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Řeboun M, Sikora J, Magner M, Wiederlechnerová H, Černá A, Poupětová H, Štorkánova G, Mušálková D, Dostálová G, Goláň L, Linhart A, Dvořáková L. Pitfalls of X-chromosome inactivation testing in females with Fabry disease. Am J Med Genet A 2022; 188:1979-1989. [PMID: 35338595 DOI: 10.1002/ajmg.a.62728] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2021] [Revised: 02/09/2022] [Accepted: 03/04/2022] [Indexed: 11/07/2022]
Abstract
Fabry disease (FD) is an X-linked lysosomal storage disorder caused by mutations in the GLA gene encoding alpha-galactosidase A (AGAL). The impact of X-chromosome inactivation (XCI) on the phenotype of female FD patients remains unclear. In this study we aimed to determine pitfalls of XCI testing in a cohort of 35 female FD patients. XCI was assessed by two methylation-based and two allele-specific expression assays. The results correlated, although some variance among the four assays was observed. GLA transcript analyses identified crossing-over in three patients and detected mRNA instability in three out of four analyzed null alleles. AGAL activity correlated with XCI pattern and was not influenced by the mutation type or by reduced mRNA stability. Therefore, AGAL activity may help to detect crossing-over in patients with unstable GLA alleles. Tissue-specific XCI patterns in six patients, and age-related changes in two patients were observed. To avoid misinterpretation of XCI results in female FD patients we show that (i) a combination of several XCI assays generates more reliable results and minimizes possible biases; (ii) correlating XCI to GLA expression and AGAL activity facilitates identification of cross-over events; (iii) age- and tissue-related XCI specificities of XCI patterning should be considered.
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Affiliation(s)
- Martin Řeboun
- Diagnostic laboratories of IMD, Department of Pediatrics and Inherited Metabolic Disorders, First Faculty of Medicine, Charles University and General University Hospital, Prague, Czech Republic
| | - Jakub Sikora
- Research Unit for Rare Diseases, Department of Pediatrics and Inherited Metabolic Disorders, First Faculty of Medicine, Charles University and General University Hospital, Prague, Czech Republic.,Institute of Pathology, First Faculty of Medicine, Charles University and General University Hospital, Prague, Czech Republic
| | - Martin Magner
- Diagnostic laboratories of IMD, Department of Pediatrics and Inherited Metabolic Disorders, First Faculty of Medicine, Charles University and General University Hospital, Prague, Czech Republic.,Department of Pediatrics, Thomayer University Hospital and First Faculty of Medicine, Charles University, Prague, Czech Republic
| | - Helena Wiederlechnerová
- Diagnostic laboratories of IMD, Department of Pediatrics and Inherited Metabolic Disorders, First Faculty of Medicine, Charles University and General University Hospital, Prague, Czech Republic
| | - Alena Černá
- Diagnostic laboratories of IMD, Department of Pediatrics and Inherited Metabolic Disorders, First Faculty of Medicine, Charles University and General University Hospital, Prague, Czech Republic
| | - Helena Poupětová
- Diagnostic laboratories of IMD, Department of Pediatrics and Inherited Metabolic Disorders, First Faculty of Medicine, Charles University and General University Hospital, Prague, Czech Republic
| | - Gabriela Štorkánova
- Diagnostic laboratories of IMD, Department of Pediatrics and Inherited Metabolic Disorders, First Faculty of Medicine, Charles University and General University Hospital, Prague, Czech Republic
| | - Dita Mušálková
- Research Unit for Rare Diseases, Department of Pediatrics and Inherited Metabolic Disorders, First Faculty of Medicine, Charles University and General University Hospital, Prague, Czech Republic
| | - Gabriela Dostálová
