CA13/HARS1 protein level ratio in blood (Ontology of Biological Attributes term OBA_2055718) can be described as follows. A compound attribute that is the ratio of amount of carbonic anhydrase 13 (human) in blood to amount of histidine--tRNA ligase, cytoplasmic (human) in blood. Also known as: the ratio of amount of carbonic anhydrase 13 (human) in blood to amount of histidine--tRNA ligase, cytoplasmic (human) in blood.