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An intronic splice site alteration in combination with a large deletion affecting VPS13B (COH1) causes Cohen syndrome.
Metadata
Journaleuropean journal of medical genetics2.368Date
2020 Jun 04
4 months ago
Type
Journal Article
Volume
2020-Sep / 63 : 103973
Author
Boschann F 1, Fischer-Zirnsak B 2, Wienker TF 3, Holtgrewe M 4, Seelow D 5, Eichhorn B 6, Döhnert S 6, Fahsold R 6, Horn D 7, Graul-Neumann LM 8
Affiliation
  • 2. Charité - Universitätsmedizin Berlin, Institut für Medizinische Genetik und Humangenetik, Augustenburger Platz 1, 13353, Berlin, Germany; Max-Planck-Institut für Molekulare Genetik, RG Development & Disease, Ihnestr. 63-73, 14195, Berlin, Germany.
  • 3. Max-Planck-Institut für Molekulare Genetik, Dept. Human Molecular Genetics, Ihnestr. 63-73, 14195, Berlin, Germany.
  • 4. Berliner Institut für Gesundheitsforschung, Core Unit Bioinformatics, Charitéplatz 1, 10117, Berlin, Germany; Charité - Universitätsmedizin Berlin, Charité - Zentrum für Therapieforschung, Charitéplatz 1, 10117, Berlin, Germany.
  • 5. Charité - Universitätsmedizin Berlin, Institut für Medizinische Genetik und Humangenetik, Augustenburger Platz 1, 13353, Berlin, Germany; Berliner Institut für Gesundheitsforschung (BIH), RG Bioinformatics and Translational Genetics, Charitéplatz 1, 10117, Berlin, Germany.
  • 6. MVZ Mitteldeutscher Praxisverbund Humangenetik GmbH, Friedrichstrasse 38-40, 01067, Dresden, Germany.
  • 7. Charité - Universitätsmedizin Berlin, Institut für Medizinische Genetik und Humangenetik, Augustenburger Platz 1, 13353, Berlin, Germany.
  • 8. Charité - Universitätsmedizin Berlin, Institut für Medizinische Genetik und Humangenetik, Augustenburger Platz 1, 13353, Berlin, Germany. Electronic address: [email protected]
Doi
PMIDMESH
Abstract
Cohen syndrome (CS) is a rare, autosomal recessive disorder characterized by intellectual disability, postnatal microcephaly, facial abnormalities, abnormal truncal fat distribution, myopia, and pigmentary retinopathy. It is often considered an underdiagnosed condition, especially in children with developmental delay and intellectual disability. Here we report on four individuals from a large Jordanian family clinically diagnosed with CS. Using Trio Exome Sequencing (Trio-WES) and MLPA analyses we identified a maternally inherited novel intronic nucleotide substitution c.3446-23T>G leading to the activation of a cryptic splice site and a paternally inherited multi-exon deletion in VPS13B (previously termed COH1) in the index patient. Expression analysis showed a strong decrease of VPS13B mRNA levels and direct sequencing of cDNA confirmed splicing at a cryptic upstream splice acceptor site, resulting in the inclusion of 22 intronic bases. This extension results in a frameshift and a premature stop of translation (p.Gly1149Valfs*9). Segregation analysis revealed that three affected maternal cousins were homozygous for the intronic splice site variant. Our data show causality of both alterations and strongly suggest the expansion of the diagnostic strategy to search for intronic splice variants in molecularly unconfirmed patients affected by CS.
Keywords: COH1 Cohen syndrome Compound heterozygous mutation Copy number variation Splice site mutation VPS13B WES
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Eur J Med Geneteuropean journal of medical genetics
Metadata
LocationNetherlands
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