A compound attribute that is the ratio of amount of amyloid-beta precursor protein (human) in blood to amount of nidogen-1 (human) in blood. The trait is APP/NID1 protein level ratio in blood (Ontology of Biological Attributes id OBA_2053915). Also known as: the ratio of amount of amyloid-beta precursor protein (human) in blood to amount of nidogen-1 (human) in blood.