Because fatty acid oxidation is closely related to the production of mitochondrial ROS (Rosca et al., 2012; Cortassa et al., 2017), SIRT4 modulation of fatty acid metabolism can reduce high circulating levels of free fatty acids but unfortunately increase ROS production in obese patients with nonalcoholic fatty liver disease (Tarantino et al., 2014). The gene discussed is SIRT4; the disease is metabolic dysfunction-associated steatotic liver disease.