- Second Department of Internal Cardiovascular Medicine, First Faculty of Medicine, Charles University and General University Hospital, Prague, Czech Republic
| | - Lubor Goláň
- Second Department of Internal Cardiovascular Medicine, First Faculty of Medicine, Charles University and General University Hospital, Prague, Czech Republic
| | - Aleš Linhart
- Second Department of Internal Cardiovascular Medicine, First Faculty of Medicine, Charles University and General University Hospital, Prague, Czech Republic
| | - Lenka Dvořáková
- Diagnostic laboratories of IMD, Department of Pediatrics and Inherited Metabolic Disorders, First Faculty of Medicine, Charles University and General University Hospital, Prague, Czech Republic
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Rodrigues B, Gonçalves A, Sousa V, Maia N, Marques I, Vale-Fernandes E, Santos R, Nogueira AJA, Jorge P. Use of the FMR1 Gene Methylation Status to Assess the X-Chromosome Inactivation Pattern: A Stepwise Analysis. Genes (Basel) 2022; 13:419. [PMID: 35327973 PMCID: PMC8951761 DOI: 10.3390/genes13030419] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Revised: 02/22/2022] [Accepted: 02/23/2022] [Indexed: 11/23/2022] Open
Abstract
X-chromosome inactivation (XCI) is a developmental process to compensate the imbalance in the dosage of X-chromosomal genes in females. A skewing of the XCI pattern may suggest a carrier status for an X-linked disease or explain the presence of a severe phenotype. In these cases, it is important to determine the XCI pattern, conventionally using the gold standard Human Androgen-Receptor Assay (HUMARA), based on the analysis of the methylation status at a polymorphic CAG region in the first exon of the human androgen receptor gene (AR). The aim of this study was to evaluate whether the methylation status of the fragile mental retardation protein translational regulator gene (FMR1) can provide an XCI pattern similar to that obtained by HUMARA. A set of 48 female carriers of FMR1 gene normal-sized alleles was examined using two assays: HUMARA and a FMR1 methylation PCR (mPCR). Ranges were defined to establish the XCI pattern using the methylation pattern of the FMR1 gene by mPCR. Overall, a 77% concordance of the XCI patterns was obtained between the two assays, which led us to propose a set of key points and a stepwise analysis towards obtaining an accurate result for the XCI pattern and to minimize the underlying pitfalls.
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Affiliation(s)
- Bárbara Rodrigues
- Molecular Genetics Unit, Centro de Genética Médica Dr. Jacinto Magalhães (CGM), Centro Hospitalar Universitário do Porto (CHUPorto), 4099-028 Porto, Portugal; (B.R.); (A.G.); (V.S.); (N.M.); (I.M.); (R.S.)
- UMIB—Unit for Multidisciplinary Research in Biomedicine, ICBAS—School of Medicine and Biomedical Sciences, University of Porto, 4050-313 Porto, Portugal;
- ITR—Laboratory for Integrative and Translational Research in Population Health, 4050-313 Porto, Portugal
| | - Ana Gonçalves
- Molecular Genetics Unit, Centro de Genética Médica Dr. Jacinto Magalhães (CGM), Centro Hospitalar Universitário do Porto (CHUPorto), 4099-028 Porto, Portugal; (B.R.); (A.G.); (V.S.); (N.M.); (I.M.); (R.S.)
- UMIB—Unit for Multidisciplinary Research in Biomedicine, ICBAS—School of Medicine and Biomedical Sciences, University of Porto, 4050-313 Porto, Portugal;
- ITR—Laboratory for Integrative and Translational Research in Population Health, 4050-313 Porto, Portugal
| | - Vanessa Sousa
- Molecular Genetics Unit, Centro de Genética Médica Dr. Jacinto Magalhães (CGM), Centro Hospitalar Universitário do Porto (CHUPorto), 4099-028 Porto, Portugal; (B.R.); (A.G.); (V.S.); (N.M.); (I.M.); (R.S.)
| | - Nuno Maia
- Molecular Genetics Unit, Centro de Genética Médica Dr. Jacinto Magalhães (CGM), Centro Hospitalar Universitário do Porto (CHUPorto), 4099-028 Porto, Portugal; (B.R.); (A.G.); (V.S.); (N.M.); (I.M.); (R.S.)
