In the 2016 WHO update, the classification of adult-type diffuse gliomas was based on IDH mutation, and astrocytomas and oligodendrogliomas were subclassified by determining the TP53, ATRX, 1p/19q codeletion status, while diffuse midline gliomas were defined with the H3K27M mutation [33]. The gene discussed is ATRX; the disease is astrocytoma (excluding glioblastoma).