PTPRF/SDC1 protein level ratio in blood (OBA_2053219, an Ontology of Biological Attributes entry) can be described as follows. A compound attribute that is the ratio of amount of receptor-type tyrosine-protein phosphatase F (human) in blood to amount of syndecan-1 (human) in blood. Also known as: the ratio of amount of receptor-type tyrosine-protein phosphatase F (human) in blood to amount of syndecan-1 (human) in blood.