The amount of a izumo sperm-egg fusion protein 1 (human) when measured in cerebrospinal fluid. The trait is level of izumo sperm-egg fusion protein 1 (human) in cerebrospinal fluid (OBA_2059720, an Ontology of Biological Attributes identifier). Also known as: cerebrospinal fluid izumo sperm-egg fusion protein 1 (human) amount.