the capacity to secrete antigens of the ABO blood group in saliva and other body fluids, controlled by a pair of allelic genes designated Se and se (or S and s), with the Se phenotype dominant to se; the saliva of genotypes SeSe and Sese contains the blood group substances A, B, or H found in their erythrocytes; the saliva of nonsecretors (genotype sese) contains no blood group substance; tests for ABH secretion are useful in genetic linkage and population studies; the secretor phenomenon is also closely associated with the Lewis blood group.