ATRX and astrocytoma (excluding glioblastoma): IDHmut appears to be the first alteration to occur in IDHmut astrocytomas, with TP53 and/or ATRX arising later.7,8 In the current case, the initial tumor was diagnosed by microscopy as a grade 2 astrocytoma, about 10 years before the discovery of IDHmut in gliomas.