A compound attribute that is the ratio of amount of roundabout homolog 2 (human) in blood to amount of scavenger receptor class F member 2 (human) in blood. The trait is ROBO2/SCARF2 protein level ratio in blood (OBA_2053151, an Ontology of Biological Attributes entry). Also known as: the ratio of amount of roundabout homolog 2 (human) in blood to amount of scavenger receptor class F member 2 (human) in blood.