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Mbachu CNP, Mbachu II, Hagerman R. A Comprehensive Review of Fragile X Syndrome and Fragile X Premutation Associated Conditions in Africa. Genes (Basel) 2024; 15:683. [PMID: 38927619 PMCID: PMC11203117 DOI: 10.3390/genes15060683] [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: 04/21/2024] [Revised: 05/17/2024] [Accepted: 05/23/2024] [Indexed: 06/28/2024] Open
Abstract
Fragile X syndrome (FXS) is a genetic disorder caused by a mutation in the fragile X messenger ribonucleoprotein 1 (FMR1) gene and known to be a leading cause of inherited intellectual disability globally. It results in a range of intellectual, developmental, and behavioral problems. Fragile X premutation-associated conditions (FXPAC), caused by a smaller CGG expansion (55 to 200 CGG repeats) in the FMR1 gene, are linked to other conditions that increase morbidity and mortality for affected persons. Limited research has been conducted on the burden, characteristics, diagnosis, and management of these conditions in Africa. This comprehensive review provides an overview of the current literature on FXS and FXPAC in Africa. The issues addressed include epidemiology, clinical features, discrimination against affected persons, limited awareness and research, and poor access to resources, including genetic services and treatment programs. This paper provides an in-depth analysis of the existing worldwide data for the diagnosis and treatment of fragile X disorders. This review will improve the understanding of FXS and FXPAC in Africa by incorporating existing knowledge, identifying research gaps, and potential topics for future research to enhance the well-being of individuals and families affected by FXS and FXPAC.
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Affiliation(s)
- Chioma N. P. Mbachu
- Department of Paediatrics, Faculty of Medicine, College of Health Sciences, Nnamdi Azikiwe University, Nnewi Campus, Nnewi 435101, Nigeria
- MIND Institute, University of California Davis, Sacramento, CA 95817, USA
| | - Ikechukwu Innocent Mbachu
- Department of Obstetrics and Gynaecology, Faculty of Medicine, College of Health Sciences, Nnamdi Azikiwe University, Nnewi Campus, Nnewi 435101, Nigeria;
| | - Randi Hagerman
- MIND Institute, University of California Davis, Sacramento, CA 95817, USA
- Department of Pediatrics, University of California Davis Health, Sacramento, CA 95817, USA
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Liu L, Wang H, Xu GL, Liu L. Tet1 Deficiency Leads to Premature Ovarian Failure. Front Cell Dev Biol 2021; 9:644135. [PMID: 33834024 PMCID: PMC8021788 DOI: 10.3389/fcell.2021.644135] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2020] [Accepted: 02/26/2021] [Indexed: 11/13/2022] Open
Abstract
Tet enzymes participate in DNA demethylation and play critical roles in stem cell pluripotency and differentiation. DNA methylation alters with age. We find that Tet1 deficiency reduces fertility and leads to accelerated reproductive failure with age. Noticeably, Tet1-deficient mice at young age exhibit dramatically reduced follicle reserve and the follicle reserve further decreases with age, phenomenon consistent with premature ovarian failure (POF) syndrome. Consequently, Tet1-deficient mice become infertile by reproductive middle age, while age matched wild-type mice still robustly reproduce. Moreover, by single cell transcriptome analysis of oocytes, Tet1 deficiency elevates organelle fission, associated with defects in ubiquitination and declined autophagy, and also upregulates signaling pathways for Alzheimer's diseases, but down-regulates X-chromosome linked genes, such as Fmr1, which is known to be implicated in POF. Additionally, Line1 is aberrantly upregulated and endogenous retroviruses also are altered in Tet1-deficient oocytes. These molecular changes are consistent with oocyte senescence and follicle atresia and depletion found in premature ovarian failure or insufficiency. Our data suggest that Tet1 enzyme plays roles in maintaining oocyte quality as well as oocyte number and follicle reserve and its deficiency can lead to POF.
