Like all cancers, Glioblastoma multiforme (GBM), the most common and deadly primary brain tumor, is an evolutionary disease: mutations in glial cell lineages change gene expression, leading to tumor growht and metastatic disease. How genomic changes influence gene expression is not well understood. Expression quantitative trait loci, or eQTLs, are significant, predictive associations between (i) a single nucleotide polymorphism somewhere in the genome, and (ii) the expression level of some gene product, measured by microarray, RNA-seq, or some other method [1]. eQTLs have been found to explain some 3% of the gene expression variation in the TCGA breast cancer dataset [2]. Here, we systematically look for eQTLs in the TCGA GBM dataset.