We injected [2-13C]-fructose into the intraperitoneal cavity of wildtype or GLUT5-deficient P7 neonates born to and nursed by dams on HF diet or control diet 15 min prior to analysis (Fig. 3a), which allowed us to accurately measure fructose metabolism in the CNS while limiting the potential confound of fructose conversion in the small intestine or liver35. The gene discussed is SLC2A5; the disease is hydrops fetalis.