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Mueller S, Decker L, Menge S, Ludolph AC, Freischmidt A. The Fragile X Protein Family in Amyotrophic Lateral Sclerosis. Mol Neurobiol 2023; 60:3898-3910. [PMID: 36991279 DOI: 10.1007/s12035-023-03330-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2022] [Accepted: 03/23/2023] [Indexed: 03/31/2023]
Abstract
The fragile X protein (FXP) family comprises the multifunctional RNA-binding proteins FMR1, FXR1, and FXR2 that play an important role in RNA metabolism and regulation of translation, but also in DNA damage and cellular stress responses, mitochondrial organization, and more. FMR1 is well known for its implication in neurodevelopmental diseases. Recent evidence suggests substantial contribution of this protein family to amyotrophic lateral sclerosis (ALS) pathogenesis. ALS is a highly heterogeneous neurodegenerative disease with multiple genetic and unclear environmental causes and very limited treatment options. The loss of motoneurons in ALS is still poorly understood, especially because pathogenic mechanisms are often restricted to patients with mutations in specific causative genes. Identification of converging disease mechanisms evident in most patients and suitable for therapeutic intervention is therefore of high importance. Recently, deregulation of the FXPs has been linked to pathogenic processes in different types of ALS. Strikingly, in many cases, available data points towards loss of expression and/or function of the FXPs early in the disease, or even at the presymptomatic state. In this review, we briefly introduce the FXPs and summarize available data about these proteins in ALS. This includes their relation to TDP-43, FUS, and ALS-related miRNAs, as well as their possible contribution to pathogenic protein aggregation and defective RNA editing. Furthermore, open questions that need to be addressed before definitively judging suitability of these proteins as novel therapeutic targets are discussed.
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Affiliation(s)
- Sarah Mueller
- Department of Neurology, Ulm University, Albert-Einstein-Allee 11, 89081, Ulm, Germany
| | - Lorena Decker
- Department of Neurology, Ulm University, Albert-Einstein-Allee 11, 89081, Ulm, Germany
| | - Sonja Menge
- Department of Neurology, Ulm University, Albert-Einstein-Allee 11, 89081, Ulm, Germany
| | - Albert C Ludolph
- Department of Neurology, Ulm University, Albert-Einstein-Allee 11, 89081, Ulm, Germany
- German Center For Neurodegenerative Diseases (DZNE) Ulm, Ulm, Germany
| | - Axel Freischmidt
- Department of Neurology, Ulm University, Albert-Einstein-Allee 11, 89081, Ulm, Germany.
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Van Der Kelen A, Okutman Ö, Javey E, Serdarogullari M, Janssens C, Ghosh MS, Dequeker BJH, Perold F, Kastner C, Kieffer E, Segers I, Gheldof A, Hes FJ, Sermon K, Verpoest W, Viville S. A systematic review and evidence assessment of monogenic gene-disease relationships in human female infertility and differences in sex development. Hum Reprod Update 2023; 29:218-232. [PMID: 36571510 DOI: 10.1093/humupd/dmac044] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Revised: 12/05/2022] [Indexed: 12/27/2022] Open
Abstract
BACKGROUND As in other domains of medicine, high-throughput sequencing methods have led to the identification of an ever-increasing number of gene variants in the fields of both male and female infertility. The increasing number of recently identified genes allows an accurate diagnosis for previously idiopathic cases of female infertility and more appropriate patient care. However, robust evidence of the gene-disease relationships (GDR) allowing the proper translation to clinical application is still missing in many cases. OBJECTIVE AND RATIONALE An evidence-based curation of currently identified genes involved in female infertility and differences in sex development (DSD) would significantly improve both diagnostic performance and genetic research. We therefore performed a systematic review to summarize current knowledge and assess the available GDR. SEARCH METHODS PRISMA guidelines were applied to curate all available information from PubMed and Web of Science on genetics of human female infertility and DSD leading to infertility, from 1 January 1988 to 1 November 2021. The reviewed pathologies include non-syndromic as well as syndromic female infertility, and endocrine and reproductive system disorders. The evidence that an identified phenotype is caused by pathogenic variants in a specific gene was assessed according to a standardized scoring system. A final score (no evidence, limited, moderate, strong, or definitive) was assigned to every GDR. OUTCOMES A total of 45 271 publications were identified and screened for inclusion of which 1078 were selected for gene and variant extraction. We have identified 395 genes and validated 466 GDRs covering all reported monogenic causes of female infertility and DSD. Furthermore, we present a genetic diagnostic flowchart including 105 genes with at least moderate evidence for female infertility and suggest recommendations for future research. The study did not take into account associated genetic risk factor(s) or oligogenic/polygenic causes of female infertility. WIDER IMPLICATIONS We have comprehensively reviewed the existing research on the genetics of female infertility and DSD, which will enable the development of diagnostic panels using validated genes. Whole genome analysis is shifting from predominantly research to clinical application, increasing its diagnostic potential. These new diagnostic possibilities will not only decrease the number of idiopathic cases but will also render genetic counselling more effective for infertile patients and their families.
