The amount of a tumor necrosis factor receptor superfamily member 9 (human) when measured in cerebrospinal fluid. The trait is level of tumor necrosis factor receptor superfamily member 9 (human) in cerebrospinal fluid (OBA_2058528, an Ontology of Biological Attributes term). Also known as: cerebrospinal fluid tumor necrosis factor receptor superfamily member 9 (human) amount.