BTLA and gastroesophageal junction adenocarcinoma: Rs1982809 is a functional single nucleotide polymorphism (SNP) that affects BTLA 3′-UTR activity and BTLA expression, and has been found to be associated with a higher incidence of renal cell carcinoma (57), chronic lymphocytic leukemia (58) and esophagogastric junction adenocarcinoma (59).