A compound attribute that is the ratio of amount of mediator of RNA polymerase II transcription subunit 18 (human) in blood to amount of F-box-like/WD repeat-containing protein TBL1X (human) in blood. The trait is MED18/TBL1X protein level ratio in blood (OBA_2053796, an Ontology of Biological Attributes term). Also known as: the ratio of amount of mediator of RNA polymerase II transcription subunit 18 (human) in blood to amount of F-box-like/WD repeat-containing protein TBL1X (human) in blood.