HMBS/UBAC1 protein level ratio in blood (OBA_2053060, an Ontology of Biological Attributes term) can be described as follows. A compound attribute that is the ratio of amount of porphobilinogen deaminase (human) in blood to amount of ubiquitin-associated domain-containing protein 1 (human) in blood. Also known as: the ratio of amount of porphobilinogen deaminase (human) in blood to amount of ubiquitin-associated domain-containing protein 1 (human) in blood.