ATRX and glioblastoma: Secondly, somatic mutations of the histone variant H3.3, alpha-thalassemia X-linked syndrome protein (ATRX) and death associated protein (DAXX) have been found in ALT cancers, including pancreatic neuroendocrine (panNET) cancers and glioblastoma multiforme (GBM) cancers30, 31.