Subclonal IDH mutation appears to occur across all WHO grades, and no significant difference was identified in the gender, age, grade, O-6-methylguanine-DNA methyltransferase (MGMT) promoter methylation frequency, or level of overall CNV between subclonal and clonal IDH-mutant astrocytoma cohorts or in grade-for-grade analysis (Table 2). The gene discussed is IDH1; the disease is astrocytoma (excluding glioblastoma).