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This study identifies anti-CD320 autoantibodies as a novel biomarker in idiopathic myelopathy (IM), linked to central nervous system (CNS) vitamin B12 deficiency. The presence of these autoantibodies corresponds with distinct clinical features, a unique MRI pattern, and metabolic evidence of impaired vitamin B12 transport. Vitamin B12 supplementation with or without immunosuppression resulted in clinical improvement in most treated patients, suggesting potential therapeutic avenues.
