A compound attribute that is the ratio of amount of plexin-A4 (human) in blood to amount of protein sprouty homolog 2 (human) in blood. The trait is Ontology of Biological Attributes entry OBA_2053523 (PLXNA4/SPRY2 protein level ratio in blood). Also known as: the ratio of amount of plexin-A4 (human) in blood to amount of protein sprouty homolog 2 (human) in blood.