NRG4 and obesity due to melanocortin 4 receptor deficiency: Taken together, Nrg4 performed better for predicting various metabolic disorders when compared to other well-recognized molecules that serve as feasible biomarkers, such as adiponectin, homocysteine, and 25-hydroxy vitamin D. These outcomes emphasize that Nrg4 could be a potential biomarker for the occurrence of obesity-related metabolic diseases, but also highlighted the association between low Nrg4 levels and worse visual outcomes and risk of concurrent MetS.