The amount of a Phosphatidylcholine (O-16:0_22:5) when measured in blood serum. The trait is level of Phosphatidylcholine (O-16:0_22:5) in blood serum (Ontology of Biological Attributes entry OBA_2045117). Also known as: blood serum Phosphatidylcholine (O-16:0_22:5) amount.