INS and obesity due to melanocortin 4 receptor deficiency: In KEGG pathway enrichment analysis, we found some pathways related to obesity or obesity-related complications, such as MAPK signaling pathway, PI3K-Akt signaling pathway, cAMP signaling pathway, mTOR signaling pathway, metabolic pathways, insulin signaling pathway, glycerophospholipid metabolism, fatty acid biosynthesis, fructose and mannose metabolism, type II diabetes mellitus, etc. MAPK signaling pathway plays a complex and important regulatory role in adipocyte differentiation [36].