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Affiliation(s)
- Linlin Liu
- Department of Cell Biology and Genetics, College of Life Sciences, Nankai University, Tianjin, China.,State Key Laboratory of Medicinal Chemical Biology, Nankai University, Tianjin, China
| | - Huasong Wang
- Department of Cell Biology and Genetics, College of Life Sciences, Nankai University, Tianjin, China.,State Key Laboratory of Medicinal Chemical Biology, Nankai University, Tianjin, China
| | - Guo Liang Xu
- State Key Laboratory of Molecular Biology, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, Shanghai, China.,Key Laboratory of Medical Epigenetics and Metabolism, Institutes of Biomedical Sciences, Medical College of Fudan University, Shanghai, China
| | - Lin Liu
- Department of Cell Biology and Genetics, College of Life Sciences, Nankai University, Tianjin, China.,State Key Laboratory of Medicinal Chemical Biology, Nankai University, Tianjin, China
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Premature ovarian insufficiency: clinical orientations for genetic testing and genetic counseling. Porto Biomed J 2020; 5:e62. [PMID: 33299945 PMCID: PMC7722400 DOI: 10.1097/j.pbj.0000000000000062] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2020] [Accepted: 03/29/2020] [Indexed: 02/07/2023] Open
Abstract
Premature ovarian insufficiency (POI) is a heterogeneous disorder diagnosed in women before 40 years old and describes a wide range of impaired ovarian function, from diminished ovarian reserve to premature ovarian failure. Genetic etiology accounts for 20% to 25% of patients. The evidence that POI can be isolated (nonsyndromic) or part of a pleiotropic genetic syndrome highlights its high heterogeneous etiology. Chromosomal abnormalities as a cause of POI have a prevalence of 10% to 13%, being 45,X complement the most common cytogenetic cause of primary amenorrhea and mosaicism with a 45,X cell line more frequently associated with secondary amenorrhea. Other X chromosome aberrations include deletions, duplications, balanced, and unbalanced X-autosome rearrangements involving the critical region for the POI phenotype (Xq13-Xq21 to Xq23-Xq27). The identification of 2 or more pathogenic variants in distinct genes argues in favor of a polygenic origin for POI. Hundreds of pathogenic variants (including mitochondrial) have been involved in POI etiology mainly with key roles in biological processes in the ovary, such as meiosis and DNA damage repair mechanism, homologous recombination, follicular development, granulosa cell differentiation and proliferation, and ovulation. The most common single gene cause for POI is the premutation for FMR1 gene (associated with fragile X syndrome) with alleles ranging from about 55 to about 200 CGG trinucleotide repeats. POI occurs in 20% of women with this premutation. As females with premutation or full mutation alleles are also at risk of having affected children, their genetic counseling should include the indication for prenatal diagnosis or preimplantation genetic testing after intracytoplasmic sperm injection and trophectoderm biopsy. In conclusion, in clinical practice high-resolution karyotype and FMR1 gene molecular study should be performed as first-tier tests in the assessment of POI. In addition, array Comparative Genomic Hybridization or specific next generation sequencing panels should be considered to identify chromosomal deletions/duplications under karyotype resolution or other pathogenic variants in specific genes associated with POI. This is particularly important in patients with first- or second-degree relatives also affected with POI, improving their reproductive and genetic counseling.
