Eleanor Bishop et al. (Bishop et al., 2022) identified arginine-assisted trophic features in pediatric high-grade and low-grade gliomas, ventricular meningiomas, and medullo-blastomas, with a high percentage of tumors in pHGG samples deficient in OTC, ASS1, and ASL, suggesting potential sensitivity to arginine depletion therapy. The gene discussed is ASS1; the disease is blastoma.