However, Shirahata et al., Appay et al., and Yoda et al. proposed using CDKN2A/B alone as a molecular marker for grade 4 IDH-mutant astrocytoma, determined by a number of methods, including methylation, SNP array, and NGS [11,12,13]. The gene discussed is CDKN2A; the disease is astrocytoma (excluding glioblastoma).