and especially Black women. 3ART improved live birth rates in all races/ethnicities, though Black women experienced lower live birth rates with most modalities. Spontaneous abortion rates were higher among Black women following autologous ART and some 3ART modalities than those among Caucasian women.

CONCLUSION

Utilization of ART is inversely related to fertility rates. Autologous ART produces lower live birth rates among Asian and Black women. 3ART results in relatively low live birth rates among Black women.

TRIAL REGISTRATION

SART CORS #57 , Registered 5/14/2015.

Association of skewed X-chromosome inactivation with FMR1 CGG repeat length and anti-Mullerian hormone levels: a cohort study

BACKGROUND

Premutation range CGGn repeats of the FMR1 gene denote risk toward primary ovarian insufficiency (POI), also called premature ovarian failure (POF). This prospective cohort study was undertaken to determine if X-chromosome inactivation skew (sXCI) is associated with variations in FMR1 CGG repeat length and, if so, is also associated with age adjusted antimüllerian hormone (AMH) levels as an indicator of functional ovarian reserve (FOR).

METHODS

DNA samples of 58 women were analyzed for methylation status and confirmation of CGG_n repeat length. Based on previously described FMR1 genotypes, there were 18 women with norm FMR1 (both alleles in range of CGG _n=26-34), and 40 women who had at least one allele at CGG_n<26 or CGG_{>34 (} not-norm FMR1). As part of a routine evaluation of ovarian reserve, patients at our fertility center have their serum AMH assessed at first visit. Regression models were used to test the association of ovarian reserve, as indicated by serum AMH, with sXCI.

RESULTS

sXCI was significantly lower among infertility patients with norm FMR1 (6.5 ± 11.1, median and IQR) compared to those with not-norm FMR1 (12.0 ± 14.6, P = 0.005), though among young oocyte donors the opposite effect was observed. Women age >30 to 38 years old demonstrated greater ovarian reserve in the presence of lower sXCI as evidenced by significantly higher AMH levels (GLM sXCI_10%, f = 11.27; P = 0.004).

CONCLUSIONS

Together these findings suggest that FMR1 CGG repeat length may have a role in determining X-chromosome inactivation which could represent a possible mechanism for previously observed association of low age adjusted ovarian reserve with FMR1 variations in repeat length. Further, larger, investigations will be required to test this hypothesis.

The impact of FMR1 gene mutations on human reproduction and development: a systematic review

PURPOSE

This is a comprehensive review of the literature in this field attempting to put the FMR1 gene and its evaluation into context, both in general and for the reproductive health audience.

METHODS

Online database search of publications with systematic review of all papers relevant to ovarian reserve and assisted reproduction was done.

RESULTS

Relevant papers were identified and assessed, and an attempt was made to understand, rationalize and explain the divergent views in this field of study. Seminal and original illustrations were employed.

CONCLUSIONS

FMR1 is a highly conserved gene whose interpretation and effect on outcomes remains controversial in the reproductive health setting. Recent re-evaluations of the commonly accepted normal range have yielded interesting tools for possibly explaining unexpected outcomes in assisted reproduction. Fragile X investigations should perhaps become more routinely assessed in the reproductive health setting, particularly following a failed treatment cycle where oocyte quality is thought to be a contributing factor, or in the presence of a surprise finding of diminished ovarian reserve in a young patient.

Correlation of normal-range FMR1 repeat length or genotypes and reproductive parameters

PURPOSE

This study aims to ascertain whether the length of normal-ranged CGG repeats on the FMR1 gene correlates with abnormal reproductive parameters.

METHODS

We performed a retrospective, cross-sectional study of all FMR1 carrier screening performed as part of routine care at a large university-based fertility center from January 2011 to March 2014. Correlations were performed between normal-range FMR1 length and baseline serum anti-Müllerian hormone (AMH), cycle day 3 follicle stimulating hormone (FSH), ovarian volumes (OV), antral follicle counts (AFC), and incidence of diminished ovarian reserve (DOR), while controlling for the effect of age.

RESULTS

Six hundred three FMR1 screening results were collected. One subject was found to be a pre-mutation carrier and was excluded from the study. Baseline serum AMH, cycle day 3 FSH, OV, and AFC data were collected for the 602 subjects with normal-ranged CGG repeats. No significant difference in median age was noted amongst any of the FMR1 repeat genotypes. No significant correlation or association was found between any allele length or genotype, with any of the reproductive parameters or with incidence of DOR at any age (p > 0.05). However, subjects who were less than 35 years old with low/low genotype were significantly more likely to have below average AMH levels compared to those with normal/normal genotype (RR 3.82; 95 % CI 1.38-10.56).

CONCLUSIONS

This large study did not demonstrate any substantial association between normal-range FMR1 repeat lengths and reproductive parameters.

