RAET1E (retinoic acid early transcript 1E) encodes ULBP4, a transmembrane glycoprotein that functions as a ligand for the NKG2D activating receptor on natural killer (NK) cells and T cells 12. The protein contains α1 and α2 domains but lacks the α3 domain and does not associate with β2-microglobulin 2. RAET1E binding to NKG2D mediates NK cell cytotoxicity against infected, tumorigenic, and damaged cells, playing a crucial role in innate immunity 13. The gene exhibits significant allelic polymorphism, with at least 15 known alleles showing variations in promoter regions, exons, and 3' UTR sequences that may affect expression levels through altered transcription factor binding sites and microRNA interactions 14. Polymorphism patterns vary among ethnic populations, with different allele frequencies observed in Thai and South American Indian populations 253. RAET1E shows strong linkage disequilibrium with other RAET1 genes, particularly RAET1G, forming conserved haplotypes 5. The gene has clinical relevance as a prognostic marker in lung adenocarcinoma and is associated with immune cell infiltration patterns in various diseases including Alzheimer's disease 67.