title: [Loss of heterozygosity on chromosomes 1 and 19 in cases of primary brain tumour].
abstract: BACKGROUND
  Histological classification of brain tumours, including gliomas, can be difficult, and genetic investigations are increasingly significant in their classification and the development of treatment strategies. Oligodendrogliomas often show a loss of heterozygocity for the short arm of chromosome 1 and the long arm of chromosome 19 (LOH 1p/19q), changes that influence both treatment and prognosis. Our aim was to evaluate the incidence of combined loss of heterozygocity 1p and 19q in various glioma groups.
  
  
  METHODS
  A total of 10 oligodendrogliomas (5 WHO grade II and 5 grade III), 10 mixed gliomas (5 WHO grade II and 5 grade III), 10 astrocytomas (5 WHO grade II and 5 grade III) and 11 glioblastomas (WHO grade IV) were investigated. Normal hippocampal tissue was used as a control. Formalin-fixed paraffin-embedded tissue was scrutinized with fluorescent in situ hybridization (FISH) with fluorochrome-conjugated double-strand DNA probes for 1p and 19q, respectively.
  
  
  RESULTS
  A significiant loss of 1p/19q was found in the oligodendrogliomas; the astrocytomas showed a selective loss of 19q; the glioblastomas showed a selective loss of 1p but also polyploidy.
  
  
  CONCLUSIONS
  This investigation confirms other reports on increased LOH 1p/19q in oligodendrogliomas. Various studies have demonstrated a large variation in the incidence of LOH 1p/19q. This might be due to inter- and intraobserver variability in the histological classification. Another factor might be variations in techniques. Most studies have been made on imprints. A standard for the method, including the number of cells counted, the cutoff limit and the statistical variation, is necessary for future studies and clinical use.
authors.affiliation: Neuropatologisk Laboratorium, H:S Rigshospitalet, DK-2100 København Ø.
authors.forename: Pernille Wolder
authors.initials: PW
authors.lastname: Born
authors.forename: Helle
authors.initials: H
authors.lastname: Broholm
authors.forename: Henning
authors.initials: H
authors.lastname: Laursen
mesh_terms: D001254:Astrocytoma / Q000235:genetics / Q000473:pathology / Q000628:therapy; D001932:Brain Neoplasms / Q000235:genetics* / Q000473:pathology / Q000628:therapy; D002878:Chromosomes, Human, Pair 1 / Q000235:genetics*; D002888:Chromosomes, Human, Pair 19 / Q000235:genetics*; D005909:Glioblastoma / Q000235:genetics / Q000473:pathology / Q000628:therapy; D005910:Glioma / Q000235:genetics* / Q000473:pathology / Q000628:therapy; D006801:Humans; D017403:In Situ Hybridization; D019656:Loss of Heterozygosity; D009367:Neoplasm Staging; D009837:Oligodendroglioma / Q000235:genetics / Q000473:pathology / Q000628:therapy