An Update on Ovarian Aging and Ovarian Reserve Tests

Ovaries are the female organs that age more quickly than other tissues such as the uterus, the pituitary gland or pancreas. Different from males, an interesting question is why and how the females lose fertility so rapidly. During the aging process, both the number and quality of the oocytes in the ovaries decrease and reach to a point beyond that no more viable offspring may be produced and the associated cyclic endocrinological activities cease, entering the menopause in females at an average age of 50 years. Females who delayed childbearing with or without their willing until their 30 years or 40 years constitute the largest portion of the total infertility population. Ovarian reserve tests (ORTs) provide an indirect estimate of a female’s diminishing ovarian reserve or remaining follicular pool. This article briefly reviews recent progresses in relation to ovarian aging and ORTs.

Early decline in functional ovarian reserve in young women with low (CGGn < 26) FMR1 gene alleles

Mouse fmr1 models, and recent cross-sectional human data, suggest that different triple CGGn ranges of the fragile X mental retardation 1 (FMR1) gene are associated with variations in ovarian aging and infertility treatment outcomes. The FMR1 mutation affecting reproductive function most negatively in humans is the so-called low mutation, characterized by CGGn < 26. We here present a first longitudinal study of selected young women with normal functional ovarian reserve (FOR). In a prospective cohort study, we selected among 233 young oocyte donors (mean age 24.8 ± 3.3 years) as study population of 66 who had more than 1 anti-Müllerian hormone (AMH) level drawn over a 4-year period. AMH curves, as reflection of FOR, were then statistically compared between women with and without low FMR1 alleles. Biallelic low FMR1 (hom-low/low) donors already at initial presentation demonstrated significantly lower FOR than donors with biallelic normal (norm) FMR1 (CGGn = 26-34; P = 0.001). Although monoallelic low FMR1 at initial presentation was not yet associated with decreased FOR, it over 4 years did demonstrate significantly enhanced declines in FOR (P = 0.046). Including repeat measurements, low/low (P = 0.006) and high/high (CGGn > 34) alleles (P < 0.001) demonstrated lower FOR by AMH than norm donors. Even monoallelic low FMR1 alleles are, thus, already at young female ages associated with accelerated declines in FOR. Low FMR1 alleles, therefore, potentially represent a screening tool for women at genetic risk toward premature ovarian senescence, representing in all races circa 10% of the female population.

Deregulation of key signaling pathways involved in oocyte maturation in FMR1 premutation carriers with Fragile X-associated primary ovarian insufficiency

FMR1 premutation female carriers are at risk for Fragile X-associated primary ovarian insufficiency (FXPOI). Insights from knock-in mouse model have recently demonstrated that FXPOI is due to an increased rate of follicle depletion or an impaired development of the growing follicles. Molecular mechanisms responsible for this reduced viability are still unknown. In an attempt to provide new data on the mechanisms that lead to FXPOI, we report the first investigation involving transcription profiling of total blood from FMR1 premutation female carriers with and without FXPOI. A total of 16 unrelated female individuals (6 FMR1 premutated females with FXPOI; 6 FMR1 premutated females without FXPOI; and 4 no-FXPOI females) were studied by whole human genome oligonucleotide microarray (Agilent Technologies). Fold change analysis did not show any genes with significant differential gene expression. However, functional profiling by gene set analysis showed large number of statistically significant deregulated GO annotations as well as numerous KEGG pathways in FXPOI females. These results suggest that the impairment of fertility in these females might be due to a generalized deregulation of key signaling pathways involved in oocyte maturation. In particular, the vasoendotelial growth factor signaling, the inositol phosphate metabolism, the cell cycle, and the MAPK signaling pathways were found to be down-regulated in FXPOI females. Furthermore, a high statistical enrichment of biological processes involved in cell death and survival were found deregulated among FXPOI females. Our results provide new strategic approaches to further investigate the molecular mechanisms and potential therapeutic targets for FXPOI not focused in a single gene but rather in the set of genes involved in these pathways.

Maximizing the clinical utility of antimüllerian hormone testing in women's health

Purpose of review

To provide an update on the latest clinical applications of serum antimüllerian hormone (AMH) testing with practical approaches to mitigate the impact of significant variability in AMH results.

Recent findings

Recent studies continue to demonstrate that AMH is the best single serum test for ovarian response management with, at most, a weak-to-moderate age-independent association with live-birth rate and time to conception. Data confirm serum AMH levels improve menopause prediction, monitoring of ovarian damage, and identification of women at risk for several ovary-related disorders such as polycystic ovary syndrome and premature or primary ovarian insufficiency. However, it is now recognized that serum AMH results can have dramatic variability due to common, biologic fluctuations within some individuals, use of hormonal contraceptives or other medications, certain surgical procedures, specimen treatment, assay changes, and laboratory calibration differences. Practical guidelines are provided to minimize the impact of variability in AMH results and maximize the accuracy of clinical decision-making.

Summary

AMH is an ovarian biomarker of central importance which improves the clinical management of women's health. However, with the simultaneous rapid expansion of AMH clinical applications and recognition of variability in AMH results, consensus regarding the clinical cutpoints is increasingly difficult. Therefore, a careful approach to AMH measurement and interpretation in clinical care is essential.

