Comparing the expression levels of the nine HPGs between tumor samples in the TCGA dataset and normal samples in the GTEx dataset, we found that although CASP4, TP63, and PLCG1 were considered risk genes, the expression of these genes was elevated in normal brain tissue compared to the tumor group (Figs. 4A–4C) (P < 0.001). This evidence concerns the gene PLCG1 and neoplasm.