The LGG IDH mutant subtype is further classified based on the codeletion of 1p/19q where LGG IDH mutant patients harboring 1p/19q codeletion is termed as oligodendrogliomas (ODG) while LGG IDH mutant patients having intact 1p/19q loci are termed as diffuse astrocytoma which may be enriched in TP53 mutation/ATRX loss. The gene discussed is ATRX; the disease is oligodendroglioma.