A still poorly defined role of IFITM proteins in obesity development was suggested by the phenotype of mice lacking all five of the Ifitm genes, which develop an obese and metabolic syndrome phenotype related to hyperphagia, leptin resistance, and abnormal neuropeptide production, inflammatory status and microglia status in the hypothalamus [54]. The gene discussed is LEP; the disease is obesity due to melanocortin 4 receptor deficiency.