KIAA1549-BRAF fusions and IDH mutations can coexist in diffuse gliomas of adults

Brain Pathol. 2012 Nov;22(6):841-7. doi: 10.1111/j.1750-3639.2012.00603.x. Epub 2012 Jun 18.

Abstract

KIAA1549-BRAF fusion gene and isocitrate dehydrogenase (IDH) mutations are considered two mutually exclusive genetic events in pilocytic astrocytomas and diffuse gliomas, respectively. We investigated the presence of the KIAA1549-BRAF fusion gene in conjunction with IDH mutations and 1p/19q loss in 185 adult diffuse gliomas. Moreover BRAF(v600E) mutation was also screened. The KIAA1549-BRAF fusion gene was evaluated by reverse-transcription polymerase chain reaction (RT-PCR) and sequencing. We found IDH mutations in 125 out 175 cases (71.4%). There were KIAA1549-BRAF fusion gene in 17 out of 180 (9.4%) cases and BRAF(v600E) in 2 out of 133 (1.5%) cases. In 11 of these 17 cases, both IDH mutations and the KIAA1549-BRAF fusion were present, as independent molecular events. Moreover, 6 of 17 cases showed co-presence of 1p/19q loss, IDH mutations and KIAA1549-BRAF fusion. Among the 17 cases with KIAA1549-BRAF fusion gene 15 (88.2%) were oligodendroglial neoplasms. Similarly, the two cases with BRAF(v600E) mutation were both oligodendroglioma and one had IDH mutations and 1p/19q co-deletion. Our results suggest that in a small fraction of diffuse gliomas, KIAA1549-BRAF fusion gene and BRAF(v600E) mutation may be responsible for deregulation of the Ras-RAF-ERK signaling pathway. Such alterations are more frequent in oligodendroglial neoplasm and may be co-present with IDH mutations and 1p/19q loss.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Brain Neoplasms / genetics*
  • Female
  • Glioma / genetics*
  • Humans
  • Isocitrate Dehydrogenase / genetics*
  • Male
  • Middle Aged
  • Oncogene Proteins, Fusion / genetics*
  • Reverse Transcriptase Polymerase Chain Reaction
  • Young Adult

Substances

  • BRAF-KIAA1549 fusion protein, human
  • Oncogene Proteins, Fusion
  • Isocitrate Dehydrogenase