SPAG1 and central nervous system cancer: Thirteen major discriminators between low- and high-grade tumor samples were found: expression levels of HCD2, HBA and HBD were strongly up-regulated in high-grade gliomas, whereas CRYAB_b, IPYR, TPIS, PEA15, PSD13, GFAP, PHP14, 6PGL, KCRB, IDH3A had higher expression in low-grade than high-grade tumors (component PC2, Figure 3A, right).