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Agusti I, Alvarez-Mora MI, Wijngaard R, Borras A, Barcos T, Peralta S, Guimera M, Goday A, Manau D, Rodriguez-Revenga L. Correlation of FMR4 expression levels to ovarian reserve markers in FMR1 premutation carriers. J Ovarian Res 2024; 17:103. [PMID: 38760837 PMCID: PMC11100203 DOI: 10.1186/s13048-024-01425-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2023] [Accepted: 04/25/2024] [Indexed: 05/19/2024] Open
Abstract
BACKGROUND Fragile X-associated primary ovarian insufficiency (FXPOI), characterized by amenorrhea before age 40 years, occurs in 20% of female FMR1 premutation carriers. Presently, there are no molecular or biomarkers that can help predicting which FMR1 premutation women will develop FXPOI. We previously demonstrated that high FMR4 levels can discriminate between FMR1 premutation carriers with and without FXPOI. In the present study the relationship between the expression levels of FMR4 and the ovarian reserve markers was assessed in female FMR1 premutation carriers under age of 35 years. METHODS We examined the association between FMR4 transcript levels and the measures of total antral follicle count (AFC) and serum anti-müllerian hormone (AMH) levels as markers of ovarian follicle reserve. RESULTS Results revealed a negative association between FMR4 levels and AMH (r = 0.45) and AFC (r = 0.64). Statistically significant higher FMR4 transcript levels were found among those FMR1 premutation women with both, low AFCs and AMH levels. CONCLUSIONS These findings reinforce previous studies supporting the association between high levels of FMR4 and the risk of developing FXPOI in FMR1 premutation carriers.
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Affiliation(s)
- Ines Agusti
- Clinical Institute of Gynecology, Obstetrics and Neonatology (ICGON), Hospital Clinic of Barcelona and FCRB-Institut de Investigacions Biomediques August Pi iSunyer (IDIBAPS), Barcelona, Spain
| | - Maria Isabel Alvarez-Mora
- Biochemistry and Molecular Genetics Department, Hospital Clinic of Barcelona and FCRB- Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), C/Villarroel, 170, Barcelona, 08036, Spain
- CIBER of Rare Diseases, Instituto de Salud Carlos III, Madrid, Spain
| | - Robin Wijngaard
- Department of Human Genetics, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Radboud University, Nijmegen, The Netherlands
| | - Aina Borras
- Clinical Institute of Gynecology, Obstetrics and Neonatology (ICGON), Hospital Clinic of Barcelona and FCRB-Institut de Investigacions Biomediques August Pi iSunyer (IDIBAPS), Barcelona, Spain
| | - Tamara Barcos
- Biochemistry and Molecular Genetics Department, Hospital Clinic of Barcelona and FCRB- Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), C/Villarroel, 170, Barcelona, 08036, Spain
| | - Sara Peralta
- Clinical Institute of Gynecology, Obstetrics and Neonatology (ICGON), Hospital Clinic of Barcelona and FCRB-Institut de Investigacions Biomediques August Pi iSunyer (IDIBAPS), Barcelona, Spain
| | - Marta Guimera
- Clinical Institute of Gynecology, Obstetrics and Neonatology (ICGON), Hospital Clinic of Barcelona and FCRB-Institut de Investigacions Biomediques August Pi iSunyer (IDIBAPS), Barcelona, Spain
| | - Anna Goday
- Clinical Institute of Gynecology, Obstetrics and Neonatology (ICGON), Hospital Clinic of Barcelona and FCRB-Institut de Investigacions Biomediques August Pi iSunyer (IDIBAPS), Barcelona, Spain
| | - Dolors Manau
- Clinical Institute of Gynecology, Obstetrics and Neonatology (ICGON), Hospital Clinic of Barcelona and FCRB-Institut de Investigacions Biomediques August Pi iSunyer (IDIBAPS), Barcelona, Spain
| | - Laia Rodriguez-Revenga
- Biochemistry and Molecular Genetics Department, Hospital Clinic of Barcelona and FCRB- Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), C/Villarroel, 170, Barcelona, 08036, Spain.
- CIBER of Rare Diseases, Instituto de Salud Carlos III, Madrid, Spain.
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Ashraf D, Khan MR, Dawson TM, Dawson VL. Protein Translation in the Pathogenesis of Parkinson's Disease. Int J Mol Sci 2024; 25:2393. [PMID: 38397070 PMCID: PMC10888601 DOI: 10.3390/ijms25042393] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2024] [Revised: 02/15/2024] [Accepted: 02/17/2024] [Indexed: 02/25/2024] Open
Abstract
In recent years, research into Parkinson's disease and similar neurodegenerative disorders has increasingly suggested that these conditions are synonymous with failures in proteostasis. However, the spotlight of this research has remained firmly focused on the tail end of proteostasis, primarily aggregation, misfolding, and degradation, with protein translation being comparatively overlooked. Now, there is an increasing body of evidence supporting a potential role for translation in the pathogenesis of PD, and its dysregulation is already established in other similar neurodegenerative conditions. In this paper, we consider how altered protein translation fits into the broader picture of PD pathogenesis, working hand in hand to compound the stress placed on neurons, until this becomes irrecoverable. We will also consider molecular players of interest, recent evidence that suggests that aggregates may directly influence translation in PD progression, and the implications for the role of protein translation in our development of clinically useful diagnostics and therapeutics.
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Affiliation(s)
- Daniyal Ashraf
- Neuroregeneration and Stem Cell Programs, Institute for Cell Engineering, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA; (D.A.); (M.R.K.)
- School of Clinical Medicine, University of Cambridge, Cambridge Biomedical Campus, Box 111, Cambridge CB2 0SP, UK
| | - Mohammed Repon Khan
- Neuroregeneration and Stem Cell Programs, Institute for Cell Engineering, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA; (D.A.); (M.R.K.)
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
- Diana Helis Henry Medical Research Foundation, New Orleans, LA 70130, USA
| | - Ted M. Dawson
- Neuroregeneration and Stem Cell Programs, Institute for Cell Engineering, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA; (D.A.); (M.R.K.)
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
- Diana Helis Henry Medical Research Foundation, New Orleans, LA 70130, USA
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
- Department of Pharmacology and Molecular Sciences, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Valina L. Dawson
- Neuroregeneration and Stem Cell Programs, Institute for Cell Engineering, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA; (D.A.); (M.R.K.)
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
- Diana Helis Henry Medical Research Foundation, New Orleans, LA 70130, USA
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
- Department of Physiology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
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3
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Aishworiya R, Hwang YH, Santos E, Hayward B, Usdin K, Durbin-Johnson B, Hagerman R, Tassone F. Clinical implications of somatic allele expansion in female FMR1 premutation carriers. Sci Rep 2023; 13:7050. [PMID: 37120588 PMCID: PMC10148869 DOI: 10.1038/s41598-023-33528-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2022] [Accepted: 04/14/2023] [Indexed: 05/01/2023] Open
Abstract
Carriers of a premutation allele (PM) in the FMR1 gene are at risk of developing a number of Fragile X premutation asssociated disorders (FXPAC), including Fragile X-associated Tremor/Ataxia Syndrome (FXTAS), Fragile X-associated Primary Ovarian Insufficiency (FXPOI), and Fragile X-associated neuropsychiatric disorders (FXAND). We have recently reported somatic CGG allele expansion in female PM; however, its clinical significance remains unclear. The aim of this study was to examine the potential clinical association between somatic FMR1 allele instability and PM associated disorders. Participants comprised of 424 female PM carriers age 0.3- 90 years. FMR1 molecular measures and clinical information on the presence of medical conditions, were determined for all subjects for primary analysis. Two sub-groups of participants (age ≥ 25, N = 377 and age ≥ 50, N = 134) were used in the analysis related to presence of FXPOI and FXTAS, respectively. Among all participants (N = 424), the degree of instability (expansion) was significantly higher (median 2.5 vs 2.0, P = 0.026) in participants with a diagnosis of attention deficit hyperactivity disorder (ADHD) compared to those without. FMR1 mRNA expression was significantly higher in subjects with any psychiatric disorder diagnosis (P = 0.0017); specifically, in those with ADHD (P = 0.009), and with depression (P = 0.025). Somatic FMR1 expansion was associated with the presence of ADHD in female PM and FMR1 mRNA levels were associated with the presence of mental health disorders. The findings of our research are innovative as they suggest a potential role of the CGG expansion in the clinical phenotype of PM and may potentially guide clinical prognosis and management.
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Affiliation(s)
- Ramkumar Aishworiya
- Medical Investigation of Neurodevelopmental Disorders (MIND) Institute, University of California Davis, 2825 50Th Street, Sacramento, CA, 95817, USA
- Khoo Teck Puat-National University Children's Medical Institute, National University Health System, 5 Lower Kent Ridge Road, Singapore, 119074, Singapore
- Department of Pediatrics, Yong Loo Lin School of Medicine, National University of Singapore, 10 Medical Drive, Singapore, 117597, Singapore
| | - Ye Hyun Hwang
- Department of Biochemistry and Molecular Medicine, University of California Davis, School of Medicine, 4610 X St, Sacramento, CA, 95817, USA
| | - Ellery Santos
- Medical Investigation of Neurodevelopmental Disorders (MIND) Institute, University of California Davis, 2825 50Th Street, Sacramento, CA, 95817, USA
- Department of Pediatrics, University of California Davis, School of Medicine, 4610 X St, Sacramento, CA, 95817, USA
| | - Bruce Hayward
- Laboratory of Cell and Molecular Biology, Digestive and Kidney Diseases, National Institute of Diabetes, 9000 Rockville Pike, Bethesda, MD, 20892, USA
| | - Karen Usdin
- Laboratory of Cell and Molecular Biology, Digestive and Kidney Diseases, National Institute of Diabetes, 9000 Rockville Pike, Bethesda, MD, 20892, USA
| | - Blythe Durbin-Johnson
- Department of Public Health Sciences, University of California, Davis, School of Medicine, 4610 X St, Sacramento, CA, 95817, USA
| | - Randi Hagerman
- Medical Investigation of Neurodevelopmental Disorders (MIND) Institute, University of California Davis, 2825 50Th Street, Sacramento, CA, 95817, USA
- Department of Pediatrics, University of California Davis, School of Medicine, 4610 X St, Sacramento, CA, 95817, USA
| | - Flora Tassone
- Medical Investigation of Neurodevelopmental Disorders (MIND) Institute, University of California Davis, 2825 50Th Street, Sacramento, CA, 95817, USA.
