Live birth rate is associated with oocyte yield and number of biopsied and suitable blastocysts to transfer in preimplantation genetic testing (PGT) cycles for monogenic disorders and chromosomal structural rearrangements

Embryo and fetal gene editing: Technical challenges and progress toward clinical applications

Gene modification therapies (GMTs) are slowly but steadily making progress toward clinical application. As the majority of rare diseases have an identified genetic cause, and as rare diseases collectively affect 5% of the global population, it is increasingly important to devise gene correction strategies to address the root causes of the most devastating of these diseases and to provide access to these novel therapies to the most affected populations. The main barriers to providing greater access to GMTs continue to be the prohibitive cost of developing these novel drugs at clinically relevant doses, subtherapeutic effects, and toxicity related to the specific agents or high doses required. In vivo strategy and treating younger patients at an earlier course of their disease could lower these barriers. Although currently regarded as niche specialties, prenatal and preconception GMTs offer a robust solution to some of these barriers. Indeed, treating either the fetus or embryo benefits from economy of scale, targeting pre-pathological tissues in the fetus prior to full pathogenesis, or increasing the likelihood of complete tissue targeting by correcting pluripotent embryonic cells. Here, we review advances in embryo and fetal GMTs and discuss requirements for clinical application.

A clinical predictive model for live birth in women of advanced age undergoing PGT cycles

PURPOSE

The trend of delaying childbirth has resulted in a growing number of advanced-aged women who are opting for preimplantation genetic testing (PGT) to screen for monogenic diseases or structural chromosomal rearrangements (PGT-M and PGT-SR). This increase in demand necessitates the development of a clinical predictive model for live birth outcomes in these women. Therefore, the objective of this study is to construct a comprehensive predictive model that assesses the likelihood of achieving a successful live birth in advanced-aged women undergoing PGT-M and PGT-SR treatments.

METHODS

A retrospective cohort study of 37-45-year-old women undergoing preimplantation genetic testing for monogenic disease or structural chromosomal rearrangement cycles from 2010 to 2021 was conducted at a university hospital reproductive centre. The purpose was to develop a clinical predictive model for live birth in these women. The main outcome studied was the cumulative live birth rate in the first or subsequent cycles. Developing a decision tree enabled a comprehensive study of clinical parameters and expected outcomes.

RESULTS

The analysis included 158 women undergoing 753 preimplantation genetic testing cycles. The cumulative live birth rate was 37.342% (59/158). Decision tree analysis revealed that women aged ≤ 40.1 or women > 40.1 with one or more top-quality transferable embryos in their first cycle had the best chance for a live baby (56% and 41%, respectively). Those older than 40.1 without top-quality embryos and seven or fewer dominant follicles had no live births. A Kaplan-Meier curve showed that for autosomal dominant diseases, there was a negligible increase in live birth rate after three cycles, compared to six cycles in autosomal recessive inheritance.

CONCLUSION

In older women, the chance of delivering after repeated cycles is higher in those with at least one top-quality unaffected embryo in their first preimplantation genetic testing cycle. Additional preimplantation genetic testing cycles after three in carriers of an autosomal dominant disorder and six in those with an autosomal recessive disorder should be considered prudently.

Is controlled ovarian stimulation safe in patients with hormone receptor-positive breast cancer receiving neoadjuvant chemotherapy?

INTRODUCTION

Controlled ovarian stimulation (COS) for oocyte/embryo cryopreservation is the method of choice for fertility preservation (FP) in young patients diagnosed with early-stage breast cancer (eBC). Nevertheless, some challenges still question its role, particularly in the neoadjuvant setting, where concerns arise about potential delay in the onset of anticancer treatment, and in hormone receptor-positive (HR+) disease, as cancer cells may proliferate under the estrogenic peak associated with stimulation. Therefore, this review aims to examine the available evidence on the safety of COS in eBC patients eligible for neoadjuvant treatment (NAT), particularly in HR+ disease.

METHODS

A comprehensive literature search was conducted to identify studies evaluating the feasibility and safety of COS in eBC and including patients referred to NAT and/or with HR+ disease. Time to NAT and survival outcomes were assessed.

