Surprisingly, the endogenous increase of ω-3 PUFA levels in the hemizygous fat-1+/− mice did not result in prevention of HF diet-induced hepatic steatosis despite marked improvements of insulin resistance and glucose tolerance.23 This was unexpected given previous studies reporting that supplementation of marine ω-3 PUFA protects from hepatic fat accretion,25 and suggests a marked difference between the impacts of dietary vs endogenous ω-3 PUFA on hepatic steatosis. The gene discussed is FAT1; the disease is Hepatic steatosis.