How the FMR1 gene became relevant to female fertility and reproductive medicine

This manuscript describes the 6 year evolution of our center’s research into ovarian functions of the FMR1 gene, which led to the identification of a new normal CGGn range of 26–34. This “new” normal range, in turn, led to definitions of different alleles (haplotypes) based on whether no, one or both alleles are within range. Specific alleles then were demonstrated to represent distinct ovarian aging patterns, suggesting an important FMR1 function in follicle recruitment and ovarian depletion of follicles. So called low alleles, characterized by CGGn_<26, appear associated with most significant negative effects on reproductive success. Those include occult primary ovarian insufficiency (OPOI), characterized by prematurely elevated follicle stimulating hormone (FSH) and prematurely low anti-Müllerian hormone, and significantly reduced clinical pregnancy rates in association with in vitro fertilization (IVF) in comparison to women with normal (norm) and high (CGGn_>34) alleles. Because low FMR1 alleles present in approximately 25% of all females, FMR1 testing at young ages may offer an opportunity for earlier diagnosis of OPOI than current practice allows. Earlier diagnosis of OPOI, in turn, would give young women the options of reassessing their reproductive schedules and/or pursue fertility preservation via oocyte cryopreservation when most effective.

FMR1 premutation is an uncommon explanation for premature ovarian failure in Han Chinese

BACKGROUND

In premature ovarian failure (POF), cessation of menstruation occurs before the expected age of menopause. Approximately 1% of women are affected. FMR1 premutation was reported to be responsible for up to 3.3%-6.7% of sporadic POF and 13% of familial cases in Caucasians, while the data was absent in Chinese population. Therefore, the impact of FMR1 CGG repeat on ovarian reserve is needed to be investigated in large Chinese cohort.

METHODS

The number of FMR1 CGG repeat was determined in 379 Han Chinese women with well-defined 46, XX non-syndromic sporadic POF and 402 controls. The age of menopause onset in respect to CGG repeats was further analyzed.

RESULTS

The frequency of FMR1 premutation in Han Chinese POF was only 0.5% (2/379), although it was higher than that in matched controls (0%, 0/402), it was much lower than that reported in Caucasian with POF (3.3%-6.7%). The prevalence of intermediate FMR1 (41-54) was not increased significantly in sporadic POF than that in controls (2.9% vs. 1.7%, P = 0.343). However, POF patients more often carried a single additional CGG repeat in a single allele than did fertile women (allele-1: 29.7 vs. 28.8, P<0.001; allele-2: 32.6 vs. 31.5, P < 0.001). POF patients with both alleles of CGG repeats outside (below or above) the normal range (26-34) showed an earlier age of cessation of menses than those with two alleles within normal range (hom-high/high vs. norm: 20.4 ± 4.8 vs. 24.7 ± 6.4, p < 0.01; hom-low/high vs. norm: 18.7 ± 1.7 vs. 24.7 ± 6.4, p < 0.01).

CONCLUSIONS

FMR1 premutation seems to be an uncommon explanation for POF in Han Chinese. However, having both alleles with CGG repeats outside the normal range might still adversely affect ovarian aging.

Utilizing FMR1 gene mutations as predictors of treatment success in human in vitro fertilization

CONTEXT

Mutations of the fragile X mental retardation 1 (FMR1) gene are associated with distinct ovarian aging patterns.

OBJECTIVE

To confirm in human in vitro fertilization (IVF) that FMR1 affects outcomes, and to determine whether this reflects differences in ovarian aging between FMR1 mutations, egg/embryo quality or an effect on implantation.

DESIGN, SETTING, PATIENTS

IVF outcomes were investigated in a private infertility center in reference to patients' FMR1 mutations based on a normal range of CGG(n = 26-34) and sub-genotypes high (CGG(n>34)) and low (CGG(<26)). The study included 3 distinct sections and study populations: (i) A generalized mixed-effects model of morphology (777 embryos, 168 IVF cycles, 125 infertile women at all ages) investigated whether embryo quality is associated with FMR1; (ii) 1041 embryos in 149 IVF cycles in presumed fertile women assessed whether the FMR1 gene is associated with aneuploidy; (iii) 352 infertile patients (< age 38; in 1st IVF cycles) and 179 donor-recipient cycles, assessed whether the FMR1 gene affects IVF pregnancy chances via oocyte/embryo quality or non-oocyte maternal factors.

INTERVENTIONS

Standardized IVF protocols.

MAIN OUTCOME MEASURES

Morphologic embryo quality, ploidy and pregnancy rates.

RESULTS

(i) Embryo morphology was reduced in presence of a low FMR1 allele (P = 0.032). In absence of a low allele, the odds ratio (OR) of chance of good (vs. fair/poor) embryos was 1.637. (ii) FMR1 was not associated with aneuploidy, though aneuploidy increased with female age. (iii) Recipient pregnancy rates were neither associated with donor age or donor FMR1. In absence of a low FMR1 allele, OR of clinical pregnancy (vs. chemical or no pregnancy) was 2.244 in middle-aged infertility patients.

CONCLUSIONS

A low FMR1 allele (CGG(<26)) is associated with significantly poorer morphologic embryo quality and pregnancy chance. As women age, low FMR1 alleles affect IVF pregnancy chances by reducing egg/embryo quality by mechanisms other than embryo aneuploidy.