Cause, Development, and Progression of Stiff-Person Syndrome

This study will explore the role of various immune factors involved in producing the disease symptoms in stiff-person syndrome (SPS) and follow disease progression in patients. SPS is a progressive disease in which unexpected noises, touches or stressful events set off muscle spasms and stiffness. It is thought to be an autoimmune disease in which the body produces antibodies that attack certain healthy tissues. A better understanding of the disease may help researchers design new therapies. Patients of any age with SPS may be eligible for this study, except those who: * Lack of serum anti-GAD antibodies * Have very advanced disease that precludes traveling * Have severe cardiovascular, renal, or other end-organ-disease states Candidates will be screened with a medical history and physical and neurological examinations to confirm the diagnosis of SPS. After screening, those enrolled in the study will be followed at the NIH Clinical Center every 6 months for 2 years (months 6, 12, 18, and 24) to have the following tests and procedures: * Physical and neurological examinations and review of symptoms (every visit) * Blood draw for routine tests and for research studies (every visit) * Stiffness assessment (every visit) - Patients are asked a series of questions about their stiffness, which physicians rate according to the number of stiff areas (e.g., 0-no stiff areas; 1-stiffness of the lower trunk; 2-stiffness of the upper trunk, etc.). * Lymphapheresis (at the beginning of the study and at 12 months) - This is a procedure for collecting large quantities of white blood cells. A needle is placed in a vein in the arm. Blood flows from the vein through a plastic tube (catheter) into a machine that spins the blood, separating it into its components. The white blood cells (lymphocytes) are removed, and the rest of the blood-plasma, red cells and platelets-is returned to the body through a second needle placed in the other arm. * Electrophysiologic studies - These stud