TERT and astrocytoma (excluding glioblastoma): In addition, frequent TERT (telomerase reverse transcriptase) promoter mutations and a lack of nuclear trimethylation at lysine 27 of histone 3 (H3K27me3) can be observed, whereas astrocytomas have frequent mutations in the α-thalassaemia/mental retardation syndrome X-linked (ATRX) and TP53 genes (Yan et al. 2009; Reifenberger et al. 1994; Louis et al. 2016).