The amount of a phosphatidylinositol 3-kinase regulatory subunit alpha (human) when measured in cerebrospinal fluid. The trait is level of phosphatidylinositol 3-kinase regulatory subunit alpha (human) in cerebrospinal fluid (OBA_2057545, an Ontology of Biological Attributes identifier). Also known as: cerebrospinal fluid phosphatidylinositol 3-kinase regulatory subunit alpha (human) amount.