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El Hawary R, Meshaal S, Lotfy S, Abd Elaziz D, Alkady R, Eldash A, Erfan A, Chohayeb E, Saad M, Darwish R, Boutros J, Galal N, Elmarsafy A. Cernunnos deficiency: Further delineation in 5 Egyptian patients. Eur J Med Genet 2023; 66:104840. [PMID: 37703920 DOI: 10.1016/j.ejmg.2023.104840] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2023] [Revised: 08/13/2023] [Accepted: 09/10/2023] [Indexed: 09/15/2023]
Abstract
Cernunnos deficiency is a rare genetic disorder characterized by immunodeficiency, microcephaly, growth retardation, bird-like facies, sensitivity to ionizing radiation, few autoimmune manifestations, premature aging of hematopoietic stem cells at an early age, and occasional myeloproliferative disease. Herein we present five Egyptian Cernunnos patients from 3 different families. We describe the patients' clinical phenotypes, their immunological profile as well as genetic results. Sequence analysis revealed three different mutations in the NHEJ1 gene: a nonsense variant c.532C > T; p.(Arg178Ter), an intronic variant c.178-1G > A and a frameshift insertion variant c.233dup; p.(Asn78LysfsTer14). In conclusion, Cernunnos deficiency can have a wide range of clinical features. The characteristic immune profile including a decrease in recent thymic emigrants and naive T cells, markedly elevated memory T cells together with normal to high IgM, and a decrease in IgG and IgA. This immune profile is highly suggestive of Cernunnos deficiency in T-B-NK + SCID patients especially surviving for older ages.
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Affiliation(s)
- Rabab El Hawary
- Clinical and Chemical Pathology Department, Faculty of Medicine, Cairo University, Cairo, Egypt.
| | - Safa Meshaal
- Clinical and Chemical Pathology Department, Faculty of Medicine, Cairo University, Cairo, Egypt
| | - Sohilla Lotfy
- Department of Pediatrics, Faculty of Medicine, Cairo University, Cairo, Egypt
| | - Dalia Abd Elaziz
- Department of Pediatrics, Faculty of Medicine, Cairo University, Cairo, Egypt
| | - Radwa Alkady
- Department of Pediatrics, Faculty of Medicine, Cairo University, Cairo, Egypt
| | - Alia Eldash
- Clinical and Chemical Pathology Department, Faculty of Medicine, Cairo University, Cairo, Egypt
| | - Aya Erfan
- Clinical and Chemical Pathology Department, Faculty of Medicine, Cairo University, Cairo, Egypt
| | - Engy Chohayeb
- Department of Pediatrics, Faculty of Medicine, Cairo University, Cairo, Egypt
| | - Mai Saad
- Department of Pediatrics, Faculty of Medicine, Cairo University, Cairo, Egypt
| | - Rania Darwish
- Clinical and Chemical Pathology Department, Faculty of Medicine, Cairo University, Cairo, Egypt
| | - Jeannette Boutros
- Department of Pediatrics, Faculty of Medicine, Cairo University, Cairo, Egypt
| | - Nermeen Galal
- Department of Pediatrics, Faculty of Medicine, Cairo University, Cairo, Egypt
| | - Aisha Elmarsafy
- Department of Pediatrics, Faculty of Medicine, Cairo University, Cairo, Egypt
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Castañeda-Zegarra S, Xing M, Gago-Fuentes R, Sæterstad S, Oksenych V. Synthetic lethality between DNA repair factors Xlf and Paxx is rescued by inactivation of Trp53. DNA Repair (Amst) 2018; 73:164-169. [PMID: 30579708 DOI: 10.1016/j.dnarep.2018.12.002] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2018] [Revised: 12/04/2018] [Accepted: 12/14/2018] [Indexed: 02/03/2023]
Abstract
Non-homologous end joining (NHEJ) is a DNA repair pathway that senses, processes and ligates DNA double-strand breaks (DSBs) throughout the cell cycle. During NHEJ, core Ku70 and Ku80 subunits bind DSBs as a heterodimer and promote further recruitment of accessory factors (e.g., PAXX, Mri, DNA-PKcs, Artemis) and downstream core subunits XRCC4 and DNA ligase 4 (Lig4). Inactivation of Ku70 or Ku80 genes in mice results in immunodeficiency and high levels of genomic instability; deletion of individual Dna-pkcs, Xlf, Paxx or Mri genes results in viable mice with no or modest DNA repair defects. However, combined inactivation of either Xlf and Dna-pkcs, or Xlf and Paxx, or Xlf and Mri, leads to synthetic lethality in mice, which correlates with increased levels of apoptosis in the central nervous system. Here, we demonstrated that inactivation of pro-apoptotic factor Trp53 rescues embryonic lethality of Xlf-/-Paxx-/- and Xlf-/-Dna-pkcs-/- double knockout mice. Moreover, combined inactivation of Paxx and Dna-pkcs results in live-born fertile Paxx-/-Dna-pkcs-/- mice indistinguishable from Dna-pkcs-/- knockout controls.