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Affiliation(s)
- Annelore Van Der Kelen
- Clinical Sciences, Research Group Reproduction and Genetics, Centre for Medical Genetics, Vrije Universiteit Brussel (VUB), Universitair Ziekenhuis Brussel (UZ Brussel), Brussels, Belgium
| | - Özlem Okutman
- Laboratoire de Génétique Médicale LGM, Institut de Génétique Médicale d'Alsace IGMA, INSERM UMR 1112, Université de Strasbourg, Strasbourg, France.,Laboratoire de Diagnostic Génétique, Unité de Génétique de l'infertilité (UF3472), Hôpitaux Universitaires de Strasbourg, Strasbourg, France
| | - Elodie Javey
- Laboratoires de Diagnostic Génétique, Hôpitaux Universitaires de Strasbourg, Strasbourg, France
| | - Münevver Serdarogullari
- Department of Histology and Embryology, Faculty of Medicine, Cyprus International University, Northern Cyprus via Mersin 10, Turkey
| | - Charlotte Janssens
- Research Group Reproduction and Genetics, Vrije Universiteit Brussel (VUB), Brussels, Belgium
| | - Manjusha S Ghosh
- Research Group Reproduction and Genetics, Vrije Universiteit Brussel (VUB), Brussels, Belgium
| | - Bart J H Dequeker
- Clinical Sciences, Research Group Reproduction and Genetics, Centre for Medical Genetics, Vrije Universiteit Brussel (VUB), Universitair Ziekenhuis Brussel (UZ Brussel), Brussels, Belgium
| | - Florence Perold
- Research Group Reproduction and Genetics, Vrije Universiteit Brussel (VUB), Brussels, Belgium
| | - Claire Kastner
- Institut de Génétique Médicale d'Alsace IGMA, Hôpitaux Universitaires de Strasbourg, Strasbourg, France
| | - Emmanuelle Kieffer
- Service de Génétique Médicale, Laboratoires de Diagnostic Génétique, Unité de Diagnostic Préimplantatoire (UF9327), Hôpitaux Universitaires de Strasbourg, Strasbourg, France
| | - Ingrid Segers
- Clinical Sciences, Research Group Reproduction and Genetics, Brussels IVF Centre for Reproductive Medicine, Vrije Universiteit Brussel (VUB), Universitair Ziekenhuis Brussel (UZ Brussel), Brussels, Belgium.,Research Group Follicle Biology Laboratory (FOBI), Vrije Universiteit Brussel (VUB), Brussels, Belgium
| | - Alexander Gheldof
- Clinical Sciences, Research Group Reproduction and Genetics, Centre for Medical Genetics, Vrije Universiteit Brussel (VUB), Universitair Ziekenhuis Brussel (UZ Brussel), Brussels, Belgium
| | - Frederik J Hes
- Clinical Sciences, Research Group Reproduction and Genetics, Centre for Medical Genetics, Vrije Universiteit Brussel (VUB), Universitair Ziekenhuis Brussel (UZ Brussel), Brussels, Belgium
| | - Karen Sermon
- Research Group Reproduction and Genetics, Vrije Universiteit Brussel (VUB), Brussels, Belgium
| | - Willem Verpoest
- Clinical Sciences, Research Group Reproduction and Genetics, Brussels IVF Centre for Reproductive Medicine, Vrije Universiteit Brussel (VUB), Universitair Ziekenhuis Brussel (UZ Brussel), Brussels, Belgium
| | - Stéphane Viville
- Laboratoire de Génétique Médicale LGM, Institut de Génétique Médicale d'Alsace IGMA, INSERM UMR 1112, Université de Strasbourg, Strasbourg, France.,Laboratoire de Diagnostic Génétique, Unité de Génétique de l'infertilité (UF3472), Hôpitaux Universitaires de Strasbourg, Strasbourg, France
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3
