FTO and obesity due to melanocortin 4 receptor deficiency: This systematic literature review investigates the role of six obesity-associated genes, including fat mass and obesity-associated (FTO), FAS apoptosis inhibitory molecule 2 (FAIM2), Niemann-Pick disease type C1-like 1 (NPC1), glucosamine-6-phosphate deaminase 2 (GNPDA2), melanocortin-4 receptor (MC4R), and brain-derived neurotrophic factor (BDNF) in the context of MS.<h4>Methods</h4>A literature search was executed using Embase, Scopus, Cochrane, Web of Science, and PubMed databases from inception to July 2024.