Isocitrate dehydrogenase 1(IDH1) gene mutations occur in ~ 60 - 90%of diffuse and anaplastic gliomas and secondaryglioblastomas. IDH status is strongly associatedwith patient survival times and IDHtesting is relevant for clinical patient managementand for stratification in clinical trials.A recent interlaboratory ring trial showsthat immunohistochemistry is a highly reliablemethod to detect the most common IDHmutation (R132H), while IDH gene sequencingis less robust. These results support initialimmunohistochemistry and subsequentgene sequencing in cases with negative orinconclusive immunostaining result as validalgorithm for IDH testing. Furthermore, theyhighlight the need for strict quality control ofDNA-based biomarker analyses on formalinfixedand paraffin-embedded tumor samples.

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Clinical Neuropathology
Erasmus MC: University Medical Center Rotterdam

Preusser, M, & van den Bent, M.J. (2013). Clinical neuropathology practice news 2-2013: Immunohistochemistry pins IDH in glioma - molecular testing procedures under scrutiny. Clinical Neuropathology, 32(2), 82–83. doi:10.5414/NP300622