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Bouali N, Francou B, Bouligand J, Imanci D, Dimassi S, Tosca L, Zaouali M, Mougou S, Young J, Saad A, Guiochon-Mantel A. New MCM8 mutation associated with premature ovarian insufficiency and chromosomal instability in a highly consanguineous Tunisian family. Fertil Steril 2017; 108:694-702. [PMID: 28863940 DOI: 10.1016/j.fertnstert.2017.07.015] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2017] [Revised: 06/22/2017] [Accepted: 07/14/2017] [Indexed: 01/22/2023]
Abstract
OBJECTIVE To identify the gene(s) involved in the etiology of premature ovarian insufficiency in a highly consanguineous Tunisian family. DESIGN Genetic analysis of a large consanguineous family with several affected siblings. SETTING University hospital-based cytogenetics and molecular genetics laboratories. PATIENT(S) A highly consanguineous Tunisian family with several affected siblings born to healthy second-degree cousins. INTERVENTION(S) None. MAIN OUTCOME MEASURE(S) Targeted exome sequencing was performed by next-generation sequencing for affected family members. Mutations were validated by Sanger sequencing. Functional experiments were performed to explore the deleterious effects of the identified mutation. DNA damage was induced by increasing mitomycin C (MMC) concentrations on cultured peripheral lymphocytes. RESULT(S) Analysis of the next-generation sequencing data revealed a new homozygous missense mutation in the minichromosome maintenance 8 gene (MCM8).This homozygous mutation (c. 482A>C; p.His161Pro) was predicted to be deleterious and segregated with the disease in the family. MCM8 participates in homologous recombination during meiosis and DNA double-stranded break repair by dimerizing with MCM9. Mcm8 knock out results in an early block in follicle development and small gonads. Given this, we tested the chromosomal breakage repair capacity of homozygous and heterozygous MCM8 p.His161Pro mutation on cultured peripheral lymphocytes exposed to increasing MMC concentrations. We found that chromosomal breakage after MMC exposure was significantly higher in cells from homozygously affected individuals than in those from a healthy control. CONCLUSION(S) Our findings provide additional support to the view that MCM8 mutations are involved in the primary ovarian insufficiency phenotype.
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Affiliation(s)
- Nouha Bouali
- Laboratory of Human Cytogenetics, Molecular Genetics and Reproductive Biology, Farhat Hached University Hospital, Sousse, Tunisia.
| | - Bruno Francou
- Inserm UMRS_1185, Faculté de Médecine Paris Sud, Université Paris-Sud, Université Paris Saclay, Le Kremlin-Bicêtre, France; Service de Génétique Moléculaire, Pharmacogénétique et Hormonologie, Hôpital Bicêtre, Assistance publique-Hôpitaux de Paris, Le Kremlin-Bicêtre, France
| | - Jérôme Bouligand
- Inserm UMRS_1185, Faculté de Médecine Paris Sud, Université Paris-Sud, Université Paris Saclay, Le Kremlin-Bicêtre, France; Service de Génétique Moléculaire, Pharmacogénétique et Hormonologie, Hôpital Bicêtre, Assistance publique-Hôpitaux de Paris, Le Kremlin-Bicêtre, France
| | - Dilek Imanci
- Service de Génétique Moléculaire, Pharmacogénétique et Hormonologie, Hôpital Bicêtre, Assistance publique-Hôpitaux de Paris, Le Kremlin-Bicêtre, France
| | - Sarra Dimassi
- Laboratory of Human Cytogenetics, Molecular Genetics and Reproductive Biology, Farhat Hached University Hospital, Sousse, Tunisia
| | - Lucie Tosca
- Service d'Histologie, Embryologie et Cytogénétique, Hôpital Antoine-Béclère, Clamart, France
| | - Monia Zaouali
- Department of Physiology and Functional Exploration, Farhat Hached University Hospital, Sousse, Tunisia
| | - Soumaya Mougou
- Laboratory of Human Cytogenetics, Molecular Genetics and Reproductive Biology, Farhat Hached University Hospital, Sousse, Tunisia
| | - Jacques Young
- Inserm UMRS_1185, Faculté de Médecine Paris Sud, Université Paris-Sud, Université Paris Saclay, Le Kremlin-Bicêtre, France; Service d'Endocrinologie et des maladies de la Reproduction, Hôpital Bicêtre, Assistance publique-Hôpitaux de Paris, Le Kremlin-Bicêtre, France
