CTXN2 (cortexin 2) is a gene located on chromosome 15 that appears to have roles in skin pigmentation and potentially in sleep-wake regulation. In skin biology, CTXN2 variants, specifically rs12913316, are associated with human skin color variation and are identified as major contributors to skin pigmentation phenotypes, explaining a portion of observed variance in melanin production across populations 1. The gene can be involved in genomic deletions associated with connective tissue disorders; a 542 kb deletion spanning the entire FBN1 gene encompassed CTXN2 alongside other genes (SLC24A5, MYEF2, SLC12A1, DUT) in patients with Marfan syndrome presenting with aortopathy 2. In sleep physiology, CTXN2 expression is downregulated in individuals with insomnia disorder compared to healthy controls, suggesting a potential role in sleep homeostasis 3. The downregulation of CTXN2 in insomnia patients may be associated with broader transcriptomic changes linked to inflammation, immune response, and mitochondrial dysfunction in sleep disorders. However, the precise molecular mechanisms by which CTXN2 regulates pigmentation or sleep remain incompletely characterized, and further functional studies are needed to elucidate its specific biochemical roles.