title: Value and limitations of immunohistochemistry and gene sequencing for detection of the IDH1-R132H mutation in diffuse glioma biopsy specimens.
abstract: To assess the value of anti-isocitrate dehydrogenase 1 (IDH1) immunohistochemistry for evaluating diffuse gliomas, we analyzed anti-IDH1-R132H immunohistochemistry using monoclonal antibodies DIA-H09 and IMab-1 and IDH1 gene sequencing in formalin-fixed and paraffin-embedded biopsy samples of 95 diffuse gliomas. We found concordant immunostaining results using the 2 antibodies in 94 (98.9%) of the 95 cases, but DIA-H09 generally showed a higher signal-to-background ratio than IMab-1 did. Fifty-five percent of cases showed anti-IDH1-R132H immunostaining of virtually all tumor cells and 15% of only a fraction of tumor cells. All cases with complete or partial immunostaining of the tumor tissue carried the IDH1-R132H mutation. In all cases with negative immunostaining results (approximately 30%), genetic analysis showed IDH1 wild-type or non-R132H-IDH1 mutations. In a single tiny biopsy, both anti-IDH1-R132H antibodies showed immunoreactivity, but genetic testing was inconclusive. Our data confirm anti-IDH1-R132H immunostaining as a reliable method for evaluation of IDH1 gene mutation status. They also suggest the following: (i) in some cases, nonspecific background staining or regional heterogeneity of IDH1-R132H protein expression may necessitate confirmatory genetic analysis; (ii) for individual cases, anti-IDH1-R132H immunostaining may not reliably identify infiltrating tumor cells admixed with preexisting or reactive glial cells; and (iii) in tiny biopsies, immunohistochemistry may be more sensitive for detection of IDH1-R132H mutation than genetic analysis.
authors.affiliation: Department of Medicine I, Medical University of Vienna, Vienna, Austria.
authors.forename: Matthias
authors.initials: M
authors.lastname: Preusser
authors.forename: Adelheid
authors.initials: A
authors.lastname: Wöhrer
authors.forename: Susanne
authors.initials: S
authors.lastname: Stary
authors.forename: Romana
authors.initials: R
authors.lastname: Höftberger
authors.forename: Berthold
authors.initials: B
authors.lastname: Streubel
authors.forename: Johannes A
authors.initials: JA
authors.lastname: Hainfellner
mesh_terms: D001120:Arginine / Q000235:genetics*; D001706:Biopsy; D001932:Brain Neoplasms / Q000175:diagnosis* / Q000235:genetics*; D005820:Genetic Testing; D005910:Glioma / Q000175:diagnosis / Q000235:genetics*; D006639:Histidine / Q000235:genetics*; D006801:Humans; D007150:Immunohistochemistry / Q000379:methods; D007521:Isocitrate Dehydrogenase / Q000235:genetics*; D009154:Mutation / Q000235:genetics*; D015203:Reproducibility of Results; D017421:Sequence Analysis / Q000379:methods
chemical_list: D006639:Histidine; D001120:Arginine; D007521:Isocitrate Dehydrogenase; C543588:IDH1 protein, human