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Rosario R, Stewart HL, Choudhury NR, Michlewski G, Charlet‐Berguerand N, Anderson RA. Evidence for a fragile X messenger ribonucleoprotein 1 (FMR1) mRNA gain-of-function toxicity mechanism contributing to the pathogenesis of fragile X-associated premature ovarian insufficiency. FASEB J 2022; 36:e22612. [PMID: 36250920 PMCID: PMC9828574 DOI: 10.1096/fj.202200468rr] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2022] [Revised: 09/22/2022] [Accepted: 10/03/2022] [Indexed: 01/12/2023]
Abstract
Fragile X-associated premature ovarian insufficiency (FXPOI) is among a family of disorders caused by expansion of a CGG trinucleotide repeat sequence located in the 5' untranslated region (UTR) of the fragile X messenger ribonucleoprotein 1 (FMR1) gene on the X chromosome. Women with FXPOI have a depleted ovarian follicle population, resulting in amenorrhea, hypoestrogenism, and loss of fertility before the age of 40. FXPOI is caused by expansions of the CGG sequence to lengths between 55 and 200 repeats, known as a FMRI premutation, however the mechanism by which the premutation drives disease pathogenesis remains unclear. Two main hypotheses exist, which describe an mRNA toxic gain-of-function mechanism or a protein-based mechanism, where repeat-associated non-AUG (RAN) translation results in the production of an abnormal protein, called FMRpolyG. Here, we have developed an in vitro granulosa cell model of the FMR1 premutation by ectopically expressing CGG-repeat RNA and FMRpolyG protein. We show that expanded CGG-repeat RNA accumulated in intranuclear RNA structures, and these aggregates were able to cause significant granulosa cell death independent of FMRpolyG expression. Using an innovative RNA pulldown, mass spectrometry-based approach we have identified proteins that are specifically sequestered by CGG RNA aggregates in granulosa cells in vitro, and thus may be deregulated as consequence of this interaction. Furthermore, we have demonstrated reduced expression of three proteins identified via our RNA pulldown (FUS, PA2G4 and TRA2β) in ovarian follicles in a FMR1 premutation mouse model. Collectively, these data provide evidence for the contribution of an mRNA gain-of-function mechanism to FXPOI disease biology.
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Affiliation(s)
- Roseanne Rosario
- MRC Centre for Reproductive Health, Queen's Medical Research InstituteUniversity of EdinburghEdinburghUK,Biomedical SciencesUniversity of EdinburghEdinburghUK
| | - Hazel L. Stewart
- MRC Centre for Reproductive Health, Queen's Medical Research InstituteUniversity of EdinburghEdinburghUK
| | | | - Gracjan Michlewski
- Infection MedicineUniversity of EdinburghEdinburghUK,Zhejiang University‐University of Edinburgh InstituteZhejiang UniversityZhejiangP.R. China,Dioscuri Centre for RNA‐Protein Interactions in Human Health and DiseaseInternational Institute of Molecular and Cell Biology in WarsawWarsawPoland
| | - Nicholas Charlet‐Berguerand
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC)INSERM U 1258, CNRS UMR 7104, Université of StrasbourgIllkirchFrance
| | - Richard A. Anderson
- MRC Centre for Reproductive Health, Queen's Medical Research InstituteUniversity of EdinburghEdinburghUK
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Sakka R, Abdelhedi F, Sellami H, Pichon B, Lajmi Y, Mnif M, Kebaili S, Derbel R, Kamoun H, Gdoura R, Delbaere A, Desir J, Abramowicz M, Vialard F, Dupont JM, Ammar-Keskes L. An unusual familial Xp22.12 microduplication including EIF1AX: A novel candidate dosage-sensitive gene for premature ovarian insufficiency. Eur J Med Genet 2022; 65:104613. [PMID: 36113757 DOI: 10.1016/j.ejmg.2022.104613] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Revised: 07/22/2022] [Accepted: 09/09/2022] [Indexed: 11/19/2022]