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Affiliation(s)
- Sergio Castañeda-Zegarra
- Department of Clinical and Molecular Medicine, Norwegian University of Science and Technology, Laboratory Center, Erling Skjalgssons gate 1, 7491, Trondheim, Norway; St. Olavs Hospital, Trondheim University Hospital, Clinic of Medicine, Postboks 3250 Sluppen, 7006, Trondheim, Norway; Department of Biomedicine, University of Bergen, Bergen, Norway
| | - Mengtan Xing
- Department of Clinical and Molecular Medicine, Norwegian University of Science and Technology, Laboratory Center, Erling Skjalgssons gate 1, 7491, Trondheim, Norway; St. Olavs Hospital, Trondheim University Hospital, Clinic of Medicine, Postboks 3250 Sluppen, 7006, Trondheim, Norway
| | - Raquel Gago-Fuentes
- Department of Clinical and Molecular Medicine, Norwegian University of Science and Technology, Laboratory Center, Erling Skjalgssons gate 1, 7491, Trondheim, Norway; St. Olavs Hospital, Trondheim University Hospital, Clinic of Medicine, Postboks 3250 Sluppen, 7006, Trondheim, Norway
| | - Siri Sæterstad
- Department of Clinical and Molecular Medicine, Norwegian University of Science and Technology, Laboratory Center, Erling Skjalgssons gate 1, 7491, Trondheim, Norway; St. Olavs Hospital, Trondheim University Hospital, Clinic of Medicine, Postboks 3250 Sluppen, 7006, Trondheim, Norway
| | - Valentyn Oksenych
- Department of Clinical and Molecular Medicine, Norwegian University of Science and Technology, Laboratory Center, Erling Skjalgssons gate 1, 7491, Trondheim, Norway; St. Olavs Hospital, Trondheim University Hospital, Clinic of Medicine, Postboks 3250 Sluppen, 7006, Trondheim, Norway; Department of Biosciences and Nutrition, Karolinska Institutet, Huddinge, Sweden.
