Holt-Oram syndrome with intermediate atrioventricular canal defect, and aortic coarctation: Functional characterization of a de novo TBX5 mutation

Anwar Baban, Letizia Pitto, Silvia Pulignani, Monica Cresci, Laura Mariani, Carolina Gambacciani, Maria Cristina Digilio, Giacomo Pongiglione, Sonia Albanese

Research output: Contribution to journalArticle

Abstract

Holt-Oram syndrome (HOS) is a rare autosomal dominant disorder characterized by upper limb defects and congenital heart defects (CHD), which are often simple septal and conduction defects, less frequently complex CHDs. We report on a 9 year-old boy with clinical and radiologic features of HOS consisting of bilateral asymmetric hypoplastic thumbs, generalized brachydactyly, limited supination due to radioulnar synostosis, and sloping shoulders, and intermediate atrioventricular canal defect (AVCD) with aortic coarctation. A de novo, previously described mutation, (Arg279ter) was identified in the TBX5 gene. Molecular characterization of this mutation was carried out due to the atypical CHD. In order to investigate whether the mutated transcript of TBX5 was able to escape the post-transcriptional surveillance mechanism and to produce a truncated TBX5 protein, we analyzed the TBX5 transcript, and protein pattern in HOS, and WT cardiac tissues. Our results demonstrate that the mutant TBX5 transcript is cleared by the cellular mechanism of surveillance. This data provides some support for the hypothesis that a dominant negative mutation, which strongly impairs the WT allele, might be too hazardous to be maintained. The literature suggests that HOS is relatively common among syndromes associated with AVCD.

Original languageEnglish
Pages (from-to)1419-1424
Number of pages6
JournalAmerican Journal of Medical Genetics, Part A
Volume164
Issue number6
DOIs
Publication statusPublished - 2014

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Keywords

  • Aortic coarctation (COA)
  • Atrioventricular canal defect (AVCD)
  • Holt-Oram syndrome (HOS)
  • TBX5

ASJC Scopus subject areas

  • Genetics(clinical)
  • Genetics
  • Medicine(all)

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