Liu et al. found that multifocal glioblastomas had no IDH1, ATRX, or PDGFRA mutations compared with solitary glioblastomas and were significantly associated with the mesenchymal subtype [8]; Abou-El-Ardat et al. investigated its comprehensive molecular characterization and they found the high frequency of alterations in the 3 GBM core pathways: RTK/PI3K, p53, and RB regulatory pathways, which resemble primary GBMs, suggesting that multifocal glioblastomas develop through parallel genetic evolution [5]. The gene discussed is RB1; the disease is glioblastoma.