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Gago‐Fuentes R, Xing M, Sæterstad S, Sarno A, Dewan A, Beck C, Bradamante S, Bjørås M, Oksenych V. Normal development of mice lacking PAXX, the paralogue of XRCC4 and XLF. FEBS Open Bio 2018; 8:426-434. [PMID: 29511619 PMCID: PMC5832975 DOI: 10.1002/2211-5463.12381] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2017] [Revised: 12/18/2017] [Accepted: 01/04/2018] [Indexed: 02/05/2023] Open
Abstract
DNA repair consists of several cellular pathways which recognize and repair damaged DNA. The classical nonhomologous DNA end-joining (NHEJ) pathway repairs double-strand breaks in DNA. It is required for maturation of both B and T lymphocytes by supporting V(D)J recombination as well as B-cell differentiation during class switch recombination (CSR). Inactivation of NHEJ factors Ku70, Ku80, XRCC4, DNA ligase 4, DNA-PKcs, and Artemis impairs V(D)J recombination and blocks lymphocyte development. Paralogue of XRCC4 and XLF (PAXX) is an accessory NHEJ factor that has a significant impact on the repair of DNA lesions induced by ionizing radiation in human, murine, and chicken cells. However, the role of PAXX during development is poorly understood. To determine the physiological role of PAXX, we deleted part of the Paxx promoter and the first two exons in mice. Further, we compared Paxx-knockout mice with wild-type (WT) and NHEJ-deficient controls including Ku80- and Dna-pkcs-null and severe combined immunodeficiency mice. Surprisingly, Paxx-deficient mice were not distinguishable from the WT littermates; they were the same weight and size, fertility status, had normal spleen, thymus, and bone marrow. Paxx-deficient mice had the same number of chromosomal and chromatid breaks as WT mice. Moreover, Paxx-deficient primary B lymphocytes had the same level of CSR as lymphocytes isolated from WT mice. We concluded that PAXX is dispensable for normal mouse development.
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Affiliation(s)
- Raquel Gago‐Fuentes
- Institute of Clinical and Molecular Medicine (IKOM)Laboratory CenterNorwegian University of Science and TechnologyTrondheimNorway
| | - Mengtan Xing
- Institute of Clinical and Molecular Medicine (IKOM)Laboratory CenterNorwegian University of Science and TechnologyTrondheimNorway
| | - Siri Sæterstad
- Institute of Clinical and Molecular Medicine (IKOM)Laboratory CenterNorwegian University of Science and TechnologyTrondheimNorway
| | - Antonio Sarno
- Institute of Clinical and Molecular Medicine (IKOM)Laboratory CenterNorwegian University of Science and TechnologyTrondheimNorway
- St. Olavs HospitalClinic of MedicineTrondheim University HospitalTrondheimNorway
| | - Alisa Dewan
- Institute of Clinical and Molecular Medicine (IKOM)Laboratory CenterNorwegian University of Science and TechnologyTrondheimNorway
- Present address:
Centre for Immune Regulation and Department of ImmunologyOslo University Hospital‐RikshospitaletUniversity of OsloOsloNorway
- Present address:
KG Jebsen Coeliac Disease Research CentreUniversity of OsloOsloNorway
| | - Carole Beck
- Institute of Clinical and Molecular Medicine (IKOM)Laboratory CenterNorwegian University of Science and TechnologyTrondheimNorway
| | - Stefano Bradamante
- Institute of Clinical and Molecular Medicine (IKOM)Laboratory CenterNorwegian University of Science and TechnologyTrondheimNorway
| | - Magnar Bjørås
- Institute of Clinical and Molecular Medicine (IKOM)Laboratory CenterNorwegian University of Science and TechnologyTrondheimNorway
- Department of MicrobiologyOslo University HospitalUniversity of OsloOsloNorway
| | - Valentyn Oksenych
- Institute of Clinical and Molecular Medicine (IKOM)Laboratory CenterNorwegian University of Science and TechnologyTrondheimNorway
- St. Olavs HospitalClinic of MedicineTrondheim University HospitalTrondheimNorway
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Kumar V, Alt FW, Oksenych V. Reprint of "Functional overlaps between XLF and the ATM-dependent DNA double strand break response". DNA Repair (Amst) 2014; 17:52-63. [PMID: 24767946 DOI: 10.1016/j.dnarep.2014.04.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2013] [Revised: 01/14/2014] [Accepted: 01/24/2014] [Indexed: 02/08/2023]
Abstract
Developing B and T lymphocytes generate programmed DNA double strand breaks (DSBs) during the V(D)J recombination process that assembles exons that encode the antigen-binding variable regions of antibodies. In addition, mature B lymphocytes generate programmed DSBs during the immunoglobulin heavy chain (IgH) class switch recombination (CSR) process that allows expression of different antibody heavy chain constant regions that provide different effector functions. During both V(D)J recombination and CSR, DSB intermediates are sensed by the ATM-dependent DSB response (DSBR) pathway, which also contributes to their joining via classical non-homologous end-joining (C-NHEJ). The precise nature of the interplay between the DSBR and C-NHEJ pathways in the context of DSB repair via C-NHEJ remains under investigation. Recent studies have shown that the XLF C-NHEJ factor has functional redundancy with several members of the ATM-dependent DSBR pathway in C-NHEJ, highlighting unappreciated major roles for both XLF as well as the DSBR in V(D)J recombination, CSR and C-NHEJ in general. In this review, we discuss current knowledge of the mechanisms that contribute to the repair of DSBs generated during B lymphocyte development and activation with a focus on potential functionally redundant roles of XLF and ATM-dependent DSBR factors.
