GDF15 and glioma: Consequently, we performed an analysis of the molecular group related to the embryonic/germ cell cycle (including LIF, STAT3, PRDM1, IFITM3, ACVR1, CXCR4, WNT5A, ROR2, ITGB1, POU5F1, GDF15 and BMP8B) (Additional file 1: Table S7) to determine whether we could identify glioma outcomes more accurately based on the germ cell-related molecular group than based on the histologic class.