There are many results that support the role of resistin as an important pathogenic factor in obesity and related disorders: higher serum level of resistin in the various murine genetic or diet-induced model of obesity [5]; positive correlation between the resistin serum level, gene expression level and BMI, degree of insulin resistance [8]; down-regulation by Rosiglitazone treatment [9], [10]. The gene discussed is RETN; the disease is obesity due to melanocortin 4 receptor deficiency.