The amount of a protein phosphatase 1 regulatory subunit 42 (human) when measured in cerebrospinal fluid. The trait is level of protein phosphatase 1 regulatory subunit 42 (human) in cerebrospinal fluid (OBA_2059509, an Ontology of Biological Attributes entry). Also known as: cerebrospinal fluid protein phosphatase 1 regulatory subunit 42 (human) amount.