- UMIB—Unit for Multidisciplinary Research in Biomedicine, ICBAS—School of Medicine and Biomedical Sciences, University of Porto, 4050-313 Porto, Portugal;
- ITR—Laboratory for Integrative and Translational Research in Population Health, 4050-313 Porto, Portugal
| | - Isabel Marques
- Molecular Genetics Unit, Centro de Genética Médica Dr. Jacinto Magalhães (CGM), Centro Hospitalar Universitário do Porto (CHUPorto), 4099-028 Porto, Portugal; (B.R.); (A.G.); (V.S.); (N.M.); (I.M.); (R.S.)
- UMIB—Unit for Multidisciplinary Research in Biomedicine, ICBAS—School of Medicine and Biomedical Sciences, University of Porto, 4050-313 Porto, Portugal;
- ITR—Laboratory for Integrative and Translational Research in Population Health, 4050-313 Porto, Portugal
| | - Emídio Vale-Fernandes
- UMIB—Unit for Multidisciplinary Research in Biomedicine, ICBAS—School of Medicine and Biomedical Sciences, University of Porto, 4050-313 Porto, Portugal;
- ITR—Laboratory for Integrative and Translational Research in Population Health, 4050-313 Porto, Portugal
- Centre for Medically Assisted Procreation/Public Gamete Bank, Centro Materno-Infantil do Norte Dr. Albino Aroso (CMIN), Centro Hospitalar Universitário do Porto (CHUPorto), 4050-651 Porto, Portugal
| | - Rosário Santos
- Molecular Genetics Unit, Centro de Genética Médica Dr. Jacinto Magalhães (CGM), Centro Hospitalar Universitário do Porto (CHUPorto), 4099-028 Porto, Portugal; (B.R.); (A.G.); (V.S.); (N.M.); (I.M.); (R.S.)
- UMIB—Unit for Multidisciplinary Research in Biomedicine, ICBAS—School of Medicine and Biomedical Sciences, University of Porto, 4050-313 Porto, Portugal;
- ITR—Laboratory for Integrative and Translational Research in Population Health, 4050-313 Porto, Portugal
| | - António J. A. Nogueira
- CESAM—Center for Environmental and Marine Studies, Department of Biology, University of Aveiro, 3810-193 Aveiro, Portugal;
| | - Paula Jorge
- Molecular Genetics Unit, Centro de Genética Médica Dr. Jacinto Magalhães (CGM), Centro Hospitalar Universitário do Porto (CHUPorto), 4099-028 Porto, Portugal; (B.R.); (A.G.); (V.S.); (N.M.); (I.M.); (R.S.)
- UMIB—Unit for Multidisciplinary Research in Biomedicine, ICBAS—School of Medicine and Biomedical Sciences, University of Porto, 4050-313 Porto, Portugal;
- ITR—Laboratory for Integrative and Translational Research in Population Health, 4050-313 Porto, Portugal
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Cho RY, Peñaherrera MS, Du Souich C, Huang L, Mwenifumbo J, Nelson TN, Elliott AM, Adam S, Eydoux P, Yang GX, Chijiwa C, Van Allen MI, Friedman JM, Robinson WP, Lehman A. Renpenning syndrome in a female. Am J Med Genet A 2019; 182:498-503. [PMID: 31840929 DOI: 10.1002/ajmg.a.61451] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2019] [Revised: 10/26/2019] [Accepted: 10/29/2019] [Indexed: 01/03/2023]
Abstract
Renpenning syndrome (OMIM: 309500) is a rare X-linked disorder that causes intellectual disability, microcephaly, short stature, a variety of eye anomalies, and characteristic craniofacial features. This condition results from pathogenic variation of PQBP1, a polyglutamine-binding protein involved in transcription and pre-mRNA splicing. Renpenning syndrome has only been reported in affected males. Carrier females do not usually have clinical features, and in reported families with Renpenning syndrome, most female carriers exhibit favorable skewing of X-chromosome inactivation. We describe a female with syndromic features typical of Renpenning syndrome. She was identified by exome sequencing to have a de novo heterozygous c.459_462delAGAG mutation in PQBP1 (Xp11.23), affecting the AG hexamer in exon 4, which is the most common causative mutation in this syndrome. Streaky hypopigmentation of the skin was observed, supporting a hypothesized presence of an actively expressed, PQBP1 mutation-bearing X-chromosome in some cells. X-inactivation studies on peripheral blood cells demonstrated complete skewing in both the proband and her mother with preferential inactivation of the maternal X chromosome in the child. We demonstrated expression of the PQBP1 mutant transcript in leukocytes of the affected girl. Therefore, it is highly likely that the PQBP1 mutation arose from the paternal X chromosome.
