title: Is the 1p/19q deletion a diagnostic marker of oligodendrogliomas?
abstract: The diagnosis and classification of diffusely infiltrative gliomas are based on their histopathological appearance; however, histopathological delineation of diffuse gliomas can be difficult because of vague and subjective histopathological criteria. Combined loss of chromosome arms 1p and 19q (denoted as 1p-/19q-) has proven to be a powerful predictor of chemotherapeutic response and survival in oligodendrogliomas. We undertook retrospective and prospective studies of brain tumor patients originally diagnosed as oligodendrogliomas or oligoastrocytomas patients followed at our institution using molecular genetic techniques. Fluorescence in situ hybridization using probes specific for chromosomes 1 and 19 was performed on 22 paraffin-embedded tissues retrospectively; 15 touch-preparation smear samples were studied prospectively; and loss of heterozygosity (LOH) screening was performed on 11 samples with microsatellite markers specific to chromosome 1 and chromosome 19. Of the 37 cases, 24 had 1p-/19q-, 1 case had 1p- only, 2 cases had 19q- only, and 10 cases had no deletion. The length of the largest deletion was mapped between markers D1S2795 (1p36.31 locus) and D1S2722 (1p34.2 locus) and between markers D19S416 (19q13.11 locus) and D19S397 (19q13.14 locus), using LOH. All of the pure oligodendrogliomas (n=7) harbored 1p-/19q-. In light of previous findings, the 1p-/19q- combination appears to be an objective diagnosis marker of classic oligodendrogliomas, one that can be used, in combination with histological examination, to improve the diagnosis of oligodendroglioma. Fluorescence in situ hybridization on touch preparations is a simple way to obtain information on 1p-/19q- in 24 hours.
authors.affiliation: Division of Genetics, Department of Pediatrics, Faculty of Medicine and Health Sciences, University of Sherbrooke, 3001 12th Avenue North, Quebec, Canada.
authors.forename: Macoura
authors.initials: M
authors.lastname: Gadji
authors.forename: David
authors.initials: D
authors.lastname: Fortin
authors.forename: Ana-Maria
authors.initials: AM
authors.lastname: Tsanaclis
authors.forename: Régen
authors.initials: R
authors.lastname: Drouin
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002872:Chromosome Deletion; D002878:Chromosomes, Human, Pair 1 / Q000235:genetics*; D002888:Chromosomes, Human, Pair 19 / Q000235:genetics*; D005260:Female; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D053208:Kaplan-Meier Estimate; D019656:Loss of Heterozygosity; D008297:Male; D018895:Microsatellite Repeats / Q000235:genetics; D008875:Middle Aged; D009837:Oligodendroglioma / Q000175:diagnosis* / Q000235:genetics*; D016133:Polymerase Chain Reaction; D012680:Sensitivity and Specificity; D055815:Young Adult