A compound attribute that is the ratio of amount of butyrophilin subfamily 2 member A1 (human) in blood to amount of ephrin type-A receptor 1 (human) in blood. The trait is BTN2A1/EPHA1 protein level ratio in blood (OBA_2053166, an Ontology of Biological Attributes term). Also known as: the ratio of amount of butyrophilin subfamily 2 member A1 (human) in blood to amount of ephrin type-A receptor 1 (human) in blood.