2015). In agreement with this hypothesis, shRNA-mediated silencing of Aqp9 has alleviated nonalcoholic fatty liver disease (NAFLD) in a diet-induced rat model of obesity (Cai et al. 2013). In this study we have conducted a comprehensive phenotypic analysis of coisogenic Aqp9wt and Aqp9−/− mice, aiming for enhanced understanding of the metabolic role of AQP9 in mice on the C57BL/6 db/db genetic background, including its proposed role in TAG synthesis and NAFLD. The gene discussed is AQP9; the disease is metabolic dysfunction-associated steatotic liver disease.