The present invention identifies a gene whose gene product provides a protective effect against neurological disorders or neuronal injuries. Further, the invention provides methods for diagnosing or assessing an individual's susceptibility to a neuronal injury such as stroke. Also provided are therapeutic methods for treating patients, and methods for prophylactically treating individuals susceptible to various neurological disorders or neuronal injuries. Additionally, the invention describes screening methods for identifying agents that can be administered to treat individuals that have suffered or are at risk to suffer such disorders or injuries.