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Affiliation(s)
- Vipul Kumar
- Howard Hughes Medical Institute, Program in Cellular and Molecular Medicine, Boston Children's Hospital, Department of Genetics, Harvard Medical School, Boston, MA 02115, United States
| | - Frederick W Alt
- Howard Hughes Medical Institute, Program in Cellular and Molecular Medicine, Boston Children's Hospital, Department of Genetics, Harvard Medical School, Boston, MA 02115, United States.
| | - Valentyn Oksenych
- Howard Hughes Medical Institute, Program in Cellular and Molecular Medicine, Boston Children's Hospital, Department of Genetics, Harvard Medical School, Boston, MA 02115, United States.
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Kumar V, Alt FW, Oksenych V. Functional overlaps between XLF and the ATM-dependent DNA double strand break response. DNA Repair (Amst) 2014; 16:11-22. [PMID: 24674624 DOI: 10.1016/j.dnarep.2014.01.010] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2013] [Revised: 01/14/2014] [Accepted: 01/24/2014] [Indexed: 11/27/2022]
Abstract
Developing B and T lymphocytes generate programmed DNA double strand breaks (DSBs) during the V(D)J recombination process that assembles exons that encode the antigen-binding variable regions of antibodies. In addition, mature B lymphocytes generate programmed DSBs during the immunoglobulin heavy chain (IgH) class switch recombination (CSR) process that allows expression of different antibody heavy chain constant regions that provide different effector functions. During both V(D)J recombination and CSR, DSB intermediates are sensed by the ATM-dependent DSB response (DSBR) pathway, which also contributes to their joining via classical non-homologous end-joining (C-NHEJ). The precise nature of the interplay between the DSBR and C-NHEJ pathways in the context of DSB repair via C-NHEJ remains under investigation. Recent studies have shown that the XLF C-NHEJ factor has functional redundancy with several members of the ATM-dependent DSBR pathway in C-NHEJ, highlighting unappreciated major roles for both XLF as well as the DSBR in V(D)J recombination, CSR and C-NHEJ in general. In this review, we discuss current knowledge of the mechanisms that contribute to the repair of DSBs generated during B lymphocyte development and activation with a focus on potential functionally redundant roles of XLF and ATM-dependent DSBR factors.
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Affiliation(s)
- Vipul Kumar
- Howard Hughes Medical Institute, Program in Cellular and Molecular Medicine, Boston Children's Hospital, Department of Genetics, Harvard Medical School, Boston, MA 02115, United States
| | - Frederick W Alt
- Howard Hughes Medical Institute, Program in Cellular and Molecular Medicine, Boston Children's Hospital, Department of Genetics, Harvard Medical School, Boston, MA 02115, United States.
| | - Valentyn Oksenych
- Howard Hughes Medical Institute, Program in Cellular and Molecular Medicine, Boston Children's Hospital, Department of Genetics, Harvard Medical School, Boston, MA 02115, United States.
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