GAD2 and stiff-person syndrome: GAD65 is a well-recognized major autoantigen in type 1 diabetes mellitus (DM1), and recent studies have shown that high GAD65 antibody serum levels are associated with neurological disorders such as stiff-person syndrome (SPS), cerebellar ataxia, epilepsy, and paraneoplastic neurological syndrome (PNS) [3–6].