Understanding decreased fertility in women carriers of the FMR1 premutation: a possible mechanism for Fragile X-Associated Primary Ovarian Insufficiency (FXPOI)

Abstract 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

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Primary ovarian insufficiency in an adolescent population: clinical phenotype and diagnostic approach

Journal of Pediatric Endocrinology and Metabolism ◽

10.1515/jpem-2019-0083 ◽

2019 ◽

Vol 32 (9) ◽

pp. 979-985

Author(s):

Alfonso Hoyos-Martinez ◽

Luis R. Hoyos ◽

Metee Comkornruecha ◽

Alejandro Diaz

Keyword(s):

Clinical Phenotype ◽

Fragile X ◽

Clinical Information ◽

Rare Condition ◽

Primary Ovarian Insufficiency ◽

Diagnostic Approach ◽

Ovarian Insufficiency ◽

Adolescent Population ◽

Autoimmune Conditions ◽

Reproductive Counseling

Abstract Background Primary ovarian insufficiency (POI) can be seen in adolescents secondary to genetic or autoimmune conditions, or gonadotoxic therapies. Often times, its underlying cause is not identified. It is a rare condition in pediatrics, but a thorough evaluation is required for a timely diagnosis and optimizing outcomes. Objectives We aim to describe the clinical phenotype of idiopathic POI in an adolescent population seen in a referral center, and evaluate its diagnostic approach. Methods All patients evaluated between 2012 and 2018 were identified using the diagnostic codes for POI. Medical records were manually reviewed and clinical information was extracted. Cases were excluded from the final sample if they were found to have incomplete diagnostic information, Turner syndrome, eating disorders, gonadal surgeries and/or a history of oncological conditions or treatments. Results Forty-eight patients with POI were identified, and only seven met the established criteria. Anti-ovarian and anti-thyroid antibodies were evaluated in 100% and 86%, respectively, while only 29% were tested for anti-adrenal autoimmunity. The karyotype was obtained consistently, while the fragile X mental retardation 1 (FMR1) gene expansion was only assessed in approximately a third of the patients. Finally, only 29% of patients received reproductive counseling or referral to a fertility specialist. Conclusions Diagnostic evaluation for POI appears to be challenging to pediatric providers. Anti-ovarian antibodies are frequently obtained despite the lack of their clinical significance in POI, while anti-adrenal antibodies, which are the preferred diagnostic test, are not commonly obtained. Reproductive orientation or referral is seldom provided to the adolescent population.

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