Postzygotic mosaicism in SMC1A and the first reported case of a female with Cornelia de Lange syndrome

Abstract Postzygotic mosaicism (PZM) has been increasingly recognized in Cornelia de Lange syndrome (CdLS). However, it has been scarcely described when the genetic cause resides in SMC1A, an X-linked cohesin member implicated in approximately 5% of cases. Here, we report the first female patient wi...

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Main Authors: Marta Gil-Salvador, Laura Trujillano, Cristina Lucia-Campos, Julia Del Rincón, Pilar Pamplona, María Arnedo, Beatriz Puisac, Íñigo Marcos-Alcalde, Paulino Gómez-Puertas, Feliciano J. Ramos, Juan Pié, Ana Latorre-Pellicer
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Language:English
Published: Nature Portfolio 2025-07-01
Series:Scientific Reports
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Online Access:https://doi.org/10.1038/s41598-025-07268-z
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author Marta Gil-Salvador
Laura Trujillano
Cristina Lucia-Campos
Julia Del Rincón
Pilar Pamplona
María Arnedo
Beatriz Puisac
Íñigo Marcos-Alcalde
Paulino Gómez-Puertas
Feliciano J. Ramos
Juan Pié
Ana Latorre-Pellicer
author_facet Marta Gil-Salvador
Laura Trujillano
Cristina Lucia-Campos
Julia Del Rincón
Pilar Pamplona
María Arnedo
Beatriz Puisac
Íñigo Marcos-Alcalde
Paulino Gómez-Puertas
Feliciano J. Ramos
Juan Pié
Ana Latorre-Pellicer
author_sort Marta Gil-Salvador
collection DOAJ
description Abstract Postzygotic mosaicism (PZM) has been increasingly recognized in Cornelia de Lange syndrome (CdLS). However, it has been scarcely described when the genetic cause resides in SMC1A, an X-linked cohesin member implicated in approximately 5% of cases. Here, we report the first female patient with classic CdLS harboring a PZM variant in SMC1A and provide a comprehensive characterization of mosaicism in this gene. The identified PZM variant [SMC1A:NM_006306.3:c.2369 = /G > A; p.(Arg790Gln)], was detected in blood and buccal swab-derived DNA at around 30% allele frequency. Molecular dynamics simulations suggest that this mutation disrupts the elbow domain of SMC1A, potentially impairing cohesin function. Further delineation of phenotypes and genotypes associated with PZM variants in SMC1A reveals that, similar to constitutive variants, mosaic mutations are predominantly missense and distributed throughout the gene. Moreover, the phenotype of patients carrying mosaic variants is clinically indistinguishable from those with constitutive mutations, and purifying selection of the pathogenic variant in blood is suggested, as previously observed in NIPBL-related CdLS. However, this process may be more complex in SMC1A due to its X-linked nature. Our findings underscore the importance of high-sensitivity sequencing techniques for detecting mosaicism and highlight the complexity of X-linked mosaic variants in disease expressivity. Further functional studies and larger cohorts are crucial to improve genotype–phenotype correlations and diagnostics in CdLS.
