IDH2 mutations are commonly associated with 1p/19q codeletion in diffuse adult gliomas
Authors: Romain Appay, Emeline Tabouret, Nicolas Macagno, Mehdi Touat, Catherine Carpentier, Carole Colin, François Ducray, Ahmed Idbaih, Karima Mokhtari, Emmanuelle Uro-Coste, Caroline Dehais, Dominique Figarella-Branger, C Desenclos, H Sevestre, P Menei, A Rousseau, T Cruel, S Lopez, M-I Mihai, A Petit, C Adam, F Parker, P Dam-Hieu, I Quintin-Roué, S Eimer, H Loiseau, L Bekaert, F Chapon, D Ricard, C Godfraind, T Khallil, D Cazals-Hatem, T Faillot, C Gaultier, M C Tortel, I Carpiuc, P Richard, W Lahiani, H Aubriot-Lorton, F Ghiringhelli, C A Maurage, C Ramirez, E M Gueye, F Labrousse, O Chinot, L Bauchet, V Rigau, P Beauchesne, G Gauchotte, M Campone, D Loussouarn, D Fontaine, F Vandenbos-Burel, A Le Floch, P Roger, C Blechet, M Fesneau, A Carpentier, J Y Delattre, S Elouadhani-Hamdi, M Polivka, D Larrieu-Ciron, S Milin, P Colin, M D Diebold, D Chiforeanu, E Vauleon, O Langlois, A Laquerriere, F Forest, M J Motso-Fotso, M Andraud, G Runavot, B Lhermitte, G Noel, S Gaillard, C Villa, N Desse, C Rousselot-Denis, I Zemmoura, E Cohen-Moyal, E Uro-Coste, F Dhermain
Journal: Neuro-Oncology (2018)

IDH2 mutations are commonly associated with 1p/19q codeletion in diffuse adult gliomasDiffuse gliomas are classified according to the 2016 World Health Organization (WHO) Classification of Tumors of the Central Nervous System, 1 which combines histological and molecular features.Diagnosis requires the assessment of mutations in the isocitrate dehydrogenase genes (IDH1 and IDH2), key genetic alterations characterizing gliomas with favorable outcome. 2 Because IDH1 and IDH2 are highly similar enzymes, the WHO classification, as most of the current studies, combines these mutations into the same molecular group; however, it is unclear whether these tumors share the same characteristics.We analyzed data from 1517 patients included in the French POLA Network to investigate differences between IDH1-and IDH2-mutant gliomas.Inclusion criteria were the written consent of the patient for clinical data collection and genetic analysis and sufficient material for molecular studies allowing classification according to the 2016 WHO classification.IDH1-R132H mutational status was evaluated using automated immunohistochemistry in all cases (n = 1517).Direct sequencing 3 was performed in 978 cases and demonstrated IDH mutation in 573 cases (this includes confirmation of IDH1-R132H mutation in 468 cases, other IDH1 mutations in 61 cases, and IDH2 mutation in 44 cases).The 1p/19q codeletion status was determined based on single nucleotide polymorphism arrays, comparative genomic hybridization arrays, and/ or microsatellite marker analysis. 3The following data were recorded: age, sex, follow-up, and MRI features (tumor location, extension, contrast enhancement, edema).All statistical analysis was done using IBM SPSS statistics software version 23.Chi-square test was used to compare qualitative variables.Continuous variables were compared using the Mann-Whitney U-test, and the Kaplan-Meier method was used to estimate survival distributions.Among the 1517 patients, 1025 had an IDH-mutant tumor: 96% were IDH1-mutant and 4% IDH2-mutant.Integrated diagnoses are summarized in Fig. 1.The frequency of 1p/19q codeletion was higher in the IDH2-mutant group compared with the IDH1-mutant group (91% vs 48%, P < 0.001).Wang and coworkers previously reported higher frequency of 1p/19q codeletion in IDH2-mutant gliomas (9/18 samples) compared with IDH1-mutant. 4The percentage of each category