GAD2 and stiff-person syndrome: A retrospective analysis of 121 patients with SPS spectrum disorder further confirmed this link: 41.3 % (50/121) had classic SPS, 65.4 % (34/52) of whom had concurrent systemic autoimmune diseases, and 86.5 % (45/52) exhibited elevated GAD65 antibody levels (Martinez-Hernandez et al., 2016).