Evidence for Three Subgroups of Female FMR1 Premutation Carriers Defined by Distinct Neuropsychiatric Features: A Pilot Study

Over 200 Cytosine-guanine-guanine (CGG) trinucleotide repeats in the 5′ untranslated region of the Fragile X mental retardation 1 (FMR1) gene results in a “full mutation,” clinically Fragile X Syndrome (FXS), whereas 55 – 200 repeats result in a “premutation.” FMR1 premutation carriers (PMC) are at an increased risk for a range of psychiatric, neurocognitive, and physical conditions. Few studies have examined the variable expression of neuropsychiatric features in female PMCs, and whether heterogeneous presentation among female PMCs may reflect differential presentation of features in unique subgroups. In the current pilot study, we examined 41 female PMCs (ages 17–78 years) and 15 age-, sex-, and IQ-matched typically developing controls (TDC) across a battery of self-report, eye tracking, expressive language, neurocognitive, and resting state EEG measures to determine the feasibility of identifying discrete clusters. Secondly, we sought to identify the key features that distinguished these clusters of female PMCs. We found a three cluster solution using k-means clustering. Cluster 1 represented a psychiatric feature group (27% of our sample); cluster 2 represented a group with executive dysfunction and elevated high frequency neural oscillatory activity (32%); and cluster 3 represented a relatively unaffected group (41%). Our findings indicate the feasibility of using a data-driven approach to identify naturally occurring clusters in female PMCs using a multi-method assessment battery. CGG repeat count and its association with neuropsychiatric features differ across clusters. Together, our findings provide important insight into potential diverging pathophysiological mechanisms and risk factors for each female PMC cluster, which may ultimately help provide novel and individualized targets for treatment options.

Delineating the Relationships Between Motor, Cognitive-Executive and Psychiatric Symptoms in Female FMR1 Premutation Carriers

Introduction: Premutation expansions (55–200 CGG repeats) of the Fragile X Mental Retardation 1 (FMR1) gene on the X chromosome are associated with a range of clinical features. Apart from the most severe - Fragile X-Associated Tremor/Ataxia Syndrome (FXTAS) - where the most typical white matter changes affect cerebellar peduncles, more subtle changes may include impairment of executive functioning, affective disorders and/or subtle motor changes. Here we aimed to examine whether performance in selected components of executive functioning is associated with subclinical psychiatric symptoms in non-FXTAS, adult females carrying the FMR1 premutation.Methods and Sample: A total of 47 female premutation carriers (sub-symptomatic for FXTAS) of wide age range (26–77 years; M = 50.3; SD = 10.9) were assessed using standard neuropsychological tests, three motor rating scales and self-reported measures of psychiatric symptoms using the Symptom Checklist-90-Revised (SCL-90-R).Results: After adjusting for age and educational level where appropriate, both non-verbal reasoning and response inhibition as assessed on the Stroop task (i.e., the ability to resolve cognitive interference) were associated with a range of primary psychiatric symptom dimensions, and response inhibition uniquely predicted some primary symptoms and global psychiatric features. Importantly, lower scores (worse performance) in response inhibition were also strongly correlated with higher (worse) scores on standard motor rating scales for tremor-ataxia and for parkinsonism.Conclusion: These results provide evidence for the importance of response inhibition in the manifestation of psychiatric symptoms and subtle tremor-ataxia motor features, suggestive of the presence of early cerebellar changes in female premutation carriers.

Predictors of Comorbid Conditions in Women Who Carry an FMR1 Premutation

Purpose: Women who carry an FMR1 premutation (PM) can experience two well-established PM-associated disorders: fragile X-associated primary ovarian insufficiency (FXPOI, affects ~20–30% carriers) and fragile X-associated tremor-ataxia syndrome (FXTAS, affects ~6–15% carriers); however, emerging evidence indicates that some of these women experience complex health profiles beyond FXPOI and FXTAS.Methods: In an effort to better understand predictors for these comorbid conditions, we collected self-reported medical histories on 413 women who carry an FMR1 PM.Results: There were 22 health conditions reported by at least 9% of women. In an exploratory analysis, 12 variables were tested in logistic regression models for each comorbid condition, including demographic variables, environmental variables, PM-associated factors, and endorsement of depression and/or anxiety. More than half of the comorbid conditions studied were associated with women who self-reported having anxiety. Age, smoking, body mass index (BMI), and depression were also significant predictor variables for specific comorbid conditions.Conclusions: Age, smoking, and BMI were significantly associated with a subset of the comorbid conditions analyzed. Importantly, depression or anxiety were also significantly associated with many of the comorbid health conditions. This work highlights some of the modifiable factors associated with complex health profiles among women with an FMR1 PM.

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.

Men with FMR1 premutation alleles of less than 71 CGG repeats have low risk of being affected with fragile X-associated tremor/ataxia syndrome (FXTAS)

Fragile X-associated tremor/ataxia syndrome (FXTAS) is a late-onset condition characterised by cerebellar ataxia and intention tremor, usually found in individuals with FMR1 premutation alleles (PM—CGG expansion of 55–199 repeats). Population studies estimate that between 1 in 250 and 1 in 1600 men have a PM, with up to 45% of these men suggested to develop FXTAS by age 80. We used a Bayesian approach to compare the probability of finding a specific PM genotype in an ataxia population to a population control group and found an estimated penetrance of <1% (0.031%; CI 0.007% to 0.141%) for men with ≤70 CGGs. These findings suggest that men with a PM of ≤70 CGGs, who comprise the vast majority of those with a PM, have a much lower risk of being affected with FXTAS than previously suggested. This is an issue of growing importance for accurate genetic counselling, as those with a PM of ≤70 CGGs are increasingly detected through community carrier screening or neurodevelopmental assessment programmes.

