Demonstrating this negative association, we observed a significantly lower proportion of signature 1 mutations in IDH1 p.R132H mutant rather than wild-type brain lower grade glioma (P < 0.0001) and glioblastoma multiforme (P < 0.001; Fig 4A) by two-sided Mann Whitney U-Test. This evidence concerns the gene IDH1 and glioblastoma.