A compound attribute that is the ratio of amount of cytotoxic and regulatory T-cell molecule (human) in blood to amount of T-lymphocyte surface antigen Ly-9 (human) in blood. The trait is CRTAM/LY9 protein level ratio in blood (Ontology of Biological Attributes entry OBA_2054510). Also known as: the ratio of amount of cytotoxic and regulatory T-cell molecule (human) in blood to amount of T-lymphocyte surface antigen Ly-9 (human) in blood.