Family as a Context for Child Development: Mothers with the FMR1 Premutation and Their Children with Fragile X Syndrome

Fragile X syndrome (FXS) is a genetic disorder caused by changes of the FMR1 gene that is passed along among families. A range of developmental processes may be impacted with wide variation in abilities across individuals with FXS. Mothers of children with FXS are often carriers of a “premutation” expansion on the FMR1 gene, which is associated with its own clinical phenotype. These maternal features may increase individual and family vulnerabilities, including increased risk for depression and anxiety disorders and difficulties in social and cognitive ability. These characteristics may worsen with age, and potentially interact with a child's challenging behaviors and with family dynamics. Thus, families of children with FXS may experience unique challenges related to genetic risk, manifested across both children and parents, that should be considered in therapeutic planning to optimize outcomes for children and their families. In this article, we review core features of the FMR1 premutation as expressed in mothers and aspects of the family environment that interface with developmental outcomes of children with FXS. Recommendations for family-centered support services are discussed.

Dysregulation of anti-Mullerian hormone expression levels in mural granulosa cells of FMR1 premutation carriers

FMR1 premutation (55–200 CGG repeats) results in fragile X-associated primary ovarian insufficiency (FXPOI). We evaluated expression levels of folliculogenesis-related mediators, follicle-stimulating hormone (FSH) receptor and anti-Mullerian hormone (AMH), to gain insights into the mechanisms underlying the reduced ovarian function. Mural granulosa cells (MGCs) were collected from FMR1 premutation carriers and noncarriers undergoing IVF treatments. At baseline, MGCs of carriers demonstrated significantly higher mRNA expression levels of AMH (3.5 ± 2.2, n = 12 and 0.97 ± 0.5, n = 17, respectively; p = 0.0003) and FSH receptor (5.6 ± 2.8 and 2.7 ± 2.8, respectively; p = 0.02) and higher AMH protein expression on immunostaining. Accordingly, FMR1 premutation-transfected COV434 cells exhibited higher AMH protein expression than COV434 cells transfected with 20 CGG repeats. We conclude that FMR1 premutation may lead to dysregulation of AMH expression levels, probably due to a compensatory mechanism. Elucidating the pathophysiology of FXPOI may help in early detection of ovarian dysfunction and tailoring IVF treatments to FMR1 premutation carriers.

P–514 RAN-Translation in Fragile X associated Premature Ovarian Insufficiency (FXPOI): FMRpolyG as a predictive tool

Study question Does repeat-associated non-AUG (RAN) translation lead to accumulation of polyglycine- containing protein (FMRpolyG) in human lymphocytes and mural granulosa cells of FMR1 premutation carriers? Summary answer Lymphocytes and granulosa cells from FMR1 premutation carriers contain intracellular inclusions that stain positive for both FMRpolyG and ubiquitin. What is known already: Fragile-X-associated-Primary-Ovarian-Insufficiency (FXPOI) is characterized by oligo/amenorrhea and hypergonadotropic hypogonadism associated with the expansion of CGG-repeats in the 5’UTR of FMR1, called premutation (PM) (n: 55–200). Approximately 20% of women carrying a FMR1-premutation (PM) allele develop FXPOI. RAN-translation dependent on variable CGG-repeat length is hypothesized to cause FXPOI due to the production of a polyglycine-containing FMR1-protein, FMRpolyG. Recently, FMRpolyG inclusions were found in neuronal brain cells of FXTAS patients and stromal cells of the ovary of an FXPOI patient. Study design, size, duration: Lymphocytes and granulosa cells (GCs) from women with PM (6) and women without PM (10) (controls) were analyzed by immunofluorescence (IF) staining for the presence of inclusions positive for ubiquitin and FMRpolyG. Cell lysis and protein extraction samples were subjected to Fluorescent Western Blot (WB) analysis to detect FMRP and FMRpolyG Participants/materials, setting, methods Human GCs were obtained from follicular fluid after oocyte retrieval and lymphocytes were isolated from peripheral blood using Ficoll-Paque. Cells suspended in PBS were adhered to a glass-coverslip placed at the bottom of the 6-well culture plate, via gravity sedimentation. Adhered cells were fixed, IF staining for FMRpolyG and ubiquitin was performed and analyzed by fluorescence microscopy. Fluorescent WB was used to demonstrate the expression of FMRP, FMRpolyG in extracted protein from lymphocytes and GCs. Main results and the role of chance FMRP was successfully detected by fluorescence WB in both lymphocytes and GCs. FMRP is mainly present in cytoplasm and was expressed in greater amount in GCs than in leukocytes. Moreover, FMRP expression was significantly decreased in GCs from FMR1-PM compared with controls. Lymphocytes from PM-carriers and controls were immunostained for FMRpolyG and ubiquitin. In PM-carriers, FMRpolyG was present as aggregates, whereas in controls only a weak signal without inclusions was detectable. The expression pattern of FMRpolyG in GCs was similar to that in lymphocytes with a significant increase in PM-carriers. There, the FMRpolyG-aggregates additionally demonstrated as ubiquitin-positive inclusions. These may resemble the toxic potential of these protein fractions involved the ovarian damage in developing FXPOI. Limitations, reasons for caution More patients are needed to support the present findings. Further investigation into the possible consequences of these FMRpolyG-positive inclusions in PM-carriers is also advisable. Wider implications of the findings: We found for the first time FMRpolyG-accumulation in lymphocytes and GCs from FMR1-PM-carriers in ubiquitin-positive inclusions. Future experiments evaluating consistency in more patients and elucidating the impact on fertility and prospective value for individual ovarian reserve are therefore in preparation. Trial registration number Not applicable