Abstract
We report on the results of array-CGH and Whole exome sequencing (WES) studies carried out in a Tunisian family with 46,XX premature ovarian insufficiency (POI). This study has led to the identification of a familial Xp22.12 tandem duplication with a size of 559.4 kb, encompassing only three OMIM genes (RPS6KA3, SH3KBP1and EIF1AX), and a new heterozygous variant in SPIDR gene: NM_001080394.3:c.1845_1853delTATAATTGA (p.Ile616_Asp618del) segregating with POI. Increased mRNA expression levels were detected for SH3KBP1 and EIF1AX, while a normal transcript level for RPS6KA3 was detected in the three affected family members, explaining the absence of intellectual disability (ID). To the best of our knowledge, this is the first duplication involving the Xp22.12 region, reported in a family without ID, but rather with secondary amenorrhea (SA) and female infertility. As EIF1AX is a regulatory gene escaping X-inactivation, which has an extreme dosage sensitivity and highly expressed in the ovary, we suggest that this gene might be a candidate gene for ovarian function. Homozygous nonsense pathogenic variants of SPIDR gene have been reported in familial cases in POI. It has been suggested that chromosomal instability associated with SPIDR molecular defects supports the role of SPIDR protein in double-stranded DNA damage repair in vivo in humans and its causal role in POI. In this family, the variant (p.Ile616_Asp618del), present in a heterozygous state, is located in the domain that interacts with BLM and might disrupt the BLM binding ability of SPIDR protein. These findings strengthen the hypothesis that the additional effect of this variant could lead to POI in this family. Although the work represents the first evidence that EIF1AX duplication might be responsible for POI through its over-expression, further functional studies are needed to clarify and prove EIF1AX involvement in POI phenotype.
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Affiliation(s)
- Rim Sakka
- Human Molecular Genetics Laboratory, Faculty of Medicine of Sfax, University of Sfax, Tunisia; Center of Medical Genetics, Erasme Hospital, Université Libre de Bruxelles, Brussels, Belgium
| | - Fatma Abdelhedi
- Human Molecular Genetics Laboratory, Faculty of Medicine of Sfax, University of Sfax, Tunisia; Medical Genetics Department, Hedi Chaker Hospital, Sfax, Tunisia.
| | - Hanen Sellami
- Water Researches and Technologies Center (CERTE), University of Carthage, Tourist Road Soliman, Nabeul, Tunisia; Toxicology, Environmental Microbiology and Health Research Laboratory (LR17ES06), Faculty of Sciences of Sfax, University of Sfax, Tunisia
| | - Bruno Pichon
- Center of Medical Genetics, Erasme Hospital, Université Libre de Bruxelles, Brussels, Belgium
| | - Yosra Lajmi
- Cytogenetics Department, Cochin Hospital, Assistance Publique des Hôpitaux de Paris, Sorbonne Paris Cité, Paris Descartes University, Medical School, Paris, France
| | - Mouna Mnif
- Department of Endocrinology, Hedi Chaker Hospital, Sfax, Tunisia
| | - Sahbi Kebaili
- Department of Gynecology, HediChaker Hospital, Sfax, Tunisia
| | - Rihab Derbel
- Human Molecular Genetics Laboratory, Faculty of Medicine of Sfax, University of Sfax, Tunisia
| | - Hassen Kamoun