RESULTS

Of the three matched cohort studies assessing the impact of COS on time to start NAT, only one reported a significant small delay in the cohort undergoing COS compared with the control group, whereas the other studies found no difference. Regarding survival outcomes, overall, no increased risk of recurrence or death was found, either in patients undergoing COS in the neoadjuvant setting regardless of HR expression or in HR+ disease regardless of the timing of COS relative to surgery. However, there are no data on the safety of COS in the specific combined scenario of HR+ disease undergoing NAT.

CONCLUSION

Neither the indication to NAT nor the HR positivity constitutes per se an a priori contraindication to COS. Shared decision making between clinicians and patients is essential to carefully weigh the risks and benefits in each individual case. Prospective studies designed to specifically investigate this issue are warranted.

Fertility Preservation as an Option for Women with Genetic Disorders: Insights from a SWOT Analysis on Elective Oocyte Freezing and Preimplantation Genetic Testing

This paper uses a SWOT (strengths, weaknesses, opportunities, and threats) analysis to overview the option of fertility preservation in women with genetic diseases, who would later use preimplantation genetic testing for monogenic disorders, in order to not transmit their condition. Strengths associated with elective oocyte freezing are ethical considerations, overall maternal and fetal safety, and effectiveness, if performed at <35 years of age. Weaknesses are related to costs and rare but present (<1-3%) risks of maternal complications. Counselling on fertility management aimed at preventing infertility offers a valuable opportunity, the same as it has been in oncological patients' care. The potentially high percentage of women with genetic conditions who would return to use their frozen oocytes also represents an opportunity together with the minimization of the need for egg donation, which has higher obstetrical risks compared to the use of autologous oocytes. Finally, a threat is represented by the potential psychological distress to young women who could never attempt to become pregnant through preimplantation genetic testing, or do it before any decline in their fertility. Potential unknown future long-term health risks for children conceived after egg vitrification/thawing are also a threat, but current knowledge is reassuring. Altogether, early counselling on the option of fertility preservation should thus be incorporated into standard care of all patients with any genetic condition.

Knowledge, acceptability and personal attitude toward pre-implantation 1 genetic testing (PGT) and pre-natal diagnosis (PND) for females carrying BRCA pathogenic variant according to fertility preservation experience

PURPOSE

Preimplantation genetic testing (PGT-M) and prenatal diagnosis (PND) followed by medical termination of pregnancy when the fetus is affected are two procedures developed to avoid the transmission of a severe hereditary disease which can be proposed to females that carried BRCA pathogenic variants. These females can also be offered fertility preservation (FP) when diagnosed with cancer or even before a malignancy occurs. The aim of the study was to evaluate the acceptability and personal attitude of women carrying a BRCA mutation toward techniques that can prevent BRCA transmission to their progeny.

METHODS

Female mutated for BRCA1 or BRCA2 were invited to complete an online survey of 49 queries anonymously between June and August 2022.

RESULTS

A total of 87 participants responded to the online survey. Overall, 86.2% of women considered that PGT-M should be proposed to all BRCA mutation carriers regardless of the severity of the family history, and 47.1% considered or would consider PGT-M for themselves. For PND, these percentages were lower reaching 66.7% and 29.9%, respectively. Females with personal history of breast cancer or FP achievement were more prone to undergo PND for themselves despite the overall acceptability of this procedure. Among the subgroup who had undergone FP (n = 58), there was no significant difference in acceptance of principle and personal attitude toward PGT-M and PND compared to the group without FP.

CONCLUSION

BRCA pathogenic variants female carriers do need information about reproductive issues, even if they are not prone to undergo PGT-M nor PND for themselves.

TRIAL REGISTRATION NUMBER

N/A.

Preimplantation genetic testing for hereditary hearing loss in Chinese population

PURPOSE

To evaluate the clinical validity of preimplantation genetic testing (PGT) to prevent hereditary hearing loss (HL) in Chinese population.

METHODS

A PGT procedure combining multiple annealing and looping-based amplification cycles (MALBAC) and single-nucleotide polymorphisms (SNPs) linkage analyses with a single low-depth next-generation sequencing run was implemented. Forty-three couples carried pathogenic variants in autosomal recessive non-syndromic HL genes, GJB2 and SLC26A4, and four couples carried pathogenic variants in rare HL genes: KCNQ4, PTPN11, PAX3, and USH2A were enrolled.

RESULTS

Fifty-four in vitro fertilization (IVF) cycles were implemented, 340 blastocysts were cultured, and 303 (89.1%) of these received a definite diagnosis of a disease-causing variant testing, linkage analysis and chromosome screening. A clinical pregnancy of 38 implanted was achieved, and 34 babies were born with normal hearing. The live birth rate was 61.1%.

