Article
IDH 1/2 mutations in astrocytomas WHO grade II: association with localization and seizure as initial symptom
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Published: | June 4, 2012 |
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Objective: Seizures are the most common initial symptom in patients with low-grade gliomas and strongly depend on the site of the tumour. The majority of low-grade gliomas reveal mutations in the genes encoding isocitrate-dehydrogenase 1 (IDH1) or 2 (IDH2). These mutations are associated with metabolic changes that might have epileptogenic potential. We investigated the correlation of IDH1/2 mutations with localization of the tumour and seizures as initial symptoms.
Methods: Patients with astrocytoma WHO grade II, cortical infiltration, filed initial symptom and available tissue for IDH1/2 analysis were included in this retrospective study. IDH1/2 mutation analysis was performed by direct sequencing or by immunohistochemistry with an antibody detecting mutated protein IDH1 R132H. In case of negative immunohistochemistry, sequencing was performed. IDH1/2 status was defined as mutated, if any of these investigations were positive.
Results: Seventy-nine patients were included. IDH1 or IDH2 mutation was present in 63 (80%) patients, which were in the mean younger than patients without IDH1/2 mutation (40 vs. 47 years, p = 0.0331, t-test). IDH1/2 mutations were associated to frontal tumour location (p = 0.0202). All 12 tumours in the insula revealed IDH1/2 mutations. Seizure as initial symptom was recorded in 57 (72%) patients and was associated with IDH1 or IDH2 mutation by multivariate analysis (OR 22.563, p = 0.0019).
Conclusions: In astrocytomas WHO grade II IDH1/2 mutations mostly occur in tumours infiltrating the frontal lobe. Seizure as initial symptom is associated with IDH1 or IDH2 mutation.