A compound attribute that is the ratio of amount of mothers against decapentaplegic homolog 1 (human) in blood to amount of TBC1 domain family member 23 (human) in blood. The trait is OBA_2055654 (SMAD1/TBC1D23 protein level ratio in blood). Also known as: the ratio of amount of mothers against decapentaplegic homolog 1 (human) in blood to amount of TBC1 domain family member 23 (human) in blood.