CONCLUSIONS AND RELEVANCE

In both the HL population and in hearing individuals at risk of giving birth to offspring with HL in China, there is a practical need for PGT. The whole genome amplification combined with NGS can simplify the PGT process, and the efficiency of PGT process can be improved by establishing a universal SNP bank of common disease-causing gene in particular regions and nationalities. This PGT procedure was demonstrated to be effective and lead to satisfactory clinical outcomes.

Should Preimplantation Genetic Testing (PGT) Systematically Be Proposed to BRCA Pathogenic Variant Carriers?

Over the past years, BRCA genes pathogenic variants have been associated to reproductive issues. Indeed, evidence indicate that BRCA-mutated patients are not only at higher risk of developing malignancies, but may also present a reduction of the follicular stockpile. Given these characteristics, BRCA patients may be candidates to fertility preservation (FP) techniques or preimplantation genetic testing (PGT) to avoid the transmission of this inherited situation. Since the success rates of both procedures are highly related to the number of oocytes that could be recovered after ovarian stimulation, predicted by ovarian reserve tests, they are ideally performed before the diagnosis of cancer and its treatment. Despite the specific reproductive challenges related to BRCA status, no international guidelines for the application of PGT and FP in this subgroup of patients is currently available. The present article aims to review the available data regarding BRCA carriers' ovarian reserve and PGT success rates in oncologic and non-oncologic contexts, to determine the actual indication of PGT and further to improve patients' care pathway.

Carrier screening and PGT for an autosomal recessive monogenic disorder: insights from virtual trials

PURPOSE

To assess the costs and benefits of carrier screening and preimplantation genetic testing (PGT) for recessive autosomal monogenic disorders for couples attempting assisted conception.

METHODS

A simulated first full cycle for women less than 35 years transferring embryos one at a time. The effect of testing on pregnancy outcomes was evaluated for different reporting scenarios. A Monte Carlo method utilising 1000 trials for 10,000 couples, testing 4, 16 and 38 genes, was used to assess the numbers likely to be at high risk and to estimate the incremental cost of screening and PGT to avoid an affected child.

RESULTS

PGT for high-risk couples: testing embryos only for the monogenic condition avoided 1 affected pregnancy for 4 cycles started. Combined with testing for chromosomal aneuploidy: ranking test results avoided 1 adverse pregnancy (affected, biochemical, clinical miscarriage) from 3 cycles started; 1 in 2 when excluding from transfer all embryos with an abnormal test result, within 1 in 25 fewer women achieving an unaffected live birth. Carrier screening for 4, 16 and 38 gene scenarios, where 1:250, 1:196 and 1:29 couples were at high risk: the incremental cost to prevent 1 affected live birth was estimated to be less than GBP 1,150,000 (US $1,587,000), < 836,642 (1,154,566) and < 137,794 (190,156), respectively, in 95% of trials.

CONCLUSIONS

Carrier screening combined with PGT, with and without testing for unrelated chromosomal abnormalities, for couples attempting assisted conception is complex but likely to be effective and also expensive.

Ethical considerations of preconception and prenatal gene modification in the embryo and fetus

The National Academies of Sciences and Medicine 2020 consensus statement advocates the reinstatement of research in preconception heritable human genome editing (HHGE), despite the ethical concerns that have been voiced about interventions in the germline, and outlines criteria for its eventual clinical application to address monogenic disorders. However, the statement does not give adequate consideration to alternative technologies. Importantly, it omits comparison to fetal gene therapy (FGT), which involves gene modification applied prenatally to the developing fetus and which is better researched and less ethically contentious. While both technologies are applicable to the same monogenic diseases causing significant prenatal or early childhood morbidity, the benefits and risks of HHGE are distinct from FGT though there are important overlaps. FGT has the current advantage of a wealth of robust preclinical data, while HHGE is nascent technology and its feasibility for specific diseases still requires scientific proof. The ethical concerns surrounding each are unique and deserving of further discussion, as there are compelling arguments supporting research and eventual clinical translation of both technologies. In this Opinion, we consider HHGE and FGT through technical and ethical lenses, applying common ethical principles to provide a sense of their feasibility and acceptability. Currently, FGT is in a more advanced position for clinical translation and may be less ethically contentious than HHGE, so it deserves to be considered as an alternative therapy in further discussions on HHGE implementation.

