IDH1 and glioma: Frontal and INGs, with the highest IDH-mutant rates among gliomas, are both in close proximity to the subventricular zone (SVZ) of neural progenitor cells.55, 56The SVZ is, in turn, adjacent to the area around the rostral extension of the lateral ventricle, reported as the cellular origin of IDH-mutant glioblastomas.55This may justify the high distribution of IDH-mutant gliomas to the insula, frontal lobe, or both, and the higher occurrence of frontoinsular growth pattern in IDH-mutant than in IDH-wild-type paralimbic gliomas.