Obesity is closely related to IR, and most obese experimental animals showed impaired insulin response (Al-Massadi et al., 2019; Rodrigues et al., 2019; Zhang F. et al., 2020), while some experimental results demonstrated that FINS concentration in mice fed with a high-fat diet did not change significantly (Hanning et al., 2019). The gene discussed is INS; the disease is obesity due to melanocortin 4 receptor deficiency.