Lai and colleagues established whole-body galactose oxidation (WBGO) as a robust, noninvasive, and specific method to assess the in vivo pharmacokinetic and pharmacodynamic parameters of two experimental gene-based therapies (GALT mRNA and AAVrh10-GALT gene replacement) that aimed to restore GALT activity in a mouse model of Galactosemia. Here, GALT is linked to classic galactosemia.