Methods and genetic sequences are described for use in determining the diagnosis, subtype, prognosis, and disease course of high-grade gliomas, such as glioblastoma multiforme. One such method includes determining increased expression of at least one gene on a chromosome segment in cells of the glioma, the segment being 17:57,851,812-17:57,973,757; 7:127,892,509-7:127,947,649; 12:33,854-12:264,310; or 19:33,329,393-19:35,322,055; and estimating, based on the expression, a predicted length of survival, a probability of survival, or a predicted response to a therapy for the glioma.