- Department of Biochemistry and Molecular Medicine, University of California Davis, School of Medicine, 4610 X St, Sacramento, CA, 95817, USA.
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Neurodegenerative diseases associated with non-coding CGG tandem repeat expansions. Nat Rev Neurol 2022; 18:145-157. [PMID: 35022573 DOI: 10.1038/s41582-021-00612-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/15/2021] [Indexed: 02/07/2023]
Abstract
Non-coding CGG repeat expansions cause multiple neurodegenerative disorders, including fragile X-associated tremor/ataxia syndrome, neuronal intranuclear inclusion disease, oculopharyngeal myopathy with leukodystrophy, and oculopharyngodistal myopathy. The underlying genetic causes of several of these diseases have been identified only in the past 2-3 years. These expansion disorders have substantial overlapping clinical, neuroimaging and histopathological features. The shared features suggest common mechanisms that could have implications for the development of therapies for this group of diseases - similar therapeutic strategies or drugs may be effective for various neurodegenerative disorders induced by non-coding CGG expansions. In this Review, we provide an overview of clinical and pathological features of these CGG repeat expansion diseases and consider the likely pathological mechanisms, including RNA toxicity, CGG repeat-associated non-AUG-initiated translation, protein aggregation and mitochondrial impairment. We then discuss future research needed to improve the identification and diagnosis of CGG repeat expansion diseases, to improve modelling of these diseases and to understand their pathogenesis. We also consider possible therapeutic strategies. Finally, we propose that CGG repeat expansion diseases may represent manifestations of a single underlying neuromyodegenerative syndrome in which different organs are affected to different extents depending on the gene location of the repeat expansion.
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Rosario R, Anderson R. The molecular mechanisms that underlie fragile X-associated premature ovarian insufficiency: is it RNA or protein based? Mol Hum Reprod 2021; 26:727-737. [PMID: 32777047 PMCID: PMC7566375 DOI: 10.1093/molehr/gaaa057] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2020] [Revised: 08/03/2020] [Indexed: 01/30/2023] Open
Abstract
The FMR1 gene contains a polymorphic CGG trinucleotide sequence within its 5′ untranslated region. More than 200 CGG repeats (termed a full mutation) underlie the severe neurodevelopmental condition fragile X syndrome, while repeat lengths that range between 55 and 200 (termed a premutation) result in the conditions fragile X-associated tremor/ataxia syndrome and fragile X-associated premature ovarian insufficiency (FXPOI). Premutations in FMR1 are the most common monogenic cause of premature ovarian insufficiency and are routinely tested for clinically; however, the mechanisms that contribute to the pathology are still largely unclear. As studies in this field move towards unravelling the molecular mechanisms involved in FXPOI aetiology, we review the evidence surrounding the two main theories which describe an RNA toxic gain-of-function mechanism, resulting in the loss of function of RNA-binding proteins, or a protein-based mechanism, where repeat-associated non-AUG translation leads to the formation of an abnormal polyglycine containing protein, called FMRpolyG.
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Affiliation(s)
- Roseanne Rosario
- MRC Centre for Reproductive Health, Queens Medical Research Institute, University of Edinburgh, Edinburgh, UK
| | - Richard Anderson
- MRC Centre for Reproductive Health, Queens Medical Research Institute, University of Edinburgh, Edinburgh, UK
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6
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Ajjugal Y, Kolimi N, Rathinavelan T. Secondary structural choice of DNA and RNA associated with CGG/CCG trinucleotide repeat expansion rationalizes the RNA misprocessing in FXTAS. Sci Rep 2021; 11:8163. [PMID: 33854084 PMCID: PMC8046799 DOI: 10.1038/s41598-021-87097-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2020] [Accepted: 03/22/2021] [Indexed: 11/09/2022] Open
Abstract
CGG tandem repeat expansion in the 5'-untranslated region of the fragile X mental retardation-1 (FMR1) gene leads to unusual nucleic acid conformations, hence causing genetic instabilities. We show that the number of G…G (in CGG repeat) or C…C (in CCG repeat) mismatches (other than A…T, T…A, C…G and G…C canonical base pairs) dictates the secondary structural choice of the sense and antisense strands of the FMR1 gene and their corresponding transcripts in fragile X-associated tremor/ataxia syndrome (FXTAS). The circular dichroism (CD) spectra and electrophoretic mobility shift assay (EMSA) reveal that CGG DNA (sense strand of the FMR1 gene) and its transcript favor a quadruplex structure. CD, EMSA and molecular dynamics (MD) simulations also show that more than four C…C mismatches cannot be accommodated in the RNA duplex consisting of the CCG repeat (antisense transcript); instead, it favors an i-motif conformational intermediate. Such a preference for unusual secondary structures provides a convincing justification for the RNA foci formation due to the sequestration of RNA-binding proteins to the bidirectional transcripts and the repeat-associated non-AUG translation that are observed in FXTAS. The results presented here also suggest that small molecule modulators that can destabilize FMR1 CGG DNA and RNA quadruplex structures could be promising candidates for treating FXTAS.
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Affiliation(s)
- Yogeeshwar Ajjugal
- Department of Biotechnology, Indian Institute of Technology Hyderabad, Kandi, Telangana State, 502285, India
| | - Narendar Kolimi
- Department of Biotechnology, Indian Institute of Technology Hyderabad, Kandi, Telangana State, 502285, India
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7
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Laboratory testing for fragile X, 2021 revision: a technical standard of the American College of Medical Genetics and Genomics (ACMG). Genet Med 2021; 23:799-812. [PMID: 33795824 DOI: 10.1038/s41436-021-01115-y] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Revised: 02/01/2021] [Accepted: 02/02/2021] [Indexed: 11/08/2022] Open
Abstract
Molecular genetic testing of the FMR1 gene is commonly performed in clinical laboratories. Pathogenic variants in the FMR1 gene are associated with fragile X syndrome, fragile X-associated tremor ataxia syndrome (FXTAS), and fragile X-associated primary ovarian insufficiency (FXPOI). This document provides updated information regarding FMR1 pathogenic variants, including prevalence, genotype-phenotype correlations, and variant nomenclature. Methodological considerations are provided for Southern blot analysis and polymerase chain reaction (PCR) amplification of FMR1, including triplet repeat-primed and methylation-specific PCR.The American College of Medical Genetics and Genomics (ACMG) Laboratory Quality Assurance Committee has the mission of maintaining high technical standards for the performance and interpretation of genetic tests. In part, this is accomplished by the publication of the document ACMG Technical Standards for Clinical Genetics Laboratories, which is now maintained online ( http://www.acmg.net ). This subcommittee also reviews the outcome of national proficiency testing in the genetics area and may choose to focus on specific diseases or methodologies in response to those results. Accordingly, the subcommittee selected fragile X syndrome to be the first topic in a series of supplemental sections, recognizing that it is one of the most frequently ordered genetic tests and that it has many alternative methods with different strengths and weaknesses. This document is the fourth update to the original standards and guidelines for fragile X testing that were published in 2001, with revisions in 2005 and 2013, respectively.This versionClarifies the clinical features associated with different FMRI variants (Section 2.3)Discusses important reporting considerations (Section 3.3.1.3)Provides updates on technology (Section 4.1).
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Haify SN, Mankoe RSD, Boumeester V, van der Toorn EC, Verhagen RFM, Willemsen R, Hukema RK, Bosman LWJ. Lack of a Clear Behavioral Phenotype in an Inducible FXTAS Mouse Model Despite the Presence of Neuronal FMRpolyG-Positive Aggregates. Front Mol Biosci 2020; 7:599101. [PMID: 33381520 PMCID: PMC7768028 DOI: 10.3389/fmolb.2020.599101] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2020] [Accepted: 11/23/2020] [Indexed: 11/25/2022] Open
Abstract
Fragile X-associated tremor/ataxia syndrome (FXTAS) is a rare neurodegenerative disorder caused by a 55–200 CGG repeat expansion in the 5′ untranslated region of the Fragile X Mental Retardation 1 (FMR1) gene. FXTAS is characterized by progressive cerebellar ataxia, Parkinsonism, intention tremors and cognitive decline. The main neuropathological hallmark of FXTAS is the presence of ubiquitin-positive intranuclear inclusions in neurons and astrocytes throughout the brain. The molecular pathology of FXTAS involves the presence of 2 to 8-fold elevated levels of FMR1 mRNA, and of a repeat-associated non-AUG (RAN) translated polyglycine peptide (FMRpolyG). Increased levels of FMR1 mRNA containing an expanded CGG repeat can result in cellular toxicity by an RNA gain-of-function mechanism. The increased levels of CGG repeat-expanded FMR1 transcripts may create RNA foci that sequester important cellular proteins, including RNA-binding proteins and FMRpolyG, in intranuclear inclusions. To date, it is unclear whether the FMRpolyG-positive intranuclear inclusions are a cause or a consequence of FXTAS disease pathology. In this report we studied the relation between the presence of neuronal intranuclear inclusions and behavioral deficits using an inducible mouse model for FXTAS. Neuronal intranuclear inclusions were observed 4 weeks after dox-induction. After 12 weeks, high numbers of FMRpolyG-positive intranuclear inclusions could be detected in the hippocampus and striatum, but no clear signs of behavioral deficits related to these specific brain regions were found. In conclusion, the observations in our inducible mouse model for FXTAS suggest a lack of correlation between the presence of intranuclear FMRpolyG-positive aggregates in brain regions and specific behavioral phenotypes.
