IDH1 and central nervous system cancer: Among the intratumoral heterogeneity for CDKN2A/B HD, Vega et al (28) mentioned in their study that they evaluated intratumoral heterogeneity with the help of DNA methylation profile in 39 cases of glioma and meningioma, and they reported that they detected intratumoral heterogeneity in CDKN2A/B HD in 1 of the 2 IDH-mutant astrocytomas included in the study, and this may lead to incorrect grading of IDH-mutant astrocytomas.