2011) and AQP9 is a specific glycerol transport channel in the liver. Hepatic AQP9 facilitates uptake of glycerol for synthesis of glucose and triglycerides thus involved in the pathogenesis of obesity and diabetes. Gene expression of AQP9 in the liver is up‐regulated in streptozotocin‐induced diabetic rats (Carbrey et al. 2003) and mice (Kuriyama et al. 2002), as well as in diet‐induced obese mice (Hirako et al. 2016). The gene discussed is AQP9; the disease is obesity due to melanocortin 4 receptor deficiency.