The genetic hallmark of IDH-mutant astrocytoma, in general, is the presence of IDH1/2, TP53 and ATRX mutations, whereas IDH-wild-type glioblastomas show TERT promoter mutations, CDKN2A/B homozygous loss, TP53 and PTEN mutations, as most frequent common alterations [3]. The gene discussed is CDKN2A; the disease is glioblastoma.