The amount of a carnitine O-palmitoyltransferase 1, muscle isoform when measured in blood serum. The trait is level of carnitine O-palmitoyltransferase 1, muscle isoform in blood serum (Ontology of Biological Attributes identifier OBA_2041126). Also known as: blood serum carnitine O-palmitoyltransferase 1, muscle isoform amount.