Article Text

PDF
Short report
Microduplications upstream of MSX2 are associated with a phenocopy of cleidocranial dysplasia
  1. Claus Eric Ott1,
  2. Hendrikje Hein2,3,
  3. Silke Lohan1,2,
  4. Jeannette Hoogeboom4,
  5. Nicola Foulds5,
  6. Johannes Grünhagen1,
  7. Sigmar Stricker1,2,
  8. Pablo Villavicencio-Lorini1,2,
  9. Eva Klopocki1,2,
  10. Stefan Mundlos1,2,3
  1. 1Institute for Medical Genetics and Human Genetics, Charité-Universitätsmedizin Berlin, Berlin, Germany
  2. 2Research Group Development and Disease, Max-Planck Institute for Molecular Genetics, Berlin, Germany
  3. 3Berlin-Brandenburg Center for Regenerative Therapies (BCRT), Berlin, Germany
  4. 4Department of Clinical Genetics, Erasmus MC, University Medical Center, Rotterdam, The Netherlands
  5. 5Department of Human Genetics and Genomic Medicine, University Hospital of Southampton NHS Foundation Trust, Faculty of Medicine, University of Southampton, Hampshire, UK
  1. Correspondence to Dr rer. nat. Eva Klopocki, Institute for Medical Genetics and Human Genetics, Charité-Universitätsmedizin Berlin, Augustenburger Platz 1, 13353 Berlin, Germany; eva.klopocki{at}charite.de

Abstract

Background Cleidocranial dysplasia (CCD) is an autosomal dominant skeletal disorder characterised by hypoplastic or absent clavicles, increased head circumference, large fontanels, dental anomalies and short stature. Although CCD is usually caused by mutations leading to haploinsufficiency of RUNX2, the underlying genetic cause remains unresolved in about 25% of cases.

Methods Array comparative genomic hybridisation was performed to detect copy number variations (CNVs). Identified CNVs were characterised by quantitative PCR and sequencing analyses. The effect of candidate genes on mineralisation was evaluated using viral overexpression in chicken cells.

Results In 2 out of 16 cases, the authors identified microduplications upstream of MSX2 on chromosome 5q35.2. One of the unrelated affected individuals presented with a phenocopy of CCD. In addition to a classical CCD phenotype, the other subject had a complex synpolydactyly of the hands and postaxial polydactyly of the feet which have so far never been reported in association with CCD or CNVs on 5q35.2. The duplications overlap in an ∼219 kb region that contains several highly conserved non-coding elements which are likely to be involved in MSX2 gene regulation. Functional analyses demonstrated that the inhibitory effect of Msx2 overexpression on mineralisation cannot be ameliorated by forced Runx2 expression.

Conclusions These results indicate that CNVs in non-coding regions can cause developmental defects, and that the resulting phenotype can be distinct from those caused by point mutations within the corresponding gene. Taken together, these findings reveal an additional mechanism for the pathogenesis of CCD, particularly with regard to the regulation of MSX2.

  • Copy number
  • genetics
  • connective tissue disease
  • clinical genetics
  • developmental
  • chromosomal
  • microarray
  • genetic screening/counselling
  • molecular genetics

Statistics from Altmetric.com

Footnotes

  • Funding This work was supported by the Deutsche Forschungsgemeinschaft (DFG) grant number SFB 760, MU 880/11-01 and KL 2158/2-1.

  • Competing interests None.

  • Patient consent Obtained.

  • Ethics approval Ethics approval was provided by the Charité-Universitätsmedizin Berlin ethical board.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Data sharing statement Primer sequences are available in supplementary data and on request. Detailed protocol information is available upon request.

Request permissions

If you wish to reuse any or all of this article please use the link below which will take you to the Copyright Clearance Center’s RightsLink service. You will be able to get a quick price and instant permission to reuse the content in many different ways.