Antibodies against GAD are found in which neurologic condition?

Antibodies against glutamic acid decarboxylase (GAD) are specifically associated with Stiff-Person syndrome, a rare neurological disorder characterized by muscle stiffness and spasms. GAD is an enzyme crucial for the synthesis of the neurotransmitter gamma-aminobutyric acid (GABA), which is important for inhibitory neurotransmission in the central nervous system. The presence of GAD antibodies indicates an autoimmune attack on the cells that produce this enzyme, leading to the symptoms observed in Stiff-Person syndrome.

This condition often coexists with other autoimmune diseases, including type 1 diabetes and autoimmune encephalitis, further supporting the role of GAD antibodies in autoimmune mechanisms affecting the nervous system. In contrast, while other conditions listed may involve autoimmune processes, they are not specifically associated with GAD antibodies and have distinct pathophysiological mechanisms and antibodies when present.