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Affiliation(s)
- Raymond Y Cho
- Department of Medical Genetics, University of British Columbia, Vancouver, British Columbia, Canada
| | - Maria S Peñaherrera
- Department of Medical Genetics, University of British Columbia, Vancouver, British Columbia, Canada.,BC Children's Hospital Research Institute, Vancouver, British Columbia, Canada
| | - Christele Du Souich
- Department of Medical Genetics, University of British Columbia, Vancouver, British Columbia, Canada.,BC Children's Hospital Research Institute, Vancouver, British Columbia, Canada
| | - Lijia Huang
- Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, British Columbia, Canada
| | - Jill Mwenifumbo
- Department of Medical Genetics, University of British Columbia, Vancouver, British Columbia, Canada
| | - Tanya N Nelson
- Department of Medical Genetics, University of British Columbia, Vancouver, British Columbia, Canada.,Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, British Columbia, Canada.,BC Children's Hospital Research Institute, Vancouver, British Columbia, Canada
| | - Alison M Elliott
- Department of Medical Genetics, University of British Columbia, Vancouver, British Columbia, Canada
| | - Shelin Adam
- Department of Medical Genetics, University of British Columbia, Vancouver, British Columbia, Canada
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- Department of Medical Genetics, University of British Columbia, Vancouver, British Columbia, Canada
| | - Patrice Eydoux
- Department of Medical Genetics, University of British Columbia, Vancouver, British Columbia, Canada.,Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, British Columbia, Canada.,BC Children's Hospital Research Institute, Vancouver, British Columbia, Canada
| | - Gui X Yang
- Department of Medical Genetics, University of British Columbia, Vancouver, British Columbia, Canada
| | - Chieko Chijiwa
- Department of Medical Genetics, University of British Columbia, Vancouver, British Columbia, Canada
| | - Margot I Van Allen
- Department of Medical Genetics, University of British Columbia, Vancouver, British Columbia, Canada.,BC Children's Hospital Research Institute, Vancouver, British Columbia, Canada
| | - Jan M Friedman
- Department of Medical Genetics, University of British Columbia, Vancouver, British Columbia, Canada.,BC Children's Hospital Research Institute, Vancouver, British Columbia, Canada
| | - Wendy P Robinson
- Department of Medical Genetics, University of British Columbia, Vancouver, British Columbia, Canada.,BC Children's Hospital Research Institute, Vancouver, British Columbia, Canada
| | - Anna Lehman
- Department of Medical Genetics, University of British Columbia, Vancouver, British Columbia, Canada.,BC Children's Hospital Research Institute, Vancouver, British Columbia, Canada
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Zikánová M, Wahezi D, Hay A, Stiburková B, Pitts C, Mušálková D, Škopová V, Barešová V, Soucková O, Hodanová K, Živná M, Stránecký V, Hartmannová H, Hnízda A, Bleyer AJ, Kmoch S. Clinical manifestations and molecular aspects of phosphoribosylpyrophosphate synthetase superactivity in females. Rheumatology (Oxford) 2019; 57:1180-1185. [PMID: 30423175 DOI: 10.1093/rheumatology/key041] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2017] [Indexed: 01/28/2023] Open
Abstract
Objectives Phosphoribosylpyrophosphate synthetase (PRPS1) superactivity is an X-linked disorder characterized by urate overproduction Online Mendelian Inheritance in Man (OMIM) gene reference 300661. This condition is thought to rarely affect women, and when it does, the clinical presentation is mild. We describe a 16-year-old African American female who developed progressive tophi, nephrolithiasis and acute kidney failure due to urate overproduction. Family history included a mother with tophaceous gout who developed end-stage kidney disease due to nephrolithiasis and an affected sister with polyarticular gout. The main aim of this study was to describe the clinical manifestations of PRPS1 superactivity in women. Methods Whole exome sequencing was performed in affected females and their fathers. Results Mutational analysis revealed a new c.520 G > A (p.G174R) mutation