NRG4 and obesity due to melanocortin 4 receptor deficiency: To support this notation, cross-sectional and case-control studies conducted by Wang et al. [50] and Tutunchi et al. [51] found that low serum Nrg4 levels were inversely correlated with obesity indices (BMI, WC, and WHtR) and glucose and lipid metabolic indices (TG, FPI, and HOMA-IR) in children and adults with NAFLD, respectively.