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Huselid E, Bunting SF. The Regulation of Homologous Recombination by Helicases. Genes (Basel) 2020; 11:genes11050498. [PMID: 32369918 PMCID: PMC7290689 DOI: 10.3390/genes11050498] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2020] [Revised: 04/29/2020] [Accepted: 04/29/2020] [Indexed: 11/16/2022] Open
Abstract
Homologous recombination is essential for DNA repair, replication and the exchange of genetic material between parental chromosomes during meiosis. The stages of recombination involve complex reorganization of DNA structures, and the successful completion of these steps is dependent on the activities of multiple helicase enzymes. Helicases of many different families coordinate the processing of broken DNA ends, and the subsequent formation and disassembly of the recombination intermediates that are necessary for template-based DNA repair. Loss of recombination-associated helicase activities can therefore lead to genomic instability, cell death and increased risk of tumor formation. The efficiency of recombination is also influenced by the ‘anti-recombinase’ effect of certain helicases, which can direct DNA breaks toward repair by other pathways. Other helicases regulate the crossover versus non-crossover outcomes of repair. The use of recombination is increased when replication forks and the transcription machinery collide, or encounter lesions in the DNA template. Successful completion of recombination in these situations is also regulated by helicases, allowing normal cell growth, and the maintenance of genomic integrity.
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Giorgio E, Brussino A, Biamino E, Belligni EF, Bruselles A, Ciolfi A, Caputo V, Pizzi S, Calcia A, Di Gregorio E, Cavalieri S, Mancini C, Pozzi E, Ferrero M, Riberi E, Borelli I, Amoroso A, Ferrero GB, Tartaglia M, Brusco A. Exome sequencing in children of women with skewed X-inactivation identifies atypical cases and complex phenotypes. Eur J Paediatr Neurol 2017; 21:475-484. [PMID: 28027854 DOI: 10.1016/j.ejpn.2016.12.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/29/2016] [Revised: 11/03/2016] [Accepted: 12/11/2016] [Indexed: 12/30/2022]
Abstract
BACKGROUND More than 100 X-linked intellectual disability (X-LID) genes have been identified to be involved in 10-15% of intellectual disability (ID). METHOD To identify novel possible candidates, we selected 18 families with a male proband affected by isolated or syndromic ID. Pedigree and/or clinical presentation suggested an X-LID disorder. After exclusion of known genetic diseases, we identified seven cases whose mother showed a skewed X-inactivation (>80%) that underwent whole exome sequencing (WES, 50X average depth). RESULTS WES allowed to solve the genetic basis in four cases, two of which (Coffin-Lowry syndrome, RPS6K3 gene; ATRX syndrome, ATRX gene) had been missed by previous clinical/genetics tests. One further ATRX case showed a complex phenotype including pontocerebellar atrophy (PCA), possibly associated to an unidentified PCA gene mutation. In a case with suspected Lujan-Fryns syndrome, a c.649C>T (p.Pro217Ser) MECP2 missense change was identified, likely explaining the neurological impairment, but not the marfanoid features, which were possibly associated to the p.Thr1020Ala variant in fibrillin 1. Finally, a c.707T>G variant (p.Phe236Cys) in the DMD gene was identified in a patient retrospectively recognized to be affected by Becker muscular dystrophy (BMD, OMIM 300376). CONCLUSION Overall, our data show that WES may give hints to solve complex ID phenotypes with a likely X-linked transmission, and that a significant proportion of these orphan conditions might result from concomitant mutations affecting different clinically associated genes.
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Affiliation(s)
- Elisa Giorgio
- University of Torino, Department of Medical Sciences, 10126, Turin, Italy
| | | | - Elisa Biamino
- University of Torino, Department of Public Health and Pediatrics, 10126, Turin, Italy
| | - Elga Fabia Belligni
- University of Torino, Department of Public Health and Pediatrics, 10126, Turin, Italy
| | - Alessandro Bruselles
- Genetics and Rare Diseases Research Division, Ospedale Pediatrico Bambino Gesù IRCSS, Rome, Italy
| | - Andrea Ciolfi
- Genetics and Rare Diseases Research Division, Ospedale Pediatrico Bambino Gesù IRCSS, Rome, Italy
| | - Viviana Caputo
- Department of Experimental Medicine, Sapienza University of Rome, Rome, Italy
| | - Simone Pizzi
- Genetics and Rare Diseases Research Division, Ospedale Pediatrico Bambino Gesù IRCSS, Rome, Italy
| | - Alessandro Calcia
- University of Torino, Department of Medical Sciences, 10126, Turin, Italy
| | - Eleonora Di Gregorio
- University of Torino, Department of Medical Sciences, 10126, Turin, Italy; Città della Salute e della Scienza University Hospital, Medical Genetics Unit, Turin, Italy
| | - Simona Cavalieri
- University of Torino, Department of Medical Sciences, 10126, Turin, Italy
| | - Cecilia Mancini
- University of Torino, Department of Medical Sciences, 10126, Turin, Italy
| | - Elisa Pozzi
- University of Torino, Department of Medical Sciences, 10126, Turin, Italy
| | - Marta Ferrero
- University of Torino, Department of Medical Sciences, 10126, Turin, Italy
| | - Evelise Riberi
- University of Torino, Department of Public Health and Pediatrics, 10126, Turin, Italy
| | - Iolanda Borelli
- University of Torino, Department of Medical Sciences, 10126, Turin, Italy
| | - Antonio Amoroso
- University of Torino, Department of Medical Sciences, 10126, Turin, Italy
| | | | - Marco Tartaglia
- Genetics and Rare Diseases Research Division, Ospedale Pediatrico Bambino Gesù IRCSS, Rome, Italy
| | - Alfredo Brusco
- University of Torino, Department of Medical Sciences, 10126, Turin, Italy; Città della Salute e della Scienza University Hospital, Medical Genetics Unit, Turin, Italy.
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Syndromic disorder of sex development due to a novel hemizygous mutation in the carboxyl-terminal domain of ATRX. Hum Genome Var 2017; 4:17012. [PMID: 28446958 PMCID: PMC5389957 DOI: 10.1038/hgv.2017.12] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2016] [Revised: 02/04/2017] [Accepted: 03/01/2017] [Indexed: 12/31/2022] Open
Abstract
Alpha-thalassemia/mental retardation syndrome X-linked (ATRX; OMIM #301040), which is caused by mutations in the ATRX gene, is characterized by alpha-thalassemia, distinct dysmorphic facies, psychomotor development delay and genital abnormalities. Here, we describe a neonatal case of syndromic disorder of sex development, harboring a novel hemizygous mutation, p.Asp2352fs*1 in the carboxyl-terminal domain of ATRX. Our study provides additional evidence that deletion of the carboxyl terminus of ATRX is associated with severe genital anomalies.
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