in the PRPS1 gene. The mutation resulted in decreased PRPS1 inhibition by ADP. Conclusion Clinical findings in previously reported females with PRPS1 superactivity showed a high clinical penetrance of this disorder with a mean serum urate level of 8.5 (4.1) mg/dl [506 (247) μmol/l] and a high prevalence of gout. These findings indicate that all women in families with PRPS1 superactivity should be genetically screened for a mutation (for clinical management and genetic counselling). In addition, women with tophaceous gout, gout presenting in childhood, or a strong family history of severe gout should be considered for PRPS1 mutational analysis.
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Affiliation(s)
- Marie Zikánová
- Institute of Inherited Metabolic Disorders, First Faculty of Medicine, Charles University, Prague, Czech Republic
| | - Dawn Wahezi
- Pediatric Rheumatology, Children's Hospital at Montefiore, Bronx, NY, USA
| | - Arielle Hay
- Pediatric Rheumatology, Nicklaus Children's Hospital, Miami, FL, USA
| | - Blanka Stiburková
- Institute of Inherited Metabolic Disorders, First Faculty of Medicine, Charles University, Prague, Czech Republic.,Institute of Rheumatology, Prague, Czech Republic
| | - Charles Pitts
- Section on Nephrology, Wake Forest School of Medicine, Winston-Salem, NC
| | - Dita Mušálková
- Institute of Inherited Metabolic Disorders, First Faculty of Medicine, Charles University, Prague, Czech Republic
| | - Václava Škopová
- Institute of Inherited Metabolic Disorders, First Faculty of Medicine, Charles University, Prague, Czech Republic
| | - Veronika Barešová
- Institute of Inherited Metabolic Disorders, First Faculty of Medicine, Charles University, Prague, Czech Republic
| | - Olga Soucková
- Institute of Inherited Metabolic Disorders, First Faculty of Medicine, Charles University, Prague, Czech Republic
| | - Katerina Hodanová
- Institute of Inherited Metabolic Disorders, First Faculty of Medicine, Charles University, Prague, Czech Republic
| | - Martina Živná
- Institute of Inherited Metabolic Disorders, First Faculty of Medicine, Charles University, Prague, Czech Republic
| | - Viktor Stránecký
- Institute of Inherited Metabolic Disorders, First Faculty of Medicine, Charles University, Prague, Czech Republic
| | - Hana Hartmannová
- Institute of Inherited Metabolic Disorders, First Faculty of Medicine, Charles University, Prague, Czech Republic
| | - Ales Hnízda
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Prague, Czech Republic
| | - Anthony J Bleyer
- Institute of Inherited Metabolic Disorders, First Faculty of Medicine, Charles University, Prague, Czech Republic.,Section on Nephrology, Wake Forest School of Medicine, Winston-Salem, NC
| | - Stanislav Kmoch
- Institute of Inherited Metabolic Disorders, First Faculty of Medicine, Charles University, Prague, Czech Republic.,Section on Nephrology, Wake Forest School of Medicine, Winston-Salem, NC
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Michaud V, Defoort-Dhellemmes S, Drumare I, Pennamen P, Plaisant C, Lasseaux E, Arveiler B. Clinical and molecular findings of FRMD7 related congenital nystagmus as adifferential diagnosis of ocular albinism. Ophthalmic Genet 2019; 40:161-164. [PMID: 30942644 DOI: 10.1080/13816810.2019.1592201] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
BACKGROUND Congenital nystagmus is one of the most common neuro-ophthalmological disorders. X chromosome-linked forms are associated with pathogenic variants of the GPR143 and FRMD7 genes. MATERIALS AND METHODS Patients' DNA was analyzed using a next-generation sequencing (NGS) panel of genes involved in albinism and related pathologies (TYR, OCA2, TYRP1, SLC45A2, SLC24A5, C10ORF11, GPR143, SLC38A8, HPS 1 to 10, LYST, MITF, FRMD7) Results: We report a 4 generation family with 5 affected members initially referred for molecular diagnosis of ocular albinism. A missense variant of FRMD7 was found in 3 affected cases and one female carrier. We show that the disease in the affected girl is due to skewed inactivation of the X chromosome. CONCLUSIONS By compiling all the published cases we discuss the variable penetrance among females due to different types of mutation and to X-inactivation.