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spelling doaj-art-a7988618dfed48eabe7e890385be37742025-08-20T04:01:23ZengNature PortfolioScientific Reports2045-23222025-07-0115111110.1038/s41598-025-07268-zPostzygotic mosaicism in SMC1A and the first reported case of a female with Cornelia de Lange syndromeMarta Gil-Salvador0Laura Trujillano1Cristina Lucia-Campos2Julia Del Rincón3Pilar Pamplona4María Arnedo5Beatriz Puisac6Íñigo Marcos-Alcalde7Paulino Gómez-Puertas8Feliciano J. Ramos9Juan Pié10Ana Latorre-Pellicer11Unit of Clinical Genetics and Functional Genomics, Department of Pharmacology and Physiology, School of Medicine, University of Zaragoza, CIBERER and IIS-AragonUnit of Clinical Genetics and Functional Genomics, Department of Pharmacology and Physiology, School of Medicine, University of Zaragoza, CIBERER and IIS-AragonUnit of Clinical Genetics and Functional Genomics, Department of Pharmacology and Physiology, School of Medicine, University of Zaragoza, CIBERER and IIS-AragonUnit of Clinical Genetics and Functional Genomics, Department of Pharmacology and Physiology, School of Medicine, University of Zaragoza, CIBERER and IIS-AragonUnit of Clinical Genetics and Functional Genomics, Department of Pharmacology and Physiology, School of Medicine, University of Zaragoza, CIBERER and IIS-AragonUnit of Clinical Genetics and Functional Genomics, Department of Pharmacology and Physiology, School of Medicine, University of Zaragoza, CIBERER and IIS-AragonUnit of Clinical Genetics and Functional Genomics, Department of Pharmacology and Physiology, School of Medicine, University of Zaragoza, CIBERER and IIS-AragonMolecular Modeling Group, Centro de Biología Molecular Severo Ochoa (CBM, CSIC-UAM)Molecular Modeling Group, Centro de Biología Molecular Severo Ochoa (CBM, CSIC-UAM)Unit of Clinical Genetics, Service of Paediatrics, Department of Paediatrics, School of Medicine, University Hospital Lozano Blesa, University of Zaragoza, CIBERER and IIS-AragonUnit of Clinical Genetics and Functional Genomics, Department of Pharmacology and Physiology, School of Medicine, University of Zaragoza, CIBERER and IIS-AragonUnit of Clinical Genetics and Functional Genomics, Department of Pharmacology and Physiology, School of Medicine, University of Zaragoza, CIBERER and IIS-AragonAbstract Postzygotic mosaicism (PZM) has been increasingly recognized in Cornelia de Lange syndrome (CdLS). However, it has been scarcely described when the genetic cause resides in SMC1A, an X-linked cohesin member implicated in approximately 5% of cases. Here, we report the first female patient with classic CdLS harboring a PZM variant in SMC1A and provide a comprehensive characterization of mosaicism in this gene. The identified PZM variant [SMC1A:NM_006306.3:c.2369 = /G > A; p.(Arg790Gln)], was detected in blood and buccal swab-derived DNA at around 30% allele frequency. Molecular dynamics simulations suggest that this mutation disrupts the elbow domain of SMC1A, potentially impairing cohesin function. Further delineation of phenotypes and genotypes associated with PZM variants in SMC1A reveals that, similar to constitutive variants, mosaic mutations are predominantly missense and distributed throughout the gene. Moreover, the phenotype of patients carrying mosaic variants is clinically indistinguishable from those with constitutive mutations, and purifying selection of the pathogenic variant in blood is suggested, as previously observed in NIPBL-related CdLS. However, this process may be more complex in SMC1A due to its X-linked nature. Our findings underscore the importance of high-sensitivity sequencing techniques for detecting mosaicism and highlight the complexity of X-linked mosaic variants in disease expressivity. Further functional studies and larger cohorts are crucial to improve genotype–phenotype correlations and diagnostics in CdLS.https://doi.org/10.1038/s41598-025-07268-zCornelia de Lange syndromeSMC1APostzygotic mosaicismDeep-sequencingX-linked inheritance
spellingShingle Marta Gil-Salvador
Laura Trujillano
Cristina Lucia-Campos
Julia Del Rincón
Pilar Pamplona
María Arnedo
Beatriz Puisac
Íñigo Marcos-Alcalde
Paulino Gómez-Puertas
Feliciano J. Ramos
Juan Pié
Ana Latorre-Pellicer
Postzygotic mosaicism in SMC1A and the first reported case of a female with Cornelia de Lange syndrome
Scientific Reports
Cornelia de Lange syndrome
SMC1A
Postzygotic mosaicism
Deep-sequencing
X-linked inheritance
title Postzygotic mosaicism in SMC1A and the first reported case of a female with Cornelia de Lange syndrome
title_full Postzygotic mosaicism in SMC1A and the first reported case of a female with Cornelia de Lange syndrome
title_fullStr Postzygotic mosaicism in SMC1A and the first reported case of a female with Cornelia de Lange syndrome
title_full_unstemmed Postzygotic mosaicism in SMC1A and the first reported case of a female with Cornelia de Lange syndrome
title_short Postzygotic mosaicism in SMC1A and the first reported case of a female with Cornelia de Lange syndrome
title_sort postzygotic mosaicism in smc1a and the first reported case of a female with cornelia de lange syndrome
topic Cornelia de Lange syndrome
SMC1A
Postzygotic mosaicism
Deep-sequencing
X-linked inheritance
url https://doi.org/10.1038/s41598-025-07268-z
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