| | - Ali Saad
- Laboratory of Human Cytogenetics, Molecular Genetics and Reproductive Biology, Farhat Hached University Hospital, Sousse, Tunisia
| | - Anne Guiochon-Mantel
- Inserm UMRS_1185, Faculté de Médecine Paris Sud, Université Paris-Sud, Université Paris Saclay, Le Kremlin-Bicêtre, France; Service de Génétique Moléculaire, Pharmacogénétique et Hormonologie, Hôpital Bicêtre, Assistance publique-Hôpitaux de Paris, Le Kremlin-Bicêtre, France
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Bouali N, Francou B, Bouligand J, Lakhal B, Malek I, Kammoun M, Warszawski J, Mougou S, Saad A, Guiochon-Mantel A. NOBOX is a strong autosomal candidate gene in Tunisian patients with primary ovarian insufficiency. Clin Genet 2016; 89:608-13. [PMID: 26848058 DOI: 10.1111/cge.12750] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2015] [Revised: 01/27/2016] [Accepted: 01/27/2016] [Indexed: 12/13/2022]
Abstract
Premature ovarian insufficiency (POI) affects approximately 1% of women before the age of 40. Genetic contribution is a significant component of POI. In this context, heterozygous mutations in NOBOX, BMP15 and GDF9 have been reported. The objective of our study was to evaluate the prevalence of these genes mutations in 125 unrelated Tunisian patients diagnosed with POI. The screening of NOBOX gene revealed three missense mutations (p.Arg117Trp; p.Gly91Trp and p.Pro619Leu) in eight patients. These mutations were not found in a 200 ethnically matched women without fertility problem. The sequencing of BMP15 and GDF9 gene revealed only previously reported variants. In contrast to previous studies, the prevalence of BMP15 variations is not higher than in the control population. Conversely, 6.4% of the cases present a NOBOX mutations; this high prevalence strengthens the consideration of NOBOX gene as strong autosomal candidate for POI.
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Affiliation(s)
- N Bouali
- Laboratory of Human Cytogenetics, Molecular Genetics and Reproductive Biology, Farhat Hached University Hospital, Sousse, 4000, Tunisia
| | - B Francou
- Faculté de Médecine Paris Sud, INSERM UMR_S1185, University Paris Saclay, Univ Paris sud, Le Kremlin-Bicêtre, France.,Assistance Publique-Hôpitaux de Paris, Hôpital Bicêtre, Service de Génétique moléculaire, Pharmacogénétique et Hormonologie, Le Kremlin-Bicêtre, France
| | - J Bouligand
- Faculté de Médecine Paris Sud, INSERM UMR_S1185, University Paris Saclay, Univ Paris sud, Le Kremlin-Bicêtre, France.,Assistance Publique-Hôpitaux de Paris, Hôpital Bicêtre, Service de Génétique moléculaire, Pharmacogénétique et Hormonologie, Le Kremlin-Bicêtre, France
| | - B Lakhal
- Laboratory of Human Cytogenetics, Molecular Genetics and Reproductive Biology, Farhat Hached University Hospital, Sousse, 4000, Tunisia
| | - I Malek
- Laboratory of Human Cytogenetics, Molecular Genetics and Reproductive Biology, Farhat Hached University Hospital, Sousse, 4000, Tunisia
| | - M Kammoun
- Laboratory of Human Cytogenetics, Molecular Genetics and Reproductive Biology, Farhat Hached University Hospital, Sousse, 4000, Tunisia
| | - J Warszawski
- Assistance Publique-Hôpitaux de Paris, Hôpital Bicêtre, Service d'Epidémiologie, University Paris Saclay, University Paris-Sud, INSERM U1018 eq 4, Le Kremlin-Bicêtre, France
| | - S Mougou
- Laboratory of Human Cytogenetics, Molecular Genetics and Reproductive Biology, Farhat Hached University Hospital, Sousse, 4000, Tunisia
| | - A Saad
- Laboratory of Human Cytogenetics, Molecular Genetics and Reproductive Biology, Farhat Hached University Hospital, Sousse, 4000, Tunisia
| | - A Guiochon-Mantel
- Faculté de Médecine Paris Sud, INSERM UMR_S1185, University Paris Saclay, Univ Paris sud, Le Kremlin-Bicêtre, France.,Assistance Publique-Hôpitaux de Paris, Hôpital Bicêtre, Service de Génétique moléculaire, Pharmacogénétique et Hormonologie, Le Kremlin-Bicêtre, France
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