XKR4 (XK-related protein 4) is a protein-coding gene located on human chromosome 8q12.2 that belongs to the XK family of membrane transporters . The encoded protein is predicted to function as a membrane transporter involved in the translocation of phospholipids and other substrates, though its precise physiological role remains incompletely characterized . XKR4 is widely expressed, with highest levels detected in the brain, testis, and adipose tissues . Genetic variants in XKR4 have been robustly associated with body weight regulation, obesity risk, and fat distribution in genome-wide association studies, and it has also been implicated in satiety signaling and feeding behavior . Additionally, mutations in this gene have been linked to altered adipogenesis and energy homeostasis, making it a relevant target for metabolic research .