title: BRAF-KIAA1549 fusion transcripts are less frequent in pilocytic astrocytomas diagnosed in adults.
abstract: OBJECTIVE
  Duplication of 7q34 resulting in generation of BRAF-KIAA1549 fusion transcripts is a characteristic event in pilocytic astrocytoma that may also aid distinction from diffuse astrocytic tumours. As data on BRAF-KIAA1549 fusion transcript status remain mainly limited to children, we aimed to examine the diagnostic value of BRAF-KIAA1549 fusion transcripts across all age groups.
  
  
  METHODS
  BRAF-KIAA1549 fusion transcript status was examined using reverse transcription polymerase chain reaction on formalin-fixed paraffin-embedded samples of 105 primary pilocytic astrocytomas [median patient age: 17 years (1-74 years)].
  
  
  RESULTS
  Informative results (distinct wildtype BRAF bands detectable) were obtained in 105/124 cases (85%). Fusion transcripts were detected in 53 of cases (51%). They were more often encountered in tumours of infratentorial location [42/67 (63%) vs. 11/38 (29%)] and comprised KIAA1549-Ex16_BRAF-Ex9 (32 cases), KIAA1549-Ex15_BRAF-Ex9 (14 cases) and KIAA1549-Ex16_BRAF-Ex11 (seven cases). Fusion transcripts were present in 79% of tumours diagnosed in the first decade of life, but only in 51% of patients aged 11-20 years, 42% of patients aged 21-30 years, 30% of patients aged 31-40 years and 7% of patients older than 40 years. On multivariate logistic regression analysis, the association of fusion transcript status and age was confirmed adjusting for tumour location (P = 0.006).
  
  
  CONCLUSIONS
  The frequency of BRAF-KIAA1549 fusion transcripts is significantly lower in adult patients with pilocytic astrocytoma, weakening the sensitivity of this specific diagnostic marker in that age group.
authors.affiliation: Institute of Neuropathology, University Hospital Münster, Münster, Germany. hasselblatt@uni-muenster.de
authors.forename: M
authors.initials: M
authors.lastname: Hasselblatt
authors.forename: B
authors.initials: B
authors.lastname: Riesmeier
authors.forename: B
authors.initials: B
authors.lastname: Lechtape
authors.forename: A
authors.initials: A
authors.lastname: Brentrup
authors.forename: W
authors.initials: W
authors.lastname: Stummer
authors.forename: F K
authors.initials: FK
authors.lastname: Albert
authors.forename: A
authors.initials: A
authors.lastname: Sepehrnia
authors.forename: H
authors.initials: H
authors.lastname: Ebel
authors.forename: J
authors.initials: J
authors.lastname: Gerss
authors.forename: W
authors.initials: W
authors.lastname: Paulus
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D001254:Astrocytoma / Q000175:diagnosis / Q000235:genetics*; D001932:Brain Neoplasms / Q000175:diagnosis / Q000235:genetics*; D002648:Child; D002675:Child, Preschool; D006801:Humans; D007223:Infant; D008875:Middle Aged; D015514:Oncogene Proteins, Fusion / Q000235:genetics*
chemical_list: C568616:BRAF-KIAA1549 fusion protein, human; D015514:Oncogene Proteins, Fusion