A compound attribute that is the ratio of amount of fractalkine (human) in blood to amount of ephrin type-B receptor 6 (human) in blood. The trait is CX3CL1/EPHB6 protein level ratio in blood (Ontology of Biological Attributes identifier OBA_2054631). Also known as: the ratio of amount of fractalkine (human) in blood to amount of ephrin type-B receptor 6 (human) in blood.