Analysis of parental contribution for aneuploidy detection (APCAD): a novel method to detect aneuploidy and mosaicism in preimplantation embryos

RESEARCH QUESTION

Can (mosaic) aneuploidy be reliably detected in preimplantation embryos after multiple displacement amplification and single nucleotide polymorphism detection, independent of haplotyping and copy number detection, with a new method 'analysis of parental contribution for aneuploidy detection' or 'APCAD'?

DESIGN

This method is based on the maternal contribution, a parameter that reflects the proportion of DNA that is of maternal origin for a given chromosome or chromosome segment. A maternal contribution deviating from 50% for autosomes is strongly indicative of a (mosaic) chromosomal anomaly. The method was optimized using cell mixtures with varying ratios of euploid and aneuploid (47,XY,+21) lymphocytes. Next, the maternal contribution was retrospectively measured for all chromosomes from 349 Karyomapping samples.

RESULTS

Retrospective analysis showed a skewed maternal contribution (<36.4 or >63.6%) in 57 out of 59 autosome meiotic trisomies and all autosome monosomies (n = 57), with values close to theoretical expectation. Thirty-two out of 7436 chromosomes, for which no anomalies had been observed with Karyomapping, showed a similarly skewed maternal contribution.

CONCLUSIONS

APCAD was used to measure the maternal contribution, which is an intuitive parameter independent of copy number detection. This method is useful for detecting copy number neutral anomalies and can confirm diagnosis of (mosaic) aneuploidy detected based on copy number. Mosaic and complete aneuploidy can be distinguished and the parent of origin for (mosaic) chromosome anomalies can be determined. Because of these benefits, the APCAD method has the potential to improve aneuploidy detection carried out by comprehensive preimplantation genetic testing methods.

What is the threshold of mature oocytes to obtain at least one healthy transferable cleavage-stage embryo after preimplantation genetic testing for fragile X syndrome?

STUDY QUESTION

What are the chances of obtaining a healthy transferable cleavage-stage embryo according to the number of mature oocytes in fragile X mental retardation 1 (FMR1)-mutated or premutated females undergoing preimplantation genetic testing (PGT)?

SUMMARY ANSWER

In our population, a cycle with seven or more mature oocytes has an 83% chance of obtaining one or more healthy embryos.

WHAT IS KNOWN ALREADY

PGT may be an option to achieve a pregnancy with a healthy baby for FMR1 mutation carriers. In addition, FMR1 premutation is associated with a higher risk of diminished ovarian reserve and premature ovarian failure. The number of metaphase II (MII) oocytes needed to allow the transfer of a healthy embryo following PGT has never been investigated.

STUDY DESIGN, SIZE, DURATION

The study is a monocentric retrospective observational study carried out from January 2006 to January 2020 that is associated with a case-control study and that analyzes 38 FMR1 mutation female carriers who are candidates for PGT; 16 carried the FMR1 premutation and 22 had the full FMR1 mutation.

PARTICIPANTS/MATERIALS, SETTING, METHODS

A total of 95 controlled ovarian stimulation (COS) cycles for PGT for fragile X syndrome were analyzed, 49 in premutated patients and 46 in fully mutated women. Only patients aged ≤38 years with anti-Müllerian hormone (AMH) >1 ng/ml and antral follicle count (AFC) >10 follicles were eligible for the PGT procedure. Each COS cycle of the FMR1-PGT group was matched with the COS cycles of partners of males carrying any type of translocation (ratio 1:3). Conditional logistic regression was performed to compare the COS outcomes. We then estimated the number of mature oocytes needed to obtain at least one healthy embryo after PGT using receiver operating characteristic curve analysis.

MAIN RESULTS AND THE ROLE OF CHANCE

Overall, in the FMR1-PGT group, the median number of retrieved and mature oocytes per cycle was 11 (interquartile range 7-15) and 9 (6-12), respectively. The COS outcomes of FMR1 premutation or full mutation female carriers were not altered compared with the matched COS cycles in partners of males carrying a balanced translocation in their karyotype. Among the 6 (4-10) Day 3 embryos obtained in the FMR1-PGT group, a median number of 3 (1-6) embryos were morphologically eligible for biopsy, leading to 1 (1-3) healthy embryo. A cutoff value of seven MII oocytes yielded a sensitivity of 82% and a specificity of 61% of having at least one healthy embryo, whereas a cutoff value of 10 MII oocytes led to a specificity of 85% and improved positive predictive value.