- Medical Genetics Department, Hedi Chaker Hospital, Sfax, Tunisia
| | - Radhouane Gdoura
- Toxicology, Environmental Microbiology and Health Research Laboratory (LR17ES06), Faculty of Sciences of Sfax, University of Sfax, Tunisia
| | - Anne Delbaere
- Fertility Clinic, Department of Gynecology and Obstetrics, Erasme Hospital, UniversitéLibre de Bruxelles, Brussels, Belgium
| | - Julie Desir
- Center of Medical Genetics, Erasme Hospital, Université Libre de Bruxelles, Brussels, Belgium
| | - Marc Abramowicz
- Center of Medical Genetics, Erasme Hospital, Université Libre de Bruxelles, Brussels, Belgium
| | - François Vialard
- Genetics Department, CHI Poissy St Germain-en-Laye, F-78300, Poissy, France; RHuMA Team, UMR-BREED, INRAE-UVSQ-ENVA, UFR-SVS, F-78180, Montigny le Bretonneux, France
| | - Jean-Michel Dupont
- Cytogenetics Department, Cochin Hospital, Assistance Publique des Hôpitaux de Paris, Sorbonne Paris Cité, Paris Descartes University, Medical School, Paris, France
| | - Leila Ammar-Keskes
- Human Molecular Genetics Laboratory, Faculty of Medicine of Sfax, University of Sfax, Tunisia
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Gruber N, Haham LM, Raanani H, Cohen Y, Gabis L, Berkenstadt M, Ries-Levavi L, Elizur S, Pinhas-Hamiel O. Female fragile X premutation carriers are at increased risk for metabolic syndrome from early adulthood. Nutr Metab Cardiovasc Dis 2022; 32:1010-1018. [PMID: 35086765 DOI: 10.1016/j.numecd.2021.11.018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/15/2021] [Revised: 10/20/2021] [Accepted: 11/29/2021] [Indexed: 02/08/2023]
Abstract
BACKGROUND AND AIMS Women with primary ovarian insufficiency exhibit an unfavorable cardiovascular risk profile. A common cause for primary ovarian insufficiency is fragile X premutation (FXPC), and data on the cardiovascular risk factors in women with FXPC are scarce. We aimed to assess the prevalences of abnormal metabolic components among FXPC. METHODS AND RESULTS Clinical, anthropometric and laboratory data were collected from 71 women with FXPC and compared to 78 women referred for counseling in an in-vitro fertilization clinic (control group). The mean ± SD ages of the FXPC and control groups were 33.5 ± 5.6 and 36.2 ± 5.3 years, respectively (p = 0.003). In a logistic regression analysis, the FXPC group had increased risks for hyperglycemia, hypertriglyceridemia, central obesity and low high-density lipoprotein cholesterol, of 21.8-fold (95% CI 2.7-175, p = 0.004), 6.9-fold (95% CI 2.5-18.7, p < 0.0001), 3.1-fold (95% CI 1.4-6.9, p = 0.005) and 2.4-fold (95% CI 1.1-5.2, p = 0.03), compared to the control group. The FXPC group had 2.7-fold higher prevalence of two abnormal metabolic components; 19% met the full criteria of MetS, compared to 3% of the control group. Neither CGG repeats nor ovarian reserve markers were associated with metabolic risk. CONCLUSIONS Carriers of fragile X premutation are at increased metabolic risk from early adulthood; waist circumference, glucose and lipid levels are particularly elevated. We recommend metabolic screening for all women with FMR1 premutation, to enable early interventions for prevention of long-term cardiovascular comorbidities.
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Affiliation(s)
- Noah Gruber
- Pediatric Endocrine and Diabetes Unit, Edmond and Lily Safra Children's Hospital, Sheba Medical Center, Ramat Gan, Israel; Sackler School of Medicine, Tel-Aviv University, Tel Aviv, Israel.
