At the individual level, several IGCs that were highly enriched in GSCs had very low or absent expression in bulk GBM tumor samples (e.g. GRIK4, SCN8A, KCNC3, ASIC3, and HCN3), suggesting that these candidates may be the most therapeutically tractable for specifically targeting GSCs within the tumor. The gene discussed is GRIK4; the disease is neoplasm.