F.1 DNA methylome profiling identifies stability of IDH mutations throughout glioma evolution

Background: Isocitrate dehydrogenase (IDH) mutation status is a key diagnostic and prognostic feature of gliomas. There are conflicting reports regarding the stability IDH mutations throughout glioma evolution treatment. Here, we provide an institutional experience patients with longitudinally in order to determine if changes over time. Methods: We retrospectively identified from 2009-2018 immunohistochemistry (IHC)-recorded discrepancies longitudinally. Archived frozen tissue samples were analyzed using methylation profiling, Sanger sequencing, droplet digital PCR (ddPCR). Results compared IHC-reported status. Results: reviewed 1491 archived including 91 multiple tumour collected In all instances discrepancy, found reasonable explanations through multi-platform profiling that resolved discrepancies. This included presence non-canonical IDH2 sequencing perilesional or reactive brain profiling. Conclusions: Our findings support hypothesis occur early gliomagenesis stable treatment evolution. study highlights importance accurate surgical sampling role DNA methylome diagnostically uncertain cases for integrated pathological molecular diagnosis.