LIMITATIONS, REASONS FOR CAUTION

This study is retrospective, analyzing a limited number of cycles. Moreover, the patients who were included in a fresh PGT cycle were selected on ovarian reserve parameters and show high values in ovarian reserve tests. This information could influence our conclusion.

WIDER IMPLICATIONS OF THE FINDINGS

The results relate only to the target population of this study, with a correct ovarian reserve of AMH >1 and AFC >10. However, the information provided herein extends knowledge about the current state of COS for FMR1 mutation carriers in order to provide patients with proper counseling regarding the optimal number of oocytes needed to have a chance of transferring an unaffected embryo following PGT.

STUDY FUNDING/COMPETING INTEREST(S)

None.

TRIAL REGISTRATION NUMBER

N/A.

Parameters of poor prognosis in preimplantation genetic testing for monogenic disorders

STUDY QUESTION

What is the likelihood of success of a single cycle of preimplantation genetic testing for monogenic disorders (PGT-M), measured as the cumulative live birth rate (CLBR) and based on various patient demographics?

SUMMARY ANSWER

For all women aged ≤40 years, the CLBR was at least 10% when the number of oocytes was ≥7 (range 10-30%) or was at least 5% when the number of oocytes was ≥3 (range 5-17%).

WHAT IS KNOWN ALREADY

The number of oocytes is significantly associated with the number of embryos for genetic testing and the clinical outcome in PGT-M. Embryos diagnosed as affected or embryos that remain without diagnosis cannot be used for embryo transfer. The size of the group of embryos non-suitable for transfer varies between 25% and 81%, depending on the indication. Thus, PGT-M is more likely to be more severely impacted by suboptimal ovarian response, poor fertilization and suboptimal embryo development than conventional IVF/ICSI schemes without PGT.

STUDY DESIGN, SIZE, DURATION

This was a single-centre retrospective comparative cohort study, of cycles between January 2011 and December 2015. A total number of 2265 PGT-M cycles were compared to 2833 conventional ICSI cycles. The principal aim of our study was the identification of the parameters of poor CLBR in couples undergoing PGT-M using multiplex short tandem repeat (STR) markers on blastomere biopsy DNA. The secondary aim was to compare the parameters of poor CLBR of the PGT-M population to those of couples undergoing ICSI without PGT.

PARTICIPANTS/MATERIALS, SETTING, METHODS

The baseline characteristics of the PGT-M group were compared to the conventional ICSI group. A multiple regression analysis was applied to account for the following potential confounding factors: female age, number of previous ART cycles, number of oocytes/suitable embryos for transfer and dosage of gonadotrophins used for ovarian stimulation.

MAIN RESULTS AND THE ROLE OF CHANCE

The PGT-M group was younger (female age 32.0 vs 34.5 years), had a higher number of previous ART cycles (1.1 vs 0.9 cycles) and used more gonadotrophins (2367 vs 1984 IU). Per cycle, the PGT-M group had more retrieved oocytes (11.8 vs 8.3 oocytes), fewer suitable embryos for transfer (1.7 vs 2.8 embryos) and a lower CLBR (29.4% vs 35.0%). Multiple regression analysis showed that the CLBR in the PGT-M group was significantly influenced by female age, the number of previous ART cycles, the number of oocytes and the dose of ovarian stimulation. In both groups, the predicted CLBR increased with increasing numbers of oocytes and suitable embryos. At least two retrieved oocytes or one embryo per single PGT-M cycle could confer an estimated CLBR above 10%. By assessing female age and the number of retrieved oocytes together, it was shown that for all women aged ≤40 years, the predicted CLBR per single PGT-M cycle was ≥10% when the number of oocytes was ≥7 or was ≥5% when the number of oocytes was ≥3.

LIMITATIONS, REASONS FOR CAUTION

Despite the large sample size, the findings are confined by limited confounder adjustment and the lack of specific PGT-M comparators.

WIDER IMPLICATIONS OF THE FINDINGS

This study aimed to describe the likelihood of success of PGT-M treatment, measured as CLBR, based on various patient demographics. In a PGT-M program, couples need to be informed of the prognosis more specifically when it is futile. The table of predicted CLBRs presented in this study is a useful tool in counselling PGT-M couples for making reproductive choices.

