 - Autoimmune disease: patients with a history of inflammatory bowel disease, including ulcerative colitis and Crohns disease, are excluded from this study, as are patients with a history of symptomatic disease e.g., rheumatoid arthritis, systemic progressive sclerosis scleroderma, systemic lupus erythematosus, autoimmune vasculitis e.g., Wegeners granulomatosis; central nervous system CNS or motor neuropathy considered of autoimmune origin e.g. Guillain-Barre syndrome and myasthenia gravis, multiple sclerosis 