Methodology: IHC

Clinical Significance:
Identifies: Isocitrate dehydrogenase 1, an enzyme that participates in the citric acid cycle, and is mutated in a high fraction of gliomas and oligodendrogliomas, particularly in grade II and grade III neoplasms. In these tumors, the overwhelming majority show a point mutation on codon 132 (R132H). The availability of a monoclonal antibody specific for the mutated IDH1, which does not cross react with the native protein, has provided an immunohistochemical tool that can be used to positively identify these tumors. Furthermore, because IDH mutations do not occur in reactive gliosis, the latter can often be separated from diffuse gliomas, which are usually positive for the mutation (and hence positive by IHC). Subcellular Localization: Nuclear and cytoplasmic

Organ: Brain/CNS

Disease State: Oligodendroglioma

CPT Code(s): 88342 or 88341 (reference only; CPTs may vary)

Turnaround Time: Within 1-2 business days of receipt

Schedule: Monday - Friday

Specimen Requirements:
• Formalin-fixed, paraffin-embedded (FFPE) tissue block or cell block - OR - • 1 unstained slide for each test requested plus 3-4 additional unstained slides cut at 4µm