Despite their different cellular origins, statistically significant positive correlations were observed between the expression levels of DJ-1, GDF15, and MFGE8 and both tumour grade and the Ki-67 proliferation index (Ki-67 Pi) in both glioma and meningioma cases, indicating that higher gene expression is associated with increased tumour aggressiveness in both tumour types. This evidence concerns the gene GDF15 and glioma.