PDE1C and obesity due to melanocortin 4 receptor deficiency: In the process of integrating multi-omics correlation analysis, we identified a set of biomarkers with well-interconnected networks implicated in obesity, such as BPIFA1, BPI, SAA1, PDE1C, Deoxycholic acid, Phthalic anhydride, DL-Alanine, p_Firmicutes, g_Intestinimonas, and g_Turicibacter.