Ontology of Biological Attributes term OBA_2055717 (CA13/GRAP2 protein level ratio in blood) can be described as follows. A compound attribute that is the ratio of amount of carbonic anhydrase 13 (human) in blood to amount of GRB2-related adapter protein 2 (human) in blood. Also known as: the ratio of amount of carbonic anhydrase 13 (human) in blood to amount of GRB2-related adapter protein 2 (human) in blood.