A compound attribute that is the ratio of amount of Thy-1 membrane glycoprotein (human) in blood to amount of tumor necrosis factor receptor superfamily member 21 (human) in blood. The trait is THY1/TNFRSF21 protein level ratio in blood (OBA_2053048). Also known as: the ratio of amount of Thy-1 membrane glycoprotein (human) in blood to amount of tumor necrosis factor receptor superfamily member 21 (human) in blood.