STUDY FUNDING/COMPETING INTEREST(S)

No funding was required and there are no competing interests.

TRIAL REGISTRATION NUMBER

N/A.

The usefulness of metaphase I oocytes in women who undergo controlled ovarian hyperstimulation for intracytoplasmic sperm injection

Objective:

The aim of this study was to evaluate the fertilization and blastocyst formation rates of oocytes in metaphase I (MI) obtained from women who underwent controlled ovarian hyperstimulation (COH) for intracytoplasmic injection.

Methods:

A prospective cohort study that included women from whom at least 1 MI and 1 MII oocyte were obtained after COH was performed. We collected 1,907 oocytes from 164 women (1291 MII, 352 MI and 258 prophase I or atretic). After oocyte classification, the MII and MI oocytes were incubated for 4 hours.

Results:

After 4 hours, the rescue maturation rate was 57.2%; 205 MI oocytes matured to MII oocytes in vitro (rescued MI-MII group), and 153 remained in MI (arrested MI group). The normal fertilization rates were directly associated with oocyte maturation, with rates of 79.1%, 60.2%, and 31.9% in MII, MI-MII and MI oocytes, respectively (p<0.001). Group arrested MI had an odds ratio (OR) of 7.6 (CI 5.2 - 11.2, p<0.001) for abnormal fertilization compared with Group MII. The blastocyst formation rate was directly associated with oocyte maturation, at 36.4% for MII, 11.4% for MI-MII and 0.6% for MI.

Conclusion:

Oocytes collected at the MI stage after OCH that did not mature to MII after rescue maturation had a blastocyst formation rate of only 0.6%, while those in MII and MI-MII had rates of 36.4% and 11.4%, respectively. However, we found a pregnancy with the birth of a healthy baby from a blastocyst formed after intracytoplasmic sperm injection (ICSI) of an MI oocyte.

Preimplantation genetic testing for carriers of BRCA1/2 pathogenic variants

The detection of germline BRCA1/2 pathogenic variant has relevant implications for the patients and their family members. Family planning, prophylactic surgery and the possibility of preimplantation genetic testing for monogenic disorders (PGT-M) to avoid transmittance of pathogenic variants to the offspring are relevant topics in this setting. PGT-M is valuable option for BRCA carriers, but it remains a controversial and underdiscussed topic. Although the advances in PGT technologies have improved pregnancy rate, there are still several important challenges associated with its use. The purpose of this review is to report the current evidence on PGT-M for BRCA1/2 carriers, ethical concerns and controversy associated with its use, reproductive implications of BRCA pathogenic variants, underlying areas in which an educational effort would be beneficial as well as possibilities for future research efforts in the field.

Are ovarian response and pregnancy rates similar in selected FMR1 premutated and mutated patients undergoing preimplantation genetic testing?

PURPOSE

To assess if the ovarian response of FMR1 premutated women undergoing preimplantation genetic testing (PGT) for Fragile X syndrome is lower compared with fully mutated patients, due to their frequent premature ovarian failure.

METHODS

In a retrospective cohort study from January 2009 to March 2019, we compared PGT outcomes in 18 FMR1 premutated women and 12 fully mutated women and aimed to identify predictive factors of stimulation outcomes.

RESULTS

Eighty-six IVF/PGT-M cycles for FMR1 PGT were analyzed. Premutation and full mutation patients were comparable in terms of age, body mass index (BMI), basal FSH, antral follicular count, and cycle length. However, premutation carriers had significantly lower AMH (1.9 versus 4.0 ng/mL, p = 0.0167). Premutated patients required higher doses of FSH (2740 versus 1944 IU, p = 0.0069) but had similar numbers of metaphase II oocytes (7.1 versus 6.6, p = 0.871) and embryos (5.6 versus 4.9, p = 0. 554). Pregnancy rates (37.1% versus 13.3%, p = 0.1076) were not statistically different in both groups.

CONCLUSION

In spite of lower ovarian reserve and thanks to an increased total dose of FSH, FMR1 premutated selected patients seem to have similar ovarian response as fully mutated patients. Neither the number of CGG repeats in FMR1 gene nor FMR1 mutation status was good predictors of the number of retrieved oocytes.