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Affiliation(s)
- Saif N Haify
- Department of Clinical Genetics, Erasmus MC, Rotterdam, Netherlands
| | - Ruchira S D Mankoe
- Department of Clinical Genetics, Erasmus MC, Rotterdam, Netherlands.,Department of Neuroscience, Erasmus MC, Rotterdam, Netherlands
| | | | | | - Rob F M Verhagen
- Department of Clinical Genetics, Erasmus MC, Rotterdam, Netherlands
| | - Rob Willemsen
- Department of Clinical Genetics, Erasmus MC, Rotterdam, Netherlands
| | - Renate K Hukema
- Department of Clinical Genetics, Erasmus MC, Rotterdam, Netherlands.,Department of Health Care Studies, Rotterdam University of Applied Sciences, Rotterdam, Netherlands
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9
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Lalonde E, Rentas S, Lin F, Dulik MC, Skraban CM, Spinner NB. Genomic Diagnosis for Pediatric Disorders: Revolution and Evolution. Front Pediatr 2020; 8:373. [PMID: 32733828 PMCID: PMC7360789 DOI: 10.3389/fped.2020.00373] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/26/2019] [Accepted: 06/02/2020] [Indexed: 12/14/2022] Open
Abstract
Powerful, recent advances in technologies to analyze the genome have had a profound impact on the practice of medical genetics, both in the laboratory and in the clinic. Increasing utilization of genome-wide testing such as chromosomal microarray analysis and exome sequencing have lead a shift toward a "genotype-first" approach. Numerous techniques are now available to diagnose a particular syndrome or phenotype, and while traditional techniques remain efficient tools in certain situations, higher-throughput technologies have become the de facto laboratory tool for diagnosis of most conditions. However, selecting the right assay or technology is challenging, and the wrong choice may lead to prolonged time to diagnosis, or even a missed diagnosis. In this review, we will discuss current core technologies for the diagnosis of classic genetic disorders to shed light on the benefits and disadvantages of these strategies, including diagnostic efficiency, variant interpretation, and secondary findings. Finally, we review upcoming technologies posed to impart further changes in the field of genetic diagnostics as we move toward "genome-first" practice.
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Affiliation(s)
- Emilie Lalonde
- Division of Genomic Diagnostics, Department of Pathology and Laboratory Medicine, School of Medicine, Children's Hospital of Philadelphia, University of Pennsylvania, Philadelphia, PA, United States
| | - Stefan Rentas
- Division of Genomic Diagnostics, Department of Pathology and Laboratory Medicine, School of Medicine, Children's Hospital of Philadelphia, University of Pennsylvania, Philadelphia, PA, United States
| | - Fumin Lin
- Division of Genomic Diagnostics, Department of Pathology and Laboratory Medicine, School of Medicine, Children's Hospital of Philadelphia, University of Pennsylvania, Philadelphia, PA, United States
| | - Matthew C. Dulik
- Division of Genomic Diagnostics, Department of Pathology and Laboratory Medicine, School of Medicine, Children's Hospital of Philadelphia, University of Pennsylvania, Philadelphia, PA, United States
| | - Cara M. Skraban
- Division of Human Genetics, Department of Pediatrics, School of Medicine, Children's Hospital of Philadelphia, University of Pennsylvania, Philadelphia, PA, United States
| | - Nancy B. Spinner
- Division of Genomic Diagnostics, Department of Pathology and Laboratory Medicine, School of Medicine, Children's Hospital of Philadelphia, University of Pennsylvania, Philadelphia, PA, United States
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10
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Božič T, Zalar M, Rogelj B, Plavec J, Šket P. Structural Diversity of Sense and Antisense RNA Hexanucleotide Repeats Associated with ALS and FTLD. Molecules 2020; 25:molecules25030525. [PMID: 31991801 PMCID: PMC7037139 DOI: 10.3390/molecules25030525] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Revised: 01/17/2020] [Accepted: 01/24/2020] [Indexed: 12/14/2022] Open
Abstract
The hexanucleotide expansion GGGGCC located in C9orf72 gene represents the most common genetic cause of amyotrophic lateral sclerosis (ALS) and frontotemporal lobar dementia (FTLD). Since the discovery one of the non-exclusive mechanisms of expanded hexanucleotide G4C2 repeats involved in ALS and FTLD is RNA toxicity, which involves accumulation of pathological sense and antisense RNA transcripts. Formed RNA foci sequester RNA-binding proteins, causing their mislocalization and, thus, diminishing their biological function. Therefore, structures adopted by pathological RNA transcripts could have a key role in pathogenesis of ALS and FTLD. Utilizing NMR spectroscopy and complementary methods, we examined structures adopted by both guanine-rich sense and cytosine-rich antisense RNA oligonucleotides with four hexanucleotide repeats. While both oligonucleotides tend to form dimers and hairpins, the equilibrium of these structures differs with antisense oligonucleotide being more sensitive to changes in pH and sense oligonucleotide to temperature. In the presence of K+ ions, guanine-rich sense RNA oligonucleotide also adopts secondary structures called G-quadruplexes. Here, we also observed, for the first time, that antisense RNA oligonucleotide forms i-motifs under specific conditions. Moreover, simultaneous presence of sense and antisense RNA oligonucleotides promotes formation of heterodimer. Studied structural diversity of sense and antisense RNA transcripts not only further depicts the complex nature of neurodegenerative diseases but also reveals potential targets for drug design in treatment of ALS and FTLD.
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Affiliation(s)
- Tim Božič
- Slovenian NMR Centre, National Institute of Chemistry, Hajdrihova 19, SI-1000 Ljubljana, Slovenia; (T.B.); (M.Z.)
| | - Matja Zalar
- Slovenian NMR Centre, National Institute of Chemistry, Hajdrihova 19, SI-1000 Ljubljana, Slovenia; (T.B.); (M.Z.)
| | - Boris Rogelj
- Department of Biotechnology, Jožef Stefan Institute, Jamova 39, SI-1000 Ljubljana, Slovenia;
- Biomedical Research Institute BRIS, Puhova 10, SI-1000 Ljubljana, Slovenia
| | - Janez Plavec
- Slovenian NMR Centre, National Institute of Chemistry, Hajdrihova 19, SI-1000 Ljubljana, Slovenia; (T.B.); (M.Z.)
- EN-FIST Center of Excellence, Trg OF 13, SI-1000 Ljubljana, Slovenia
- Faculty of Chemistry and Chemical Technology, University of Ljubljana, Večna pot 113, SI-1000 Ljubljana, Slovenia
- Correspondence: (P.Š.); (J.P.); Tel.: +386-1-4760223 (P.Š.); +386-1-4760353 (J.P.)
| | - Primož Šket
- Slovenian NMR Centre, National Institute of Chemistry, Hajdrihova 19, SI-1000 Ljubljana, Slovenia; (T.B.); (M.Z.)
- Correspondence: (P.Š.); (J.P.); Tel.: +386-1-4760223 (P.Š.); +386-1-4760353 (J.P.)
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11
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Bajc Česnik A, Darovic S, Prpar Mihevc S, Štalekar M, Malnar M, Motaln H, Lee YB, Mazej J, Pohleven J, Grosch M, Modic M, Fonovič M, Turk B, Drukker M, Shaw CE, Rogelj B. Nuclear RNA foci from C9ORF72 expansion mutation form paraspeckle-like bodies. J Cell Sci 2019; 132:jcs.224303. [PMID: 30745340 DOI: 10.1242/jcs.224303] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2018] [Accepted: 01/31/2019] [Indexed: 12/12/2022] Open
Abstract
The GGGGCC (G4C2) repeat expansion mutation in the C9ORF72 gene is the most common genetic cause of frontotemporal dementia (FTD) and amyotrophic lateral sclerosis (ALS). Transcription of the repeat and formation of nuclear RNA foci, which sequester specific RNA-binding proteins, is one of the possible pathological mechanisms. Here, we show that (G4C2) n repeat RNA predominantly associates with essential paraspeckle proteins SFPQ, NONO, RBM14, FUS and hnRNPH and colocalizes with known paraspeckle-associated RNA hLinc-p21. As formation of paraspeckles in motor neurons has been associated with early phases of ALS, we investigated the extent of similarity between paraspeckles and (G4C2) n RNA foci. Overexpression of (G4C2)72 RNA results in their increased number and colocalization with SFPQ-stained nuclear bodies. These paraspeckle-like (G4C2)72 RNA foci form independently of the known paraspeckle scaffold, the long non-coding RNA NEAT1 Moreover, the knockdown of SFPQ protein in C9ORF72 expansion mutation-positive fibroblasts significantly reduces the number of (G4C2) n RNA foci. In conclusion, (G4C2) n RNA foci have characteristics of paraspeckles, which suggests that both RNA foci and paraspeckles play roles in FTD and ALS, and implies approaches for regulation of their formation.
