The amount of a ELKS/Rab6-interacting/CAST family member 1 (human) when measured in cerebrospinal fluid. The trait is level of ELKS/Rab6-interacting/CAST family member 1 (human) in cerebrospinal fluid (OBA_2059644, an Ontology of Biological Attributes term). Also known as: cerebrospinal fluid ELKS/Rab6-interacting/CAST family member 1 (human) amount.