The identification of mutations by NGS would result nowadays in a change in diagnosis in two cases (6.25% of the patients): the first one, an astrocytoma, IDH mutated, grade 4, in a 34-year-old patient with IDH mutation at p.R132G (not previously identified by immunohistochemistry that targets R132H); and the second one, an H3G34 mutated Diffuse Hemispheric Glioma in a 28-year-old patient, with ATRX (alpha-thalassemia/mental retardation, X-linked) and H3G34 mutations. Here, IDH1 is linked to Alpha-thalassemia.