Serum samples were obtained from 249 sero-positive (SP) MG and 70 sero-negative (SN) MG patients and from 136 patients with other neurological or immunological diseases (10 Lambert-Eaton myasthenic syndrome, 10 polymyositis, 15 multiple sclerosis, 5 spinal progressive muscular atrophy, 5 chronic inflammatory demyelinating polyneuropathy, 28 ALS, 10 epilepsy, 15 progressive muscular dystrophies, 15 thyroiditis, 10 type 1 diabetes mellitus, and 13 rheumatoid arthritis).