A compound attribute that is the ratio of amount of R-spondin-1 (human) in blood to amount of R-spondin-3 (human) in blood. The trait is Ontology of Biological Attributes term OBA_2053157 (RSPO1/RSPO3 protein level ratio in blood). Also known as: the ratio of amount of R-spondin-1 (human) in blood to amount of R-spondin-3 (human) in blood.