A compound attribute that is the ratio of amount of cytochrome c oxidase subunit 5B, mitochondrial (human) in blood to amount of frataxin, mitochondrial (human) in blood. The trait is COX5B/FXN protein level ratio in blood (Ontology of Biological Attributes id OBA_2053851). Also known as: the ratio of amount of cytochrome c oxidase subunit 5B, mitochondrial (human) in blood to amount of frataxin, mitochondrial (human) in blood.