Previous studies have estimated tumor cell purity and determined the TCF containing specific mutations extrapolated from genomic data using more complicated formulas establishing the expected and observed VAF for each identified mutation.24,27,48–50 Here, we opted for a simplified method of estimating the TCF with IDH1 mutation, ie, comparison of the IDH1 VAF with the VAF of other known pathogenic mutations present in the same tumor sample (TP53 or ATRX). The gene discussed is IDH1; the disease is neoplasm.