Amyotrophic lateral sclerosis associated with IgG anti-GalNAc-GD1a antibodies

A variety of immunological abnormalities have been reported in some patients with amyotrophic lateral sclerosis (ALS). It has been postulated that a disturbance of immunoregulation may play a role in the degeneration of motor neurons in ALS. We describe a 62-year-old man with a 9-month history of slowly progressive muscular weakness and atrophy of the upper and lower extremities and dysarthria. Neurological examinations revealed weakness and atrophy with fasciculation in the skeletal muscles including the face and tongue. In the limbs, distal muscles were affected predominantly. Electromyography showed chronic neurogenic changes with denervation potentials. Serum antibody testing demonstrated an increased titer of anti-N-acetylgalactosaminyl GD1a (GalNAc-GD1a) antibodies (IgG ×160; normal, less than ×40). The patient was treated with intravenous immunoglobulin (IVIg) therapy which was repeated two times at an interval of 2 months. However, the response to IVIg was negligible. To the authors’ knowledge, this is the first report on ALS, in which the patient had anti-GalNAc-GD1a IgG antibody.