| | | | - Hila Raanani
- Sackler School of Medicine, Tel-Aviv University, Tel Aviv, Israel; IVF Unit, Sheba Medical Center, Ramat Gan, Israel
| | - Yoram Cohen
- Sackler School of Medicine, Tel-Aviv University, Tel Aviv, Israel; IVF Unit, Sheba Medical Center, Ramat Gan, Israel
| | - LidiaV Gabis
- Sackler School of Medicine, Tel-Aviv University, Tel Aviv, Israel; Child Development Center, Edmond and Lily Safra Children's Hospital, Sheba Medical Center, Ramat Gan, Israel
| | - Michal Berkenstadt
- Sackler School of Medicine, Tel-Aviv University, Tel Aviv, Israel; The Danek Gertner Institute of Human Genetics, Sheba Medical Center, Ramat Gan, Israel
| | - Liat Ries-Levavi
- The Danek Gertner Institute of Human Genetics, Sheba Medical Center, Ramat Gan, Israel
| | - Shai Elizur
- Sackler School of Medicine, Tel-Aviv University, Tel Aviv, Israel; IVF Unit, Sheba Medical Center, Ramat Gan, Israel
| | - Orit Pinhas-Hamiel
- Pediatric Endocrine and Diabetes Unit, Edmond and Lily Safra Children's Hospital, Sheba Medical Center, Ramat Gan, Israel; Sackler School of Medicine, Tel-Aviv University, Tel Aviv, Israel
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Nguyen XP, Vilkaite A, Messmer B, Dietrich JE, Hinderhofer K, Schäkel K, Strowitzki T, Rehnitz J. Expression of FMRpolyG in Peripheral Blood Mononuclear Cells of Women with Fragile X Mental Retardation 1 Gene Premutation. Genes (Basel) 2022; 13:451. [PMID: 35328005 PMCID: PMC8951797 DOI: 10.3390/genes13030451] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2022] [Revised: 02/24/2022] [Accepted: 02/28/2022] [Indexed: 12/03/2022] Open
Abstract
Fragile X-associated primary ovarian insufficiency (FXPOI) is characterized by oligo/amenorrhea and hypergonadotropic hypogonadism and is caused by the expansion of the CGG repeat in the 5′UTR of Fragile X Mental Retardation 1 (FMR1). Approximately 20% of women carrying an FMR1 premutation (PM) allele (55–200 CGG repeat) develop FXPOI. Repeat Associated Non-AUG (RAN)-translation dependent on the variable CGG-repeat length is thought to cause FXPOI, due to the production of a polyglycine-containing FMR1 protein, FMRpolyG. Peripheral blood monocyte cells (PBMCs) and granulosa cells (GCs) were collected to detect FMRpolyG and its cell type-specific expression in FMR1 PM carriers by immunofluorescence staining (IF), Western blotting (WB), and flow cytometric analysis (FACS). For the first time, FMRpolyG aggregates were detected as ubiquitin-positive inclusions in PBMCs from PM carriers, whereas only a weak signal without inclusions was detected in the controls. The expression pattern of FMRpolyG in GCs was comparable to that in the lymphocytes. We detected FMRpolyG as a 15- to 25-kDa protein in the PBMCs from two FMR1 PM carriers, with 124 and 81 CGG repeats. Flow cytometric analysis revealed that FMRpolyG was significantly higher in the T cells from PM carriers than in those from non-PM carriers. The detection of FMRpolyG aggregates in the peripheral blood and granulosa cells of PM carriers suggests that it may have a toxic potential and an immunological role in ovarian damage in the development of FXPOI.
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Orsucci D, Lorenzetti L, Baldinotti F, Rossi A, Vitolo E, Gheri FL, Napolitano A, Tintori G, Vista M. Fragile X-Associated Tremor/Ataxia Syndrome (FXTAS): A Gender Perspective. J Clin Med 2022; 11:jcm11041002. [PMID: 35207276 PMCID: PMC8876035 DOI: 10.3390/jcm11041002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2021] [Revised: 01/29/2022] [Accepted: 02/11/2022] [Indexed: 11/22/2022] Open
Abstract
Although larger trinucleotide expansions give rise to a neurodevelopmental disorder called fragile X syndrome, fragile X-associated tremor/ataxia syndrome (FXTAS) is a late-onset neurodegenerative disorder caused by a “premutation” (55–200 CGG repeats) in the FMR1 gene. FXTAS is one of the more common single-gene forms of late-onset ataxia and tremor that may have a more complex development in women, with atypical presentations. After a brief presentation of the atypical case of an Italian woman with FXTAS, who had several paroxysmal episodes suggestive of acute cerebellar and/or brainstem dysfunction, this article will revise the phenotype of FXTAS in women. Especially in females, FXTAS has a broad spectrum of symptoms, ranging from relatively severe diseases in mid-adulthood to mild cases beginning in later life. Female FXTAS and male FXTAS have a different symptomatic spectrum, and studies on the fragile X premutation should be conducted separately on women or men. Hopefully, a better understanding of the molecular processes involved in the polymorphic features of FXTAS will lead to more specific and effective therapies for this complex disorder.
