Anatomy and Neuroscience - Research Publications

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    IDH1 mutation is associated with seizures and protoplasmic subtype in patients with low-grade gliomas
    Liubinas, SV ; D'Abaco, GM ; Moffat, BM ; Gonzales, M ; Feleppa, F ; Nowell, CJ ; Gorelik, A ; Drummond, KJ ; O'Brien, TJ ; Kaye, AH ; Morokoff, AP (WILEY, 2014-09)
    OBJECTIVE: The isocitrate dehydrogenase 1 (IDH1) R132H mutation is the most common mutation in World Health Organization (WHO) grade II gliomas, reported to be expressed in 70-80%, but only 5-10% of high grade gliomas. Low grade tumors, especially the protoplasmic subtype, have the highest incidence of tumor associated epilepsy (TAE). The IDH1 mutation leads to the accumulation of 2-hydroxyglutarate (2HG), a metabolite that bears a close structural similarity to glutamate, an excitatory neurotransmitter that has been implicated in the pathogenesis of TAE. We hypothesized that expression of mutated IDH1 may play a role in the pathogenesis of TAE in low grade gliomas. METHODS: Thirty consecutive patients with WHO grade II gliomas were analyzed for the presence of the IDH1-R132H mutation using immunohistochemistry. The expression of IDH1 mutation was semiquantified using open-source biologic-imaging analysis software. RESULTS: The percentage of cells positive for the IDH1-R132H mutation was found to be higher in patients with TAE compared to those without TAE (median and interquartile range (IQR) 25.3% [8.6-53.5] vs. 5.2% [0.6-13.4], p = 0.03). In addition, we found a significantly higher median IDH1 mutation expression level in the protoplasmic subtype of low grade glioma (52.2% [IQR 19.9-58.6] vs. 13.8% [IQR 3.9-29.4], p = 0.04). SIGNIFICANCE: Increased expression of the IDH1-R132H mutation is associated with seizures in low grade gliomas and also with the protoplasmic subtype. This supports the hypothesis that this mutation may play a role in the pathogenesis of both TAE and low grade gliomas.