Additional loss of chromosome arm 10q is seen in over 75% of IDH-wild-type glioblastoma and usually spans the PTEN locus at 10q23.31, and in 60% of IDH-mutant glioblastoma cases, the most commonly deleted region being 10q25-qter, encompassing the FGFR2 and DMBT1 loci [4]. The gene discussed is IDH1; the disease is glioblastoma.