IDH1 and central nervous system cancer: In addition, genetic analysis of multiple biopsies, resections, and autopsy specimens within individual patients with diffuse glioma has demonstrated significant regional heterogeneity of chromosomal alterations and heterogeneity of specific epigenetic alterations (including MGMT promoter methylation), as well as mounting overall CNA levels in the recurrent tumor samples, an effect that was more pronounced and was more predictive of clinical behavior in IDH-mutant tumors than other glioma types, although this may be driven in part by treatment, including radiotherapy [133].