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Affiliation(s)
- Ana Bajc Česnik
- Department of Biotechnology, Jozef Stefan Institute, Ljubljana 1000, Slovenia.,Graduate School of Biomedicine, Faculty of Medicine, University of Ljubljana, Ljubljana 1000, Slovenia
| | - Simona Darovic
- Department of Biotechnology, Jozef Stefan Institute, Ljubljana 1000, Slovenia.,Biomedical Research Institute BRIS, Ljubljana 1000, Slovenia
| | - Sonja Prpar Mihevc
- Department of Biotechnology, Jozef Stefan Institute, Ljubljana 1000, Slovenia
| | - Maja Štalekar
- Department of Biotechnology, Jozef Stefan Institute, Ljubljana 1000, Slovenia.,Biomedical Research Institute BRIS, Ljubljana 1000, Slovenia
| | - Mirjana Malnar
- Department of Biotechnology, Jozef Stefan Institute, Ljubljana 1000, Slovenia.,Graduate School of Biomedicine, Faculty of Medicine, University of Ljubljana, Ljubljana 1000, Slovenia
| | - Helena Motaln
- Department of Biotechnology, Jozef Stefan Institute, Ljubljana 1000, Slovenia
| | - Youn-Bok Lee
- Department of Basic and Clinical Neuroscience, Institute of Psychiatry, King's College London, London SE5 9RT, UK
| | - Julija Mazej
- Department of Biotechnology, Jozef Stefan Institute, Ljubljana 1000, Slovenia.,Faculty of Chemistry and Chemical Technology, University of Ljubljana, Ljubljana 1000, Slovenia
| | - Jure Pohleven
- Department of Biotechnology, Jozef Stefan Institute, Ljubljana 1000, Slovenia
| | - Markus Grosch
- Helmholtz Center Munich, Institute of Stem Cell Research, German Research Center for Environmental Health, Neuherberg 85764, Germany
| | - Miha Modic
- Helmholtz Center Munich, Institute of Stem Cell Research, German Research Center for Environmental Health, Neuherberg 85764, Germany
| | - Marko Fonovič
- Department of Biochemistry and Molecular and Structural Biology, Jozef Stefan Institute, Ljubljana 1000, Slovenia
| | - Boris Turk
- Department of Biochemistry and Molecular and Structural Biology, Jozef Stefan Institute, Ljubljana 1000, Slovenia
| | - Micha Drukker
- Helmholtz Center Munich, Institute of Stem Cell Research, German Research Center for Environmental Health, Neuherberg 85764, Germany
| | - Christopher E Shaw
- Department of Basic and Clinical Neuroscience, Institute of Psychiatry, King's College London, London SE5 9RT, UK
| | - Boris Rogelj
- Department of Biotechnology, Jozef Stefan Institute, Ljubljana 1000, Slovenia .,Biomedical Research Institute BRIS, Ljubljana 1000, Slovenia.,Faculty of Chemistry and Chemical Technology, University of Ljubljana, Ljubljana 1000, Slovenia
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12
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13
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Beke A, Piko H, Haltrich I, Karcagi V, Rigo J, Molnar MJ, Fekete G. Study of patterns of inheritance of premature ovarian failure syndrome carrying maternal and paternal premutations. BMC MEDICAL GENETICS 2018; 19:113. [PMID: 29986653 PMCID: PMC6038184 DOI: 10.1186/s12881-018-0634-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/04/2017] [Accepted: 06/26/2018] [Indexed: 12/21/2022]
Abstract
BACKGROUND Premature ovarian failure / primary ovarian insufficiency (POF/POI) associated with the mutations of the FMR1 (Fragile-X Mental Retardation 1) gene belongs to the group of the so-called trinucleotide expansion diseases. Our aim was to analyse the relationship between the paternally inherited premutation (PIP) and the maternally inherited premutation (MIP) by the examination of the family members of women with POF, carrying the premutation allele confirmed by molecular genetic testing. METHODS Molecular genetic testing was performed in the patients of the 1st Department of Obstetrics and Gynecology with suspected premature ovarian failure. First we performed the southern blot analyses and for the certified premutation cases we used the Repeat Primed PCR. RESULTS Due to POF/POI, a total of 125 patients underwent genetic testing. The FMR1 gene trinucleotide repeat number was examined in the DNA samples of the patients, and in 15 cases (12%) deviations (CGG repeat number corresponding to premutation or gray zone) were detected. In 6 cases out of the 15 cases the CGG repeat number fell within the range of the so-called gray zone (41-54 CGG repeat) (4.8%, 6/125), and the FMR1 premutation (55-200 CGG repeat) ratio was 7.2% (9/125). In 4 out of the 15 cases we found differences in both alleles, one was a premutation allele, and the other allele showed a repeat number belonging to the gray zone. Out of 15 cases, only maternal inheritance (MIP) was detected in 2 cases, in one case the premutation allele (91 CGG repeat number), while in the other case an allele belonging to the gray zone (41 CGG repeat number) were inherited from their mothers. In 10 out of 15 cases, the patient inherited the premutation allele only from the father (PIP). In 5 out of the 10 cases (50%) the premutation allele was inherited from the father, and the repeat number ranged from 55 to 133. Out of 125 cases, 9 patients had detectable cytogenetic abnormalities (7.2%). CONCLUSIONS The RP-PCR method can be used to define the smaller premutations and the exact CGG number. Due to the quantitative nature of the RP-PCR, it is possible to detect the mosaicism as well.
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Affiliation(s)
- Artur Beke
- 1st Department of Obstetrics and Gynecology, Semmelweis University, Baross u. 27, Budapest, 1428, Hungary.
| | - Henriett Piko
- Institute of Genomic Medicine and Rare Disorders, Semmelweis University, Budapest, Hungary
| | - Iren Haltrich
- 2nd Department of Pediatrics, Semmelweis University fekete, Budapest, Hungary
| | - Veronika Karcagi
- Institute of Genomic Medicine and Rare Disorders, Semmelweis University, Budapest, Hungary
| | - Janos Rigo
- 1st Department of Obstetrics and Gynecology, Semmelweis University, Baross u. 27, Budapest, 1428, Hungary
| | - Maria Judit Molnar
- Institute of Genomic Medicine and Rare Disorders, Semmelweis University, Budapest, Hungary
| | - György Fekete
- 2nd Department of Pediatrics, Semmelweis University fekete, Budapest, Hungary
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14
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Rudich P, Lamitina T. Models and mechanisms of repeat expansion disorders: a worm's eye view. J Genet 2018; 97:665-677. [PMID: 30027902 PMCID: PMC6482835] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The inappropriate genetic expansion of various repetitive DNA sequences underlies over 20 distinct inherited diseases. The genetic context of these repeats in exons, introns and untranslated regions has played a major role in thinking about the mechanisms by which various repeat expansions might cause disease. Repeat expansions in exons are thought to give rise to expanded toxic protein repeats (i.e. polyQ). Repeat expansions in introns and UTRs (i.e. FXTAS) are thought to produce aberrant repeat-bearing RNAs that interact with and sequester a wide variety of essential proteins, resulting in cellular toxicity. However, a new phenomenon termed 'repeat-associated nonAUG dependent (RAN) translation' paints a new and unifying picture of how distinct repeat expansion-bearing RNAs might act as substrates for this noncanonical form of translation, leading to the production of a wide range of repeat sequence-specific-encoded toxic proteins. Here, we review how the model system Caenorhabditis elegans has been utilized to model many repeat disorders and discuss how RAN translation could be a previously unappreciated contributor to the toxicity associated with these different models.
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Affiliation(s)
- Paige Rudich
- Graduate Program in Cell Biology and Molecular Physiology, University of Pittsburgh Medical Center, Pittsburgh, PA 15224, USA.
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Guler GD, Rosenwaks Z, Gerhardt J. Human DNA Helicase B as a Candidate for Unwinding Secondary CGG Repeat Structures at the Fragile X Mental Retardation Gene. Front Mol Neurosci 2018; 11:138. [PMID: 29760651 PMCID: PMC5936766 DOI: 10.3389/fnmol.2018.00138] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2018] [Accepted: 04/04/2018] [Indexed: 12/20/2022] Open
Abstract
The fragile X syndrome (FXS) is caused by a CGG repeat expansion at the fragile X mental retardation (FMR1) gene. FMR1 alleles with more than 200 CGG repeats bear chromosomal fragility when cells experience folate deficiency. CGG repeats were reported to be able to form secondary structures, such as hairpins, in vitro. When such secondary structures are formed, repeats can lead to replication fork stalling even in the absence of any additional perturbation. Indeed, it was recently shown that the replication forks stall at the endogenous FMR1 locus in unaffected and FXS cells, suggesting the formation of secondary repeat structures at the FMR1 gene in vivo. If not dealt with properly replication fork stalling can lead to polymerase slippage and repeat expansion as well as fragile site expression. Despite the presence of repeat structures at the FMR1 locus, chromosomal fragility is only expressed under replicative stress suggesting the existence of potential molecular mechanisms that help the replication fork progress through these repeat regions. DNA helicases are known to aid replication forks progress through repetitive DNA sequences. Yet, the identity of the DNA helicase(s) responsible for unwinding the CGG repeats at FMR1 locus is not known. We found that the human DNA helicase B (HDHB) may provide an answer for this question. We used chromatin-immunoprecipitation assay to study the FMR1 region and common fragile sites (CFS), and asked whether HDHB localizes at replication forks stalled at repetitive regions even in unperturbed cells. HDHB was strongly enriched in S-phase at the repetitive DNA at CFS and FMR1 gene but not in the flanking regions. Taken together, these results suggest that HDHB functions in preventing or repairing stalled replication forks that arise in repeat-rich regions even in unperturbed cells. Furthermore, we discuss the importance and potential role of HDHB and other helicases in the resolution of secondary CGG repeat structures.
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Affiliation(s)
- Gulfem D Guler
- Celgene Quanticel Research, San Francisco, CA, United States
| | - Zev Rosenwaks
- The Ronald O. Perelman and Claudia Cohen Center for Reproductive Medicine, Weill Cornell Medicine, Cornell University, New York, NY, United States
| | - Jeannine Gerhardt
- The Ronald O. Perelman and Claudia Cohen Center for Reproductive Medicine, Weill Cornell Medicine, Cornell University, New York, NY, United States.,Department of Obstetrics and Gynecology, Weill Cornell Medicine, Cornell University, New York, NY, United States
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16
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Hsia GSP, Musso CM, Alvizi L, Brito LA, Kobayashi GS, Pavanello RCM, Zatz M, Gardham A, Wakeling E, Zechi-Ceide RM, Bertola D, Passos-Bueno MR. Complexity of the 5' Untranslated Region of EIF4A3, a Critical Factor for Craniofacial and Neural Development. Front Genet 2018; 9:149. [PMID: 29922329 PMCID: PMC5996909 DOI: 10.3389/fgene.2018.00149] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2018] [Accepted: 04/10/2018] [Indexed: 01/09/2023] Open
Abstract
Repeats in coding and non-coding regions have increasingly been associated with many human genetic disorders, such as Richieri-Costa-Pereira syndrome (RCPS). RCPS, mostly characterized by midline cleft mandible, Robin sequence and limb defects, is an autosomal-recessive acrofacial dysostosis mainly reported in Brazilian patients. This disorder is caused by decreased levels of EIF4A3, mostly due to an increased number of repeats at the EIF4A3 5′UTR. EIF4A3 5′UTR alleles are CG-rich and vary in size and organization of three types of motifs. An exclusive allelic pattern was identified among affected individuals, in which the CGCA-motif is the most prevalent, herein referred as “disease-associated CGCA-20nt motif.” The origin of the pathogenic alleles containing the disease-associated motif, as well as the functional effects of the 5′UTR motifs on EIF4A3 expression, to date, are entirely unknown. Here, we characterized 43 different EIF4A3 5′UTR alleles in a cohort of 380 unaffected individuals. We identified eight heterozygous unaffected individuals harboring the disease-associated CGCA-20nt motif and our haplotype analyses indicate that there are more than one haplotype associated with RCPS. The combined analysis of number, motif organization and haplotypic diversity, as well as the observation of two apparently distinct haplotypes associated with the disease-associated CGCA-20nt motif, suggest that the RCPS alleles might have arisen from independent unequal crossing-over events between ancient alleles at least twice. Moreover, we have shown that the number and sequence of motifs in the 5′UTR region is associated with EIF4A3 repression, which is not mediated by CpG methylation. In conclusion, this study has shown that the large number of repeats in EIF4A3 does not represent a dynamic mutation and RCPS can arise in any population harboring alleles with the CGCA-20nt motif. We also provided further evidence that EIF4A3 5′UTR is a regulatory region and the size and sequence type of the repeats at 5′UTR may contribute to clinical variability in RCPS.
