We then cloned different previously described gRNAs6,23,24 targeting tumors suppressor genes (TSGs) frequently altered in high-grade gliomas: TP53, CDKN2A, and PTEN (mutated or deleted in 30, 62, and 41% GBM patients, respectively) (Supplementary Fig. 2a). The gene discussed is CDKN2A; the disease is glioblastoma.