BTN2A1/SIGLEC1 protein level ratio in blood (Ontology of Biological Attributes id OBA_2053172) can be described as follows. A compound attribute that is the ratio of amount of butyrophilin subfamily 2 member A1 (human) in blood to amount of sialoadhesin (human) in blood. Also known as: the ratio of amount of butyrophilin subfamily 2 member A1 (human) in blood to amount of sialoadhesin (human) in blood.