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Affiliation(s)
- Gabriella S P Hsia
- Centro de Estudos do Genoma Humano e Células Tronco, Departamento de Genética e Biologia Evolutiva, Instituto de Biociências, Universidade de São Paulo, São Paulo, Brazil
| | - Camila M Musso
- Centro de Estudos do Genoma Humano e Células Tronco, Departamento de Genética e Biologia Evolutiva, Instituto de Biociências, Universidade de São Paulo, São Paulo, Brazil
| | - Lucas Alvizi
- Centro de Estudos do Genoma Humano e Células Tronco, Departamento de Genética e Biologia Evolutiva, Instituto de Biociências, Universidade de São Paulo, São Paulo, Brazil
| | - Luciano A Brito
- Centro de Estudos do Genoma Humano e Células Tronco, Departamento de Genética e Biologia Evolutiva, Instituto de Biociências, Universidade de São Paulo, São Paulo, Brazil
| | - Gerson S Kobayashi
- Centro de Estudos do Genoma Humano e Células Tronco, Departamento de Genética e Biologia Evolutiva, Instituto de Biociências, Universidade de São Paulo, São Paulo, Brazil
| | - Rita C M Pavanello
- Centro de Estudos do Genoma Humano e Células Tronco, Departamento de Genética e Biologia Evolutiva, Instituto de Biociências, Universidade de São Paulo, São Paulo, Brazil
| | - Mayana Zatz
- Centro de Estudos do Genoma Humano e Células Tronco, Departamento de Genética e Biologia Evolutiva, Instituto de Biociências, Universidade de São Paulo, São Paulo, Brazil
| | - Alice Gardham
- North East Thames Genetics Service, Great Ormond Street Hospital, London, United Kingdom
| | - Emma Wakeling
- North East Thames Genetics Service, Great Ormond Street Hospital, London, United Kingdom
| | - Roseli M Zechi-Ceide
- Hospital de Reabilitação de Anomalias Craniofaciais, Universidade de São Paulo, São Paulo, Brazil
| | - Debora Bertola
- Centro de Estudos do Genoma Humano e Células Tronco, Departamento de Genética e Biologia Evolutiva, Instituto de Biociências, Universidade de São Paulo, São Paulo, Brazil.,Instituto da Criança, Hospital das Clínicas da FMUSP, Universidade de São Paulo, São Paulo, Brazil
| | - Maria Rita Passos-Bueno
- Centro de Estudos do Genoma Humano e Células Tronco, Departamento de Genética e Biologia Evolutiva, Instituto de Biociências, Universidade de São Paulo, São Paulo, Brazil
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Mor-Shaked H, Eiges R. Reevaluation of FMR1 Hypermethylation Timing in Fragile X Syndrome. Front Mol Neurosci 2018; 11:31. [PMID: 29467618 PMCID: PMC5808132 DOI: 10.3389/fnmol.2018.00031] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2017] [Accepted: 01/24/2018] [Indexed: 12/27/2022] Open
Abstract
Fragile X syndrome (FXS) is one of the most common heritable forms of cognitive impairment. It results from a fragile X mental retardation protein (FMRP) protein deficiency caused by a CGG repeat expansion in the 5'-UTR of the X-linked FMR1 gene. Whereas in most individuals the number of CGGs is steady and ranges between 5 and 44 units, in patients it becomes extensively unstable and expands to a length exceeding 200 repeats (full mutation). Interestingly, this disease is exclusively transmitted by mothers who carry a premutation allele (55-200 CGG repeats). When the CGGs reach the FM range, they trigger the spread of abnormal DNA methylation, which coincides with a switch from active to repressive histone modifications. This results in epigenetic gene silencing of FMR1 presumably by a multi-stage, developmentally regulated process. The timing of FMR1 hypermethylation and transcription silencing is still hotly debated. There is evidence that hypermethylation varies considerably between and within the tissues of patients as well as during fetal development, thus supporting the view that FMR1 silencing is a post-zygotic event that is developmentally structured. On the other hand, it may be established in the female germ line and transmitted to the fetus as an integral part of the mutation. This short review summarizes the data collected to date concerning the timing of FMR1 epigenetic gene silencing and reassess the evidence in favor of the theory that gene inactivation takes place by a developmentally regulated process around the 10th week of gestation.
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Affiliation(s)
- Hagar Mor-Shaked
- Stem Cell Research Laboratory, Medical Genetics Institute, Shaare Zedek Medical Center, Jerusalem, Israel.,Hebrew University Medical School, Jerusalem, Israel
| | - Rachel Eiges
- Stem Cell Research Laboratory, Medical Genetics Institute, Shaare Zedek Medical Center, Jerusalem, Israel.,Hebrew University Medical School, Jerusalem, Israel
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18
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Boivin M, Willemsen R, Hukema RK, Sellier C. Potential pathogenic mechanisms underlying Fragile X Tremor Ataxia Syndrome: RAN translation and/or RNA gain-of-function? Eur J Med Genet 2017; 61:674-679. [PMID: 29223504 DOI: 10.1016/j.ejmg.2017.11.001] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2017] [Revised: 09/19/2017] [Accepted: 11/08/2017] [Indexed: 10/18/2022]
Abstract
Fragile X-associated tremor/ataxia syndrome (FXTAS) is an inherited neurodegenerative disease caused by an expansion of 55-200 CGG repeats located in the FMR1 gene. The main clinical and neuropathological features of FXTAS are progressive intention tremor and gait ataxia associated with brain atrophy, neuronal cell loss and presence of ubiquitin-positive intranuclear inclusions in both neurons and astrocytes. At the molecular level, FXTAS is characterized by increased expression of FMR1 sense and antisense RNA containing expanded CGG or GGC repeats, respectively. Here, we discuss the putative molecular mechanisms underlying FXTAS and notably recent reports that expanded CGG and GGC repeats may be pathogenic through RAN translation into toxic proteins.
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Affiliation(s)
- Manon Boivin
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), INSERM U964, CNRS UMR7104, University of Strasbourg, 67400 Illkirch, France
| | - Rob Willemsen
- Department of Clinical Genetics, Erasmus MC, 3015 CN Rotterdam, The Netherlands
| | - Renate K Hukema
- Department of Clinical Genetics, Erasmus MC, 3015 CN Rotterdam, The Netherlands
| | - Chantal Sellier
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), INSERM U964, CNRS UMR7104, University of Strasbourg, 67400 Illkirch, France.
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19
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Dean DD, Agarwal S, Kapoor D, Singh K, Vati C. Molecular Characterization of FMR1 Gene by TP-PCR in Women of Reproductive Age and Women with Premature Ovarian Insufficiency. Mol Diagn Ther 2017; 22:91-100. [PMID: 29188551 DOI: 10.1007/s40291-017-0305-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
BACKGROUND Fragile X syndrome is caused by CGG repeat expansion mutation in the FMR1 gene. Normal alleles have 5-44 CGG repeats with AGG interruptions. The expanded gray zone (GZ) (45-54 repeats) and premutation (PM) (55-200 repeats) alleles are often uninterrupted and are unstably inherited in subsequent generations. The prevalence of PM and GZ carriers is high in the female population, at 1/66 and 1/113, respectively, and PM is associated with fertility problems in 20% of cases. OBJECTIVE Our objective was to molecularly characterize CGG repeats and AGG interruption sequences in the FMR1 gene in women of reproductive age and in women with premature ovarian insufficiency (POI). MATERIALS AND METHODS We conducted molecular analysis of the FMR1 gene from 300 women of reproductive age and 140 women with POI using triplet primed-polymerase chain reaction. This enabled us to identify carriers and to document CGG repeat size and the AGG interruption pattern. RESULTS In women of reproductive age, 1.7% were GZ carriers and 0.3% were PM carriers; in women with POI, 3.6% were GZ carriers and 2.14% were PM carriers. The frequency of GZ and PM carriers did not significantly differ between the cohorts (Fisher's exact test: p < 2.23 for GZ vs. control and p < 0.101 for PM vs. control). Carriers received genetic counselling; family screening identified an additional seven carriers. CONCLUSION We documented preliminary data on the prevalence of GZ and PM carriers among the studied cohorts. The identification of PM carriers among women with POI serves a dual purpose of recognizing a cause for ovarian dysfunction and enabling genetic counselling, which will help carriers when making reproductive decisions.
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Affiliation(s)
- Deepika Delsa Dean
- Department of Genetics, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow, 226014, India
| | - Sarita Agarwal
- Department of Genetics, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow, 226014, India.
| | - Deepa Kapoor
- Department of Obstetrics and Gynecology, General Hospital, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow, 226014, India
| | - Kuldeep Singh
- Department of Pediatrics, AIIMS, Jodhpur, Rajasthan, India
| | - Chandra Vati
- Department of Obstetrics and Gynecology, Krishna Medical Centre, Lucknow, India
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Abstract
Neurodegeneration is a leading cause of death in the developed world and a natural, albeit unfortunate, consequence of longer-lived populations. Despite great demand for therapeutic intervention, it is often the case that these diseases are insufficiently understood at the basic molecular level. What little is known has prompted much hopeful speculation about a generalized mechanistic thread that ties these disparate conditions together at the subcellular level and can be exploited for broad curative benefit. In this review, we discuss a prominent theory supported by genetic and pathological changes in an array of neurodegenerative diseases: that neurons are particularly vulnerable to disruption of RNA-binding protein dosage and dynamics. Here we synthesize the progress made at the clinical, genetic, and biophysical levels and conclude that this perspective offers the most parsimonious explanation for these mysterious diseases. Where appropriate, we highlight the reciprocal benefits of cross-disciplinary collaboration between disease specialists and RNA biologists as we envision a future in which neurodegeneration declines and our understanding of the broad importance of RNA processing deepens.
