Rapid detection of mutation in isocitrate dehydrogenase 1 and 2 genes using mass spectrometry

The 2016 World Health Organization classification of tumors of the central nervous system was recently revised. Mutations in the isocitrate dehydrogenase 1 (IDH1) and IDH2 genes and chromosome 1p/19q codeletion are especially important for both the integrated diagnosis and the determination of surgical strategy. To establish a method for intraoperative molecular diagnosis, a simple, rapid method was developed for the measurement of 2-hydroxyglutarate (2-HG), a specific oncometabolite formed in the presence of IDH gene mutation, using liquid chromatography/electrospray ionization tandem mass spectrometry (LC/ESI–MS/MS). This method requires only 10 min to measure the level of 2-HG from tissue preparation to completion of examination. Using this method, the level of 2-HG was analyzed in 105 patients with diffuse infiltrating glioma, and showed that IDH mutated glioma had significantly higher level of 2-HG compared to IDH wild-type glioma. Receiver operating characteristic curve analysis showed the area under the curve, sensitivity, and specificity were 0.9815, 97.5, and 100%, respectively. In contrast, tumor grade and presence of chromosome 1p/19q codeletion in the IDH mutated glioma could not be predicted from the level of 2-HG. Measurement of 2-HG level using LC/ESI–MS/MS can provide rapid and accurate information of mutation status in the IDH gene.