IDH1 and central nervous system cancer: For instance, the mean tumor purity based on histology in meningioma was 84% with a variance of 0.02 compared to IDH-mutant gliomas (mean purity 69%, variance 0.1, p = 9.096e−06) and glioblastoma IDH-wildtype (mean purity 76%, variance 0.05, p = 0.00836).