The ever growing number of well characterized species-and sex-specific mechanisms of toxicity and carcinogenicity in rodents that have no comparison to and thus no relevance for humans, e.g. the α2u-globulin nephropathy/carcinogenesis [2], sodium-glucose linked transporter (SGLT) inhibitor mediated renal carcinogenesis in mice or rats [3], D-amino acid oxidase (DAAO) droplet nephropathy in male and female rats [4] etc. are testimony of the problems associated with using in vivo rodent bioassays to understand mechanisms of toxicity and the extrapolation of potential risk to humans. Here, DAO is linked to kidney disorder.