Additionally, new functions of leptin in milk (Palou et al., 2018) and amniotic fluid (Yau-Qiu et al., 2020) regardig early metabolic programming and metabolic health have also been reported in recent studies, in which animals showed long-term beneficial effects of leptin treatment against metabolic disease when leptin was administered during the lactation period. The gene discussed is LEP; the disease is metabolic disease.