A compound attribute that is the ratio of amount of cathepsin Z (human) in blood to amount of sphingomyelin phosphodiesterase (human) in blood. The trait is Ontology of Biological Attributes entry OBA_2054628 (CTSZ/SMPD1 protein level ratio in blood). Also known as: the ratio of amount of cathepsin Z (human) in blood to amount of sphingomyelin phosphodiesterase (human) in blood.