TGFB1 and glioma: We also compared the serum concentrations of TGF-β1 in patients with high-grade glial tumors carrying the T/T-genotype with the controls, and there was a significant elevation in the patients (12.20 ± 4.43 ng/mL) vs. the controls (8.06 ± 4.07 ng/mL, p = 0.036, t-test).