GAD2 and paraneoplastic neurologic syndrome: In a retrospective study of 116 SCLC patients, among those 71 patients who presented with PNS, only 4 had seizures, and 16 had positive GAD65 Abs in serum; among those 45 patients who did not present with PNS, GAD65 Ab was also the most common type of neural autoantibodies, with 14 having it.[23] Therefore, GAD65 Ab is frequently positive in SCLC patients, and is likely associated with PNS in SCLC.