IDH1; IDH2; CADMA; Glioma; Mutation testing

Mutations in IDH1/2 genes are a marker of good prognosis for glioma patients, associated with low grade gliomas and secondaryglioblastomas. Immunohistochemistry and Sanger sequencing are current standards for IDH1/2 genotyping while many othermethods exist. The aim of this study was to validate Competitive amplification of differentially melting amplicons (CADMA)PCR for IDH genotyping by comparison with SNaPshot assay and two immunohistochemical methods. In our study, 87 gliomapatients (46 from Olomouc and 41 from Ostrava) were analyzed. IDH1/2 mutations in native bioptical samples were analyzed atDNA level by CADMA and SNaPshot while IDH1 mutations in FFPE samples were analyzed at protein level by two IHCmethods. CADMA PCR sensitivity for IDH1 was 96.4% and specificity 100% for 86 concluded samples. SNaPshot assaysensitivity was 92.9% and specificity of 100% for 85 concluded samples. IHC in the laboratory no. 2 reached sensitivity85.7% and specificity 100% for 86 concluded samples. IHC in the laboratory no. 4 reached sensitivity of 96.4% and specificityof 79.7% in 74 concluded samples. Only one IDH2 mutation was found by SNaPshot while CADMA yielded false negativeresult. In conclusion, CADMA is a valid method for IDH1 p.(R132H) testing with higher sensitivity than SNaPshot assay. Also,molecular genetic methods of IDH1 testing from native samples were more robust than IHC from FFPE.