The amount of a serine/threonine-protein phosphatase PP1-gamma catalytic subunit when measured in blood serum. The trait is level of serine/threonine-protein phosphatase PP1-gamma catalytic subunit in blood serum (Ontology of Biological Attributes entry OBA_2042999). Also known as: blood serum serine/threonine-protein phosphatase PP1-gamma catalytic subunit amount.