ATRX and glioma: Similar to recent studies demonstrating alternative lengthening of telomeres (ALT) driven by ATRX inactivation in NF1-associated malignancies [4, 25], 53% of the gliomas in our high-grade molecular group (9/17) had inactivating ATRX mutations, with uniform absence of TERT promoter mutation or other TERT alterations.