Genomic duplication of PTPN11 is an uncommon cause of Noonan syndrome

John M. Graham, Nancy Kramer, Bassem A. Bejjani, Christian T. Thiel, Claudio Carta, Giovanni Neri, Marco Tartaglia, Martin Zenker

Research output: Contribution to journalArticle

Abstract

Noonan syndrome (NS) is a genetically heterogeneous disorder caused most commonly by activating mutations in PTPN11. We report a patient with hypotonia, developmental delay and clinical features suggestive of NS. High-resolution chromosome analysis was normal, and sequence analyses of PTPN11, SOS1, KRAS, BRAF, RAF1, MEK, and MEK2 were also normal. Array CGH revealed a single copy gain of 9 BAC clones at 12q24.11q24.21 (8.98Mb in size), which encompassed the PTPN11 locus at 12q24.13 and was confirmed by FISH analysis. Shchelochkov et al. [Shchelochkov et al. (2008); Am J Med Genet Part A 146A:1042-1048] reported a similar case and speculated that such duplications might account for 15-30% of NS cases with no detectable mutation in NS genes. We screened more than 250 NS cases without mutation in known NS disease-causing genes by quantitative PCR, and none of these studies produced results in the duplicated range. We also explored the possibility that de novo changes affecting the untranslated region (UTR) of the PTPN11 transcript might represent an alternative event involved in SHP2 enhanced expression. DHPLC analysis and direct sequencing of the entire 3′ UTR in 36 NS patients without mutation in known genes did not show any disease-associated variant. These findings indicate that duplications of PTPN11 represent an uncommon cause of NS, and functionally relevant variations within the 3′ UTR of the gene do not appear to play a major role in NS. However, recurrent observations of NS in individuals with duplications involving the PTPN11 locus suggest that increased dosage of SHP2 may have dysregulating effects on intracellular signaling.

Original languageEnglish
Pages (from-to)2122-2128
Number of pages7
JournalAmerican Journal of Medical Genetics, Part A
Volume149
Issue number10
DOIs
Publication statusPublished - Oct 2009

Keywords

  • Array CGH
  • Dosage sensitive gene
  • Duplication 12q24.3
  • Gene duplication PTPN11
  • Noonan syndrome
  • PTPN11
  • TBX3
  • TBX5

ASJC Scopus subject areas

  • Genetics(clinical)
  • Genetics

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  • Cite this

    Graham, J. M., Kramer, N., Bejjani, B. A., Thiel, C. T., Carta, C., Neri, G., Tartaglia, M., & Zenker, M. (2009). Genomic duplication of PTPN11 is an uncommon cause of Noonan syndrome. American Journal of Medical Genetics, Part A, 149(10), 2122-2128. https://doi.org/10.1002/ajmg.a.32992