To confirm the correlation between TMEFF2 promoter methylation and expression in gliomas, we queried a dataset from TCGA and observed a significant negative correlation (Spearman’s r = – 0.47, P < 0.001) between the TMEFF2 promoter methylation level and mRNA expression in glioma (Fig. 2c). The gene discussed is TMEFF2; the disease is central nervous system cancer.