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Affiliation(s)
- Erin G Conlon
- Department of Biological Sciences, Columbia University, New York, New York 10027, USA
| | - James L Manley
- Department of Biological Sciences, Columbia University, New York, New York 10027, USA
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21
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Man L, Lekovich J, Rosenwaks Z, Gerhardt J. Fragile X-Associated Diminished Ovarian Reserve and Primary Ovarian Insufficiency from Molecular Mechanisms to Clinical Manifestations. Front Mol Neurosci 2017; 10:290. [PMID: 28955201 PMCID: PMC5600956 DOI: 10.3389/fnmol.2017.00290] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2017] [Accepted: 08/28/2017] [Indexed: 12/12/2022] Open
Abstract
Fragile X syndrome (FXS), is caused by a loss-of-function mutation in the FMR1 gene located on the X-chromosome, which leads to the most common cause of inherited intellectual disability in males and the leading single-gene defect associated with autism. A full mutation (FM) is represented by more than 200 CGG repeats within the FMR1 gene, resulting in FXS. A FM is inherited from women carrying a FM or a premutation (PM; 55–200 CGG repeats) allele. PM is associated with phenotypes distinct from those associated with FM. Some manifestations of the PM are unique; fragile-X-associated tremor/ataxia syndrome (FXTAS), and fragile-X-associated primary ovarian insufficiency (FXPOI), while others tend to be non-specific such as intellectual disability. In addition, women carrying a PM may suffer from subfertility or infertility. There is a need to elucidate whether the impairment of ovarian function found in PM carriers arises during the primordial germ cell (PGC) development stage, or due to a rapidly diminishing oocyte pool throughout life or even both. Due to the possibility of expansion into a FM in the next generation, and other ramifications, carrying a PM can have an enormous impact on one’s life; therefore, preconception counseling for couples carrying the PM is of paramount importance. In this review, we will elaborate on the clinical manifestations in female PM carriers and propose the definition of fragile-X-associated diminished ovarian reserve (FXDOR), then we will review recent scientific findings regarding possible mechanisms leading to FXDOR and FXPOI. Lastly, we will discuss counseling, preventative measures and interventions available for women carrying a PM regarding different aspects of their reproductive life, fertility treatment, pregnancy, prenatal testing, contraception and fertility preservation options.
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Affiliation(s)
- Limor Man
- The Ronald O. Perelman and Claudia Cohen Center for Reproductive Medicine, Weill Cornell MedicineNew York, NY, United States
| | - Jovana Lekovich
- The Ronald O. Perelman and Claudia Cohen Center for Reproductive Medicine, Weill Cornell MedicineNew York, NY, United States
| | - Zev Rosenwaks
- The Ronald O. Perelman and Claudia Cohen Center for Reproductive Medicine, Weill Cornell MedicineNew York, NY, United States
| | - Jeannine Gerhardt
- The Ronald O. Perelman and Claudia Cohen Center for Reproductive Medicine, Weill Cornell MedicineNew York, NY, United States
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Pugin A, Faundes V, Santa María L, Curotto B, Aliaga S, Salas I, Soto P, Bravo P, Peña M, Alliende M. Clinical, molecular, and pharmacological aspects of FMR1 -related disorders. NEUROLOGÍA (ENGLISH EDITION) 2017. [DOI: 10.1016/j.nrleng.2014.10.018] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
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23
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Feng W, Chakraborty A. Fragility Extraordinaire: Unsolved Mysteries of Chromosome Fragile Sites. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 1042:489-526. [PMID: 29357071 DOI: 10.1007/978-981-10-6955-0_21] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Chromosome fragile sites are a fascinating cytogenetic phenomenon now widely implicated in a slew of human diseases ranging from neurological disorders to cancer. Yet, the paths leading to these revelations were far from direct, and the number of fragile sites that have been molecularly cloned with known disease-associated genes remains modest. Moreover, as more fragile sites were being discovered, research interests in some of the earliest discovered fragile sites ebbed away, leaving a number of unsolved mysteries in chromosome biology. In this review we attempt to recount some of the early discoveries of fragile sites and highlight those phenomena that have eluded intense scrutiny but remain extremely relevant in our understanding of the mechanisms of chromosome fragility. We then survey the literature for disease association for a comprehensive list of fragile sites. We also review recent studies addressing the underlying cause of chromosome fragility while highlighting some ongoing debates. We report an observed enrichment for R-loop forming sequences in fragile site-associated genes than genomic average. Finally, we will leave the reader with some lingering questions to provoke discussion and inspire further scientific inquiries.
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Affiliation(s)
- Wenyi Feng
- Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, Syracuse, NY, USA.
| | - Arijita Chakraborty
- Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, Syracuse, NY, USA
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Abstract
Fragile X syndrome (FXS) is the first of 3 syndromes identified as a health condition related to fragile X mental retardation (FMR1) gene dysfunction. The other 2 syndromes are fragile X-associated primary ovarian insufficiency syndrome (FXPOI) and fragile X-associated tremor/ataxia syndrome (FXTAS), which together are referred to as fragile X-associated disorders (FXDs). Collectively, this group comprises the 3 faces of fragile X. Even though the 3 conditions share a common genetic defect, each one is a separate health condition that results in a variety of body function impairments such as motor delay, musculoskeletal issues related to low muscle tone, coordination limitations, ataxia, tremor, undefined muscle aches and pains, and, for FXTAS, a late-onset neurodegeneration. Although each FXD condition may benefit from physical therapy intervention, available evidence as to the efficacy of intervention appropriate to FXDs is lacking. This perspective article will discuss the genetic basis of FMR1 gene dysfunction and describe health conditions related to this mutation, which have a range of expressions within a family. Physical therapy concerns and possible assessment and intervention strategies will be introduced. Understanding the intergenerational effect of the FMR1 mutation with potential life-span expression is a key component to identifying and treating the health conditions related to this specific genetic condition.
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Lyons JI, Kerr GR, Mueller PW. Fragile X Syndrome: Scientific Background and Screening Technologies. J Mol Diagn 2015; 17:463-71. [PMID: 26162330 DOI: 10.1016/j.jmoldx.2015.04.006] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2014] [Revised: 03/05/2015] [Accepted: 04/02/2015] [Indexed: 11/26/2022] Open
Abstract
Fragile X is the most common inherited cause of mental retardation with a prevalence of 1 in 4000 for males and 1 in 5000 to 8000 for females. The American College of Medical Genetics and Genomics has recommended diagnostic testing for fragile X in symptomatic persons, women with ovarian dysfunction, and persons with tremor/ataxia syndrome. Although medical and scientific professionals do not currently recommend screening nonsymptomatic populations, improvements in current treatment approaches and ongoing clinical trials have generated growing interest in screening for fragile X. Here, we briefly review the relevant molecular basis of fragile X and fragile X testing and compare three different molecular technologies available for fragile X screening in both males and females. These technologic approaches include destabilizing the CGG-repeat region with betaine and using chimeric CGG-targeted PCR primers, using heat pulses to destabilize C-G bonds in the PCR extension step, and using melting curve analysis to differentiate expanded CGG repeats from normals. The first two-step method performed with high sensitivity and specificity. The second method provided agarose gel images that allow identification of males with expanded CGG repeats and females with expanded CGG-repeat bands which are sometimes faint. The third melting curve analysis method would require controls in each run to correct for shifting optimal cutoff values.
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Affiliation(s)
- Justine I Lyons
- Molecular Risk Assessment Laboratory, Newborn Screening and Molecular Biology Branch, Centers for Disease Control and Prevention, Atlanta, Georgia
| | - Gregory R Kerr
- Molecular Risk Assessment Laboratory, Newborn Screening and Molecular Biology Branch, Centers for Disease Control and Prevention, Atlanta, Georgia
| | - Patricia W Mueller
- Molecular Risk Assessment Laboratory, Newborn Screening and Molecular Biology Branch, Centers for Disease Control and Prevention, Atlanta, Georgia.
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Pugin A, Faundes V, Santa María L, Curotto B, Aliaga S, Salas I, Soto P, Bravo P, Peña MI, Alliende MA. Clinical, molecular, and pharmacological aspects of FMR1 related disorders. Neurologia 2014; 32:241-252. [PMID: 25529181 DOI: 10.1016/j.nrl.2014.10.009] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2014] [Revised: 10/08/2014] [Accepted: 10/23/2014] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND Fragile X syndrome, the most common inherited cause of intellectual disability, is associated with a broad spectrum of disorders across different generations of a single family. This study reviews the clinical manifestations of fragile X-associated disorders as well as the spectrum of mutations of the fragile X mental retardation 1 gene (FMR1) and the neurobiology of the fragile X mental retardation protein (FMRP), and also provides an overview of the potential therapeutic targets and genetic counselling. DEVELOPMENT This disorder is caused by expansion of the CGG repeat (>200 repeats) in the 5 prime untranslated region of FMR1, resulting in a deficit or absence of FMRP. FMRP is an RNA-binding protein that regulates the translation of several genes that are important in synaptic plasticity and dendritic maturation. It is believed that CGG repeat expansions in the premutation range (55 to 200 repeats) elicit an increase in mRNA levels of FMR1, which may cause neuronal toxicity. These changes manifest clinically as developmental problems such as autism and learning disabilities as well as neurodegenerative diseases including fragile X-associated tremor/ataxia syndrome (FXTAS). CONCLUSIONS Advances in identifying the molecular basis of fragile X syndrome may help us understand the causes of neuropsychiatric disorders, and they will probably contribute to development of new and specific treatments.
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Affiliation(s)
- A Pugin
- Laboratorio de Genética y Enfermedades Metabólicas, Instituto de Nutrición y Tecnología de los Alimentos (INTA), Universidad de Chile, Santiago, Chile
| | - V Faundes
- Laboratorio de Genética y Enfermedades Metabólicas, Instituto de Nutrición y Tecnología de los Alimentos (INTA), Universidad de Chile, Santiago, Chile.
| | - L Santa María
- Laboratorio de Genética y Enfermedades Metabólicas, Instituto de Nutrición y Tecnología de los Alimentos (INTA), Universidad de Chile, Santiago, Chile
| | - B Curotto
- Laboratorio de Genética y Enfermedades Metabólicas, Instituto de Nutrición y Tecnología de los Alimentos (INTA), Universidad de Chile, Santiago, Chile
| | - S Aliaga
- Laboratorio de Genética y Enfermedades Metabólicas, Instituto de Nutrición y Tecnología de los Alimentos (INTA), Universidad de Chile, Santiago, Chile
| | - I Salas
- Laboratorio de Genética y Enfermedades Metabólicas, Instituto de Nutrición y Tecnología de los Alimentos (INTA), Universidad de Chile, Santiago, Chile
| | - P Soto
- Laboratorio de Genética y Enfermedades Metabólicas, Instituto de Nutrición y Tecnología de los Alimentos (INTA), Universidad de Chile, Santiago, Chile
| | - P Bravo
- Laboratorio de Genética y Enfermedades Metabólicas, Instituto de Nutrición y Tecnología de los Alimentos (INTA), Universidad de Chile, Santiago, Chile
| | - M I Peña
- Laboratorio de Genética y Enfermedades Metabólicas, Instituto de Nutrición y Tecnología de los Alimentos (INTA), Universidad de Chile, Santiago, Chile
| | - M A Alliende
- Laboratorio de Genética y Enfermedades Metabólicas, Instituto de Nutrición y Tecnología de los Alimentos (INTA), Universidad de Chile, Santiago, Chile
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Sellier C, Usdin K, Pastori C, Peschansky VJ, Tassone F, Charlet-Berguerand N. The multiple molecular facets of fragile X-associated tremor/ataxia syndrome. J Neurodev Disord 2014; 6:23. [PMID: 25161746 PMCID: PMC4144988 DOI: 10.1186/1866-1955-6-23] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/14/2013] [Accepted: 11/15/2013] [Indexed: 02/03/2023] Open
Abstract
Fragile X-associated tremor/ataxia syndrome (FXTAS) is an adult-onset inherited neurodegenerative disorder characterized by intentional tremor, gait ataxia, autonomic dysfunction, and cognitive decline. FXTAS is caused by the presence of a long CGG repeat tract in the 5′ UTR of the FMR1 gene. In contrast to Fragile X syndrome, in which the FMR1 gene harbors over 200 CGG repeats but is transcriptionally silent, the clinical features of FXTAS arise from a toxic gain of function of the elevated levels of FMR1 transcript containing the long CGG tract. However, how this RNA leads to neuronal cell dysfunction is unknown. Here, we discuss the latest advances in the current understanding of the possible molecular basis of FXTAS.