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Affiliation(s)
- Daniele Orsucci
- Unit of Neurology, San Luca Hospital, Via Lippi-Francesconi, 55100 Lucca, Italy;
- Correspondence: or
| | - Lucia Lorenzetti
- Unit of Internal Medicine, Santa Croce Hospital, 55032 Castelnuovo Garfagnana, Lucca, Italy; (L.L.); (E.V.); (F.L.G.); (G.T.)
| | - Fulvia Baldinotti
- Laboratory of Molecular Genetics, University Hospital of Pisa, 56126 Pisa, Italy;
| | - Andrea Rossi
- Medical Affairs and Scientific Communications, 1260 Nyon, Switzerland;
| | - Edoardo Vitolo
- Unit of Internal Medicine, Santa Croce Hospital, 55032 Castelnuovo Garfagnana, Lucca, Italy; (L.L.); (E.V.); (F.L.G.); (G.T.)
| | - Fabio Luigi Gheri
- Unit of Internal Medicine, Santa Croce Hospital, 55032 Castelnuovo Garfagnana, Lucca, Italy; (L.L.); (E.V.); (F.L.G.); (G.T.)
| | | | - Giancarlo Tintori
- Unit of Internal Medicine, Santa Croce Hospital, 55032 Castelnuovo Garfagnana, Lucca, Italy; (L.L.); (E.V.); (F.L.G.); (G.T.)
| | - Marco Vista
- Unit of Neurology, San Luca Hospital, Via Lippi-Francesconi, 55100 Lucca, Italy;
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8
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Schröder C, Horsthemke B, Depienne C. GC-rich repeat expansions: associated disorders and mechanisms. MED GENET-BERLIN 2022. [DOI: 10.1515/medgen-2021-2099] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Abstract
Noncoding repeat expansions are a well-known cause of genetic disorders mainly affecting the central nervous system. Missed by most standard technologies used in routine diagnosis, pathogenic noncoding repeat expansions have to be searched for using specific techniques such as repeat-primed PCR or specific bioinformatics tools applied to genome data, such as ExpansionHunter. In this review, we focus on GC-rich repeat expansions, which represent at least one third of all noncoding repeat expansions described so far. GC-rich expansions are mainly located in regulatory regions (promoter, 5′ untranslated region, first intron) of genes and can lead to either a toxic gain-of-function mediated by RNA toxicity and/or repeat-associated non-AUG (RAN) translation, or a loss-of-function of the associated gene, depending on their size and their methylation status. We herein review the clinical and molecular characteristics of disorders associated with these difficult-to-detect expansions.
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Affiliation(s)
- Christopher Schröder
- Institute of Human Genetics , University Hospital Essen, University of Duisburg-Essen , Essen , Germany
| | - Bernhard Horsthemke
- Institute of Human Genetics , University Hospital Essen, University of Duisburg-Essen , Essen , Germany
| | - Christel Depienne
- Institute of Human Genetics , University Hospital Essen, University of Duisburg-Essen , Essen , Germany
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9
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Depienne C, Mandel JL. 30 years of repeat expansion disorders: What have we learned and what are the remaining challenges? Am J Hum Genet 2021; 108:764-785. [PMID: 33811808 DOI: 10.1016/j.ajhg.2021.03.011] [Citation(s) in RCA: 138] [Impact Index Per Article: 46.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Accepted: 03/05/2021] [Indexed: 12/13/2022] Open
Abstract
Tandem repeats represent one of the most abundant class of variations in human genomes, which are polymorphic by nature and become highly unstable in a length-dependent manner. The expansion of repeat length across generations is a well-established process that results in human disorders mainly affecting the central nervous system. At least 50 disorders associated with expansion loci have been described to date, with half recognized only in the last ten years, as prior methodological difficulties limited their identification. These limitations still apply to the current widely used molecular diagnostic methods (exome or gene panels) and thus result in missed diagnosis detrimental to affected individuals and their families, especially for disorders that are very rare and/or clinically not recognizable. Most of these disorders have been identified through family-driven approaches and many others likely remain to be identified. The recent development of long-read technologies provides a unique opportunity to systematically investigate the contribution of tandem repeats and repeat expansions to the genetic architecture of human disorders. In this review, we summarize the current and most recent knowledge about the genetics of repeat expansion disorders and the diversity of their pathophysiological mechanisms and outline the perspectives of developing personalized treatments in the future.
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