GAD1 and stiff-person syndrome: <h4>Introduction</h4>Stiff-person syndrome (SPS) is a rare neurological disorder that causes progressive muscle rigidity, gait disturbances, and functional impairment; type 1 is autoimmune, with positive anti-GAD antibodies (Ab), while type 2 is paraneoplastic and associated with antiamphiphysin Ab.<h4>Case presentation</h4>A 41-year-old man with a silent medical history presented with stiffness and functional impairment; after numerous rheumatological and neurological investigations, he was diagnosed with SPS, with evidence of high titer anti-GAD Ab.