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Affiliation(s)
- Chantal Sellier
- Department of Translational Medicine, IGBMC, INSERM U964 Illkirch, France
| | - Karen Usdin
- Section on Gene Structure and Disease, NIDDK, National Institutes of Health, Bethesda MD 20892, USA
| | - Chiara Pastori
- Department of Psychiatry and Behavioral Sciences and Center for Therapeutic Innovation, Hussman Institute for Human Genomics, University of Miami, Miller School of Medicine, Miami FL 33136, USA
| | - Veronica J Peschansky
- Department of Psychiatry and Behavioral Sciences and Center for Therapeutic Innovation, Hussman Institute for Human Genomics, University of Miami, Miller School of Medicine, Miami FL 33136, USA
| | - Flora Tassone
- Department of Biochemistry and Molecular Medicine, University of California, Davis, School of Medicine, Sacramento CA 95817, USA ; MIND Institute, University of California Davis Medical Center, Sacramento CA 95817, USA
| | - Nicolas Charlet-Berguerand
- Department of Translational Medicine, IGBMC, INSERM U964 Illkirch, France ; Institut de Génétique et de Biologie Moléculaire et Cellulaire, CNRS UMR7104, INSERM U964, University of Strasbourg, 1 rue Laurent Fries, Illkirch F-67404, France
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28
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Berman RF, Buijsen RA, Usdin K, Pintado E, Kooy F, Pretto D, Pessah IN, Nelson DL, Zalewski Z, Charlet-Bergeurand N, Willemsen R, Hukema RK. Mouse models of the fragile X premutation and fragile X-associated tremor/ataxia syndrome. J Neurodev Disord 2014; 6:25. [PMID: 25136376 PMCID: PMC4135345 DOI: 10.1186/1866-1955-6-25] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/22/2013] [Accepted: 01/29/2014] [Indexed: 11/10/2022] Open
Abstract
Carriers of the fragile X premutation (FPM) have CGG trinucleotide repeat expansions of between 55 and 200 in the 5'-UTR of FMR1, compared to a CGG repeat length of between 5 and 54 for the general population. Carriers were once thought to be without symptoms, but it is now recognized that they can develop a variety of early neurological symptoms as well as being at risk for developing the late onset neurodegenerative disorder fragile X-associated tremor/ataxia syndrome (FXTAS). Several mouse models have contributed to our understanding of FPM and FXTAS, and findings from studies using these models are summarized here. This review also discusses how this information is improving our understanding of the molecular and cellular abnormalities that contribute to neurobehavioral features seen in some FPM carriers and in patients with FXTAS. Mouse models show much of the pathology seen in FPM carriers and in individuals with FXTAS, including the presence of elevated levels of Fmr1 mRNA, decreased levels of fragile X mental retardation protein, and ubiquitin-positive intranuclear inclusions. Abnormalities in dendritic spine morphology in several brain regions are associated with neurocognitive deficits in spatial and temporal memory processes, impaired motor performance, and altered anxiety. In vitro studies have identified altered dendritic and synaptic architecture associated with abnormal Ca(2+) dynamics and electrical network activity. FPM mice have been particularly useful in understanding the roles of Fmr1 mRNA, fragile X mental retardation protein, and translation of a potentially toxic polyglycine peptide in pathology. Finally, the potential for using these and emerging mouse models for preclinical development of therapies to improve neurological function in FXTAS is considered.
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Affiliation(s)
- Robert F Berman
- Department of Neurological Surgery, Room 502C, UC Davis, 1515 Newton Court, Davis, CA 95618, USA
| | | | - Karen Usdin
- NIDDK, National Institutes of Health, Bethesda, MD, USA
| | | | - Frank Kooy
- Department of Medical Genetics, University of Antwerp, Antwerp, Belgium
| | | | - Isaac N Pessah
- Department Molecular Biosciences, UC Davis, Davis, CA, USA
| | - David L Nelson
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - Zachary Zalewski
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | | | - Rob Willemsen
- Department Clinical Genetics, Erasmus MC, Rotterdam, Netherlands
| | - Renate K Hukema
- Department Clinical Genetics, Erasmus MC, Rotterdam, Netherlands
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29
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Unconventional features of C9ORF72 expanded repeat in amyotrophic lateral sclerosis and frontotemporal lobar degeneration. Neurobiol Aging 2014; 35:2421.e1-2421.e12. [PMID: 24836899 DOI: 10.1016/j.neurobiolaging.2014.04.015] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2014] [Revised: 03/31/2014] [Accepted: 04/13/2014] [Indexed: 12/12/2022]
Abstract
Amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration (FTLD) are devastating neurodegenerative diseases that form two ends of a complex disease spectrum. Aggregation of RNA binding proteins is one of the hallmark pathologic features of ALS and FTDL and suggests perturbance of the RNA metabolism in their etiology. Recent identification of the disease-associated expansions of the intronic hexanucleotide repeat GGGGCC in the C9ORF72 gene further substantiates the case for RNA involvement. The expanded repeat, which has turned out to be the single most common genetic cause of ALS and FTLD, may enable the formation of complex DNA and RNA structures, changes in RNA transcription, and processing and formation of toxic RNA foci, which may sequester and inactivate RNA binding proteins. Additionally, the transcribed expanded repeat can undergo repeat-associated non-ATG-initiated translation resulting in accumulation of a series of dipeptide repeat proteins. Understanding the basis of the proposed mechanisms and shared pathways, as well as interactions with known key proteins such as TAR DNA-binding protein (TDP-43) are needed to clarify the pathology of ALS and/or FTLD, and make possible steps toward therapy development.
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30
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Favaro F, Alvizi L, Zechi-Ceide R, Bertola D, Felix T, de Souza J, Raskin S, Twigg S, Weiner A, Armas P, Margarit E, Calcaterra N, Andersen G, McGowan S, Wilkie A, Richieri-Costa A, de Almeida M, Passos-Bueno M. A noncoding expansion in EIF4A3 causes Richieri-Costa-Pereira syndrome, a craniofacial disorder associated with limb defects. Am J Hum Genet 2014; 94:120-8. [PMID: 24360810 DOI: 10.1016/j.ajhg.2013.11.020] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2013] [Accepted: 11/22/2013] [Indexed: 01/31/2023] Open
Abstract
Richieri-Costa-Pereira syndrome is an autosomal-recessive acrofacial dysostosis characterized by mandibular median cleft associated with other craniofacial anomalies and severe limb defects. Learning and language disabilities are also prevalent. We mapped the mutated gene to a 122 kb region at 17q25.3 through identity-by-descent analysis in 17 genealogies. Sequencing strategies identified an expansion of a region with several repeats of 18- or 20-nucleotide motifs in the 5' untranslated region (5' UTR) of EIF4A3, which contained from 14 to 16 repeats in the affected individuals and from 3 to 12 repeats in 520 healthy individuals. A missense substitution of a highly conserved residue likely to affect the interaction of eIF4AIII with the UPF3B subunit of the exon junction complex in trans with an expanded allele was found in an unrelated individual with an atypical presentation, thus expanding mutational mechanisms and phenotypic diversity of RCPS. EIF4A3 transcript abundance was reduced in both white blood cells and mesenchymal cells of RCPS-affected individuals as compared to controls. Notably, targeting the orthologous eif4a3 in zebrafish led to underdevelopment of several craniofacial cartilage and bone structures, in agreement with the craniofacial alterations seen in RCPS. Our data thus suggest that RCPS is caused by mutations in EIF4A3 and show that EIF4A3, a gene involved in RNA metabolism, plays a role in mandible, laryngeal, and limb morphogenesis.
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31
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Hagerman R, Hagerman P. Advances in clinical and molecular understanding of the FMR1 premutation and fragile X-associated tremor/ataxia syndrome. Lancet Neurol 2013; 12:786-98. [PMID: 23867198 DOI: 10.1016/s1474-4422(13)70125-x] [Citation(s) in RCA: 238] [Impact Index Per Article: 21.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Fragile X syndrome, the most common heritable form of cognitive impairment, is caused by epigenetic silencing of the fragile X (FMR1) gene owing to large expansions (>200 repeats) of a non-coding CGG-repeat element. Smaller, so-called premutation expansions (55-200 repeats) can cause a family of neurodevelopmental phenotypes (attention deficit hyperactivity disorder, autism spectrum disorder, seizure disorder) and neurodegenerative (fragile X-associated tremor/ataxia syndrome [FXTAS]) phenotypes through an entirely distinct molecular mechanism involving increased FMR1 mRNA production and toxicity. Results of basic cellular, animal, and human studies have helped to elucidate the underlying RNA toxicity mechanism, while clinical research is providing a more nuanced picture of the range of clinical manifestations. Advances of knowledge on both mechanistic and clinical fronts are driving new approaches to targeted treatment, but two important necessities are emerging: to define the extent to which the mechanisms contributing to FXTAS also contribute to other neurodegenerative and medical disorders, and to redefine FXTAS in view of its differing presentations and associated features.
