IDH1 and neoplasm: Additionally, ATRX mutations were identified in three H3/IDH1 wildtype tumor pairs, two of which co-occurred with alterations in chromatin modifiers (HGG8, HGG9), and in both samples from patients with germline NF1. We observed the same ATRX mutation at recurrence in all tumor pairs of the H3/IDH1 wildtype subgroup.