Almost all GBM and GSC couples had polysomy of chromosome 7, monosomy of chromosome 10 (PTEN), and deletions at chromosome 9p21 (CDKN2A) that are typical features of primary GBM, essential for gliomagenesis and usually conserved in the whole GBM mass [13, 26, 28, 29, 37]. The gene discussed is CDKN2A; the disease is glioblastoma.