A compound attribute that is the ratio of amount of glutathione-specific gamma-glutamylcyclotransferase 2 (human) in blood to amount of thiopurine S-methyltransferase (human) in blood. The trait is Ontology of Biological Attributes identifier OBA_2055561 (CHAC2/TPMT protein level ratio in blood). Also known as: the ratio of amount of glutathione-specific gamma-glutamylcyclotransferase 2 (human) in blood to amount of thiopurine S-methyltransferase (human) in blood.