In this biplot representation most genes contributed substantially to the formation of the factorial horizontal axis 1, which provides a clear distinct structure between GBM and both DA + AA samples, the most discriminatory genes being the ETNPPL, SH3GL2, GABRG2, SPX, DPP10, TOP2A, SHOX2, IGF2BP3, ANXA1, VEGFA and CHI3L1 genes. The gene discussed is SPX; the disease is glioblastoma.