Recently, it has been shown that many ALT-positive tumors, including PanNETs, oligodendrogliomas, and GBM, contain inactivating mutations in ATRX and/or DAXX, implicating the possible role of ATRX/DAXX inactivation in the manifestation of the ALT phenotype (23, 26). This evidence concerns the gene GPT and glioblastoma.