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Affiliation(s)
- Randi Hagerman
- Department of Pediatrics and the MIND Institute, University of California, Davis, School of Medicine, Davis, CA, USA
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32
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Alvarez-Mora MI, Rodriguez-Revenga L, Madrigal I, Torres-Silva F, Mateu-Huertas E, Lizano E, Friedländer MR, Martí E, Estivill X, Milà M. MicroRNA expression profiling in blood from fragile X-associated tremor/ataxia syndrome patients. GENES BRAIN AND BEHAVIOR 2013; 12:595-603. [PMID: 23790110 DOI: 10.1111/gbb.12061] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2013] [Revised: 06/12/2013] [Accepted: 06/21/2013] [Indexed: 01/05/2023]
Abstract
Fragile X-associated tremor/ataxia syndrome (FXTAS) is a late-onset neurodegenerative disorder associated with FMR1 gene premutation alleles (55-200 CGG repeats). Fragile X-associated tremor/ataxia syndrome clinical core features include action tremor, gait ataxia, cognitive deficits progressing to dementia, and frequently parkinsonism. Although the pathogenic molecular mechanism of FXTAS is not completely understood, the restriction of the phenotype to the FMR1 premutation range has given rise to a model based on a RNA toxic gain-of-function. Since the identification of the first microRNAs (miRNAs) and their role in normal development, several studies have associated them with neurodegenerative diseases such as Parkinson, Alzheimer and Huntington diseases, suggesting that they play a key role in brain development, as well as in its morphogenesis. Herein, we present the characterization of miRNA expression profiles in FXTAS male patients using deep sequencing-based technologies and microarray technology. Deep sequencing analysis evidenced 83 miRNAs that were significantly deregulated whereas microarray analysis showed 31. When comparing these results, 14 miRNAs were found deregulated in FXTAS patients. MiR-424 and miR-574-3p showed significant fold change adjusted P-values in both platforms in FXTAS patients. MiR-424 has been founded substantially and specifically enriched in human cerebral cortical white matter of Alzheimer disease patients, which, together with cerebral atrophy, is a prominent imaging finding in individuals with FXTAS. The study provides the first systematic evidence of differential miRNA expression changes in FXTAS blood samples. Although further studies are necessary to better characterize the miRNA function in FXTAS disorder, our results suggest that they might contribute to its pathogenesis.
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Affiliation(s)
- M I Alvarez-Mora
- Biochemistry and Molecular Genetics Department, Hospital Clínic, Barcelona, Spain
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33
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Fragile X-associated tremor/ataxia syndrome (FXTAS): pathology and mechanisms. Acta Neuropathol 2013; 126:1-19. [PMID: 23793382 DOI: 10.1007/s00401-013-1138-1] [Citation(s) in RCA: 104] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2013] [Accepted: 05/30/2013] [Indexed: 12/17/2022]
Abstract
Since its discovery in 2001, our understanding of fragile X-associated tremor/ataxia syndrome (FXTAS) has undergone a remarkable transformation. Initially characterized rather narrowly as an adult-onset movement disorder, the definition of FXTAS is broadening; moreover, the disorder is now recognized as only one facet of a much broader clinical pleiotropy among children and adults who carry premutation alleles of the FMR1 gene. Furthermore, the intranuclear inclusions of FXTAS, once thought to be a CNS-specific marker of the disorder, are now known to be widely distributed in multiple non-CNS tissues; this observation fundamentally changes our concept of the disease, and may provide the basis for understanding the diverse medical problems associated with the premutation. Recent work on the pathogenic mechanisms underlying FXTAS indicates that the origins of the late-onset neurodegenerative disorder actually lie in early development, raising the likelihood that all forms of clinical involvement among premutation carriers have a common underlying mechanistic basis. There has also been great progress in our understanding of the triggering event(s) in FXTAS pathogenesis, which is now thought to involve sequestration of one or more nuclear proteins involved with microRNA biogenesis. Moreover, there is mounting evidence that mitochondrial dysregulation contributes to the decreased cell function and loss of viability, evident in mice even during the neonatal period. Taken together, these recent findings offer hope for early interventions for FXTAS, well before the onset of overt disease, and for the treatment of other forms of clinical involvement among premutation carriers.
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34
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Monaghan KG, Lyon E, Spector EB. ACMG Standards and Guidelines for fragile X testing: a revision to the disease-specific supplements to the Standards and Guidelines for Clinical Genetics Laboratories of the American College of Medical Genetics and Genomics. Genet Med 2013; 15:575-86. [PMID: 23765048 DOI: 10.1038/gim.2013.61] [Citation(s) in RCA: 108] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2013] [Accepted: 04/04/2013] [Indexed: 12/29/2022] Open
Abstract
Molecular genetic testing of the FMR1 gene is commonly performed in clinical laboratories. Mutations in the FMR1 gene are associated with fragile X syndrome, fragile X tremor ataxia syndrome, and premature ovarian insufficiency. This document provides updated information regarding FMR1 gene mutations, including prevalence, genotype-phenotype correlation, and mutation nomenclature. Methodological considerations are provided for Southern blot analysis and polymerase chain reaction amplification of the FMR1 gene, including triplet repeat-primed and methylation-specific polymerase chain reaction. In addition to report elements, examples of laboratory reports for various genotypes are also included.
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Affiliation(s)
- Kristin G Monaghan
- Department of Medical Genetics, Henry Ford Health System, Detroit, Michigan, USA.
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35
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Tsao W, Jeong YH, Lin S, Ling J, Price DL, Chiang PM, Wong PC. Rodent models of TDP-43: recent advances. Brain Res 2012; 1462:26-39. [PMID: 22608070 DOI: 10.1016/j.brainres.2012.04.031] [Citation(s) in RCA: 92] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2012] [Revised: 04/04/2012] [Accepted: 04/17/2012] [Indexed: 12/11/2022]
Abstract
Recently, missense mutations in the gene TARDBP encoding TDP-43 have been linked to familial ALS. The discovery of genes encoding these RNA binding proteins, such as TDP-43 and FUS/TLS, raised the notion that altered RNA metabolism is a major factor underlying the pathogenesis of ALS. To begin to unravel how mutations in TDP-43 cause dysfunction and death of motor neurons, investigators have employed both gain- and loss-of-function studies in rodent model systems. Here, we will summarize major findings from the initial sets of TDP-43 transgenic and knockout rodent models, identify their limitations, and point to future directions toward clarification of disease mechanism(s) and testing of therapeutic strategies that ultimately may lead to novel therapy for this devastating disease. This article is part of a Special Issue entitled RNA-Binding Proteins.
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Affiliation(s)
- William Tsao
- Department of Pathology, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
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36
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DeJesus-Hernandez M, Mackenzie IR, Boeve BF, Boxer AL, Baker M, Rutherford NJ, Nicholson AM, Finch NA, Flynn H, Adamson J, Kouri N, Wojtas A, Sengdy P, Hsiung GYR, Karydas A, Seeley WW, Josephs KA, Coppola G, Geschwind DH, Wszolek ZK, Feldman H, Knopman DS, Petersen RC, Miller BL, Dickson DW, Boylan KB, Graff-Radford NR, Rademakers R. Expanded GGGGCC hexanucleotide repeat in noncoding region of C9ORF72 causes chromosome 9p-linked FTD and ALS. Neuron 2011; 72:245-56. [PMID: 21944778 DOI: 10.1016/j.neuron.2011.09.011] [Citation(s) in RCA: 3653] [Impact Index Per Article: 281.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/14/2011] [Indexed: 12/12/2022]
Abstract
Several families have been reported with autosomal-dominant frontotemporal dementia (FTD) and amyotrophic lateral sclerosis (ALS), genetically linked to chromosome 9p21. Here, we report an expansion of a noncoding GGGGCC hexanucleotide repeat in the gene C9ORF72 that is strongly associated with disease in a large FTD/ALS kindred, previously reported to be conclusively linked to chromosome 9p. This same repeat expansion was identified in the majority of our families with a combined FTD/ALS phenotype and TDP-43-based pathology. Analysis of extended clinical series found the C9ORF72 repeat expansion to be the most common genetic abnormality in both familial FTD (11.7%) and familial ALS (23.5%). The repeat expansion leads to the loss of one alternatively spliced C9ORF72 transcript and to formation of nuclear RNA foci, suggesting multiple disease mechanisms. Our findings indicate that repeat expansion in C9ORF72 is a major cause of both FTD and ALS.
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Abstract
The FMR1 gene contains a CGG repeat present in the 5'-untranslated region which can be unstable upon transmission to the next generation. The repeat is up to 55 CGGs long in the normal population. In patients with fragile X syndrome (FXS), a repeat length exceeding 200 CGGs (full mutation: FM) generally leads to methylation of the repeat and the promoter region, which is accompanied by silencing of the FMR1 gene. The absence of FMR1 protein, FMRP, seen in FM is the cause of the mental retardation in patients with FXS. The premutation (PM) is defined as 55-200 CGGs. Female PM carriers are at risk of developing primary ovarian insufficiency. Elderly PM carriers might develop a progressive neurodegenerative disorder called fragile X-associated tremor/ataxia syndrome (FXTAS). Although arising from the mutations in the same gene, distinct mechanisms lead to FXS (absence of FMRP), FXTAS (toxic RNA gain-of-function) and FXPOI. The pathogenic mechanisms thought to underlie these disorders are discussed. This review gives insight on the implications of all possible repeat length categories seen in fragile X families.
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Affiliation(s)
- R Willemsen
- Department of Clinical Genetics, Erasmus MC, Rotterdam, The Netherlands
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38
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Abstract
An appropriately developed and functional reproductive tract is essential for the natural production of offspring. However, abnormal development or disease, either within or external to the reproductive tract, can cause considerable morbidity and mortality. This Review describes the normal function of each section of the female reproductive tract. Some of the major conditions and diseases that cause reproductive tract dysfunction in women of reproductive age are reviewed, with a focus on endocrine-related dysfunction. As the female reproductive tract is vital for the continuation of the human species, it is crucial to have an improved understanding of how the cells and tissues of this system interact under normal conditions and to define how hormonal and genetic abnormalities cause pathophysiologic derangement of reproduction.
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Affiliation(s)
- Angshumoy Roy
- Department of Pathology, Baylor College of Medicine, Houston, TX 77030, USA
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