Multiple studies have also indicated that IDH-mutant lower-grade astrocytomas have significantly lower overall copy number variation (CNV; also referred to as copy number alteration, CNA), expressed as the sum of all gains and losses spread in a seemingly random pattern without regions of definitive “molecular signature” across the entire genome, compared to their IDH-mutant GBM counterparts [52,67] or IDH-wildtype lower-grade astrocytomas and GBMs [52]. This evidence concerns the gene IDH1 and glioblastoma.