A compound attribute that is the ratio of amount of platelet glycoprotein VI (human) in blood to amount of semaphorin-4D (human) in blood. The trait is Ontology of Biological Attributes id OBA_2053429 (GP6/SEMA4D protein level ratio in blood). Also known as: the ratio of amount of platelet glycoprotein VI (human) in blood to amount of semaphorin-4D (human) in blood.