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Affiliation(s)
- Vincent Michaud
- a Service de Génétique Médicale , CHU de Bordeaux , Bordeaux , France
| | | | - Isabelle Drumare
- b Service d'exploration de la vision et neuro-ophtalmologie , CHRU de Lille , Lille , France
| | - Perrine Pennamen
- a Service de Génétique Médicale , CHU de Bordeaux , Bordeaux , France.,c INSERM U1211, Maladies Rares, Génétique et Métabolisme , Université de Bordeaux , Bordeaux , France
| | - Claudio Plaisant
- a Service de Génétique Médicale , CHU de Bordeaux , Bordeaux , France
| | - Eulalie Lasseaux
- a Service de Génétique Médicale , CHU de Bordeaux , Bordeaux , France
| | - Benoit Arveiler
- a Service de Génétique Médicale , CHU de Bordeaux , Bordeaux , France.,c INSERM U1211, Maladies Rares, Génétique et Métabolisme , Université de Bordeaux , Bordeaux , France
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Parsons BL. Multiclonal tumor origin: Evidence and implications. MUTATION RESEARCH-REVIEWS IN MUTATION RESEARCH 2018; 777:1-18. [PMID: 30115427 DOI: 10.1016/j.mrrev.2018.05.001] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Revised: 04/11/2018] [Accepted: 05/05/2018] [Indexed: 12/31/2022]
Abstract
An accurate understanding of the clonal origins of tumors is critical for designing effective strategies to treat or prevent cancer and for guiding the field of cancer risk assessment. The intent of this review is to summarize evidence of multiclonal tumor origin and, thereby, contest the commonly held assumption of monoclonal tumor origin. This review describes relevant studies of X chromosome inactivation, analyses of tumor heterogeneity using other markers, single cell sequencing, and lineage tracing studies in aggregation chimeras and engineered rodent models. Methods for investigating tumor clonality have an inherent bias against detecting multiclonality. Despite this, multiclonality has been observed within all tumor stages and within 53 different types of tumors. For myeloid tumors, monoclonal tumor origin may be the predominant path to cancer and a monoclonal tumor origin cannot be ruled out for a fraction of other cancer types. Nevertheless, a large body of evidence supports the conclusion that most cancers are multiclonal in origin. Cooperation between different cell types and between clones of cells carrying different genetic and/or epigenetic lesions is discussed, along with how polyclonal tumor origin can be integrated with current perspectives on the genesis of tumors. In order to develop biologically sound and useful approaches to cancer risk assessment and precision medicine, mathematical models of carcinogenesis are needed, which incorporate multiclonal tumor origin and the contributions of spontaneous mutations in conjunction with the selective advantages conferred by particular mutations and combinations of mutations. Adherence to the idea that a growth must develop from a single progenitor cell to be considered neoplastic has outlived its usefulness. Moving forward, explicit examination of tumor clonality, using advanced tools, like lineage tracing models, will provide a strong foundation for future advances in clinical oncology and better training for the next generation of oncologists and pathologists.
