Additional evidence in both mammalian and teleost fishes suggest leptin may stimulate energy expenditure through carbohydrate catabolism as the hormone promotes hepatic glycogenolysis and peripheral glucose uptake (6–8), while functional leptin receptor (lepr) ablation in zebrafish drives β-cell hyperplasia, hyperglycemia, and an impairment of glucose control (9). The gene discussed is LEPR; the disease is Hyperglycemia.