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Affiliation(s)
- Barbara L Parsons
- US Food and Drug Administration, National Center for Toxicological Research, Division of Genetic and Molecular Toxicology, 3900 NCTR Rd., Jefferson, AR 72079, United States.
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Variable X-chromosome inactivation and enlargement of pericentral glutamine synthetase zones in the liver of heterozygous females with OTC deficiency. Virchows Arch 2018; 472:1029-1039. [PMID: 29623395 DOI: 10.1007/s00428-018-2345-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2017] [Revised: 02/27/2018] [Accepted: 03/23/2018] [Indexed: 01/28/2023]
Abstract
Ornithine transcarbamylase (OTC) deficiency is an X-linked disorder that causes recurrent and life-threatening episodes of hyperammonemia. The clinical picture in heterozygous females is highly diverse and derives from the genotype and the degree of inactivation of the mutated X chromosome in hepatocytes. Here, we describe molecular genetic, biochemical, and histopathological findings in the livers explanted from two female patients with late-onset OTC deficiency. Analysis of X-inactivation ratios by DNA methylation-based assays showed remarkable intra-organ variation ranging from 46:54 to 82:18 (average 70:30, n = 37), in favor of the active X chromosome carrying the mutation c.583G>C (p.G195R), in the first patient and from 75:25 to 90:10 (average 82:18, n = 20) in favor of the active X chromosome carrying the splicing mutation c.663+1G>A in the second patient. The X-inactivation ratios in liver samples correlated highly with the proportions of OTC-positive hepatocytes calculated from high-resolution image analyses of the immunohistochemically detected OTC in frozen sections that was performed on total area > 5 cm2. X-inactivation ratios in blood in both female patients corresponded to the lower limit of the liver values. Our data indicate that the proportion of about 20-30% of hepatocytes expressing the functional OTC protein is not sufficient to maintain metabolic stability. X-inactivation ratios assessed in liver biopsies taken from heterozygous females with X-linked disorders should not be considered representative of the whole liver.
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8
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Vacca M, Della Ragione F, Scalabrì F, D'Esposito M. X inactivation and reactivation in X-linked diseases. Semin Cell Dev Biol 2016; 56:78-87. [PMID: 26994527 DOI: 10.1016/j.semcdb.2016.03.009] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2016] [Revised: 03/10/2016] [Accepted: 03/11/2016] [Indexed: 12/22/2022]
Abstract
X chromosome inactivation (XCI) is the phenomenon by which mammals compensate for dosage of X-linked genes in females (XX) versus males (XY). XCI patterns can be random or show extreme skewing, and can modify the mode of inheritance of X-driven phenotypes, which contributes to the variability of human pathologies. Recent findings have shown reversibility of the XCI process, which has opened new avenues in the approaches used for the treatment of X-linked diseases.
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Affiliation(s)
- Marcella Vacca
- Institute of Genetics and Biophysics "A. Buzzati Traverso", CNR, via Pietro Castellino, 111, 80131, Naples, Italy.
| | - Floriana Della Ragione
- Institute of Genetics and Biophysics "A. Buzzati Traverso", CNR, via Pietro Castellino, 111, 80131, Naples, Italy; IRCCS Neuromed, Pozzilli, Isernia, Italy
| | | | - Maurizio D'Esposito
- Institute of Genetics and Biophysics "A. Buzzati Traverso", CNR, via Pietro Castellino, 111, 80131, Naples, Italy; IRCCS Neuromed, Pozzilli, Isernia, Italy
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9
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MECP2 mutations in Czech patients with Rett syndrome and Rett-like phenotypes: novel mutations, genotype–phenotype correlations and validation of high-resolution melting analysis for mutation scanning. J Hum Genet 2016; 61:617-25. [DOI: 10.1038/jhg.2016.19] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2015] [Revised: 01/06/2016] [Accepted: 02/15/2016] [Indexed: 02/04/2023]
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