Anti‐GD1a ganglioside antibodies in peripheral motor syndromes

High titers of anti‐GD 1a antibodies have been found in patients with Guillain‐Barŕe syndrome or motor neuropathy. To determine the possible diagnostic relevance of these antibodies, we measured serum anti‐GD 1a IgG and IgM antibodies by enzyme‐linked immunosorbent assay in 195 patients with different motor syndromes and in 335 control subjects. Moderately high antibody titers (I/ 1,280‐1/5,120) were occasionally found in patients with chronic inflammatory demyelinating polyneuropathy (5%), multifocal motor neuropathy (18%), lower motor neuron disease (3.8%), or amyotrophic lateral sclerosis (1.8%) and in immunological control subjects (1.2%), while titers of 1/20,480 or higher were only found in 2 patients with Guillain‐Barri! syndrome (IgG in both) and 2 with motor neuropathy and IgMλ monoclonal gam‐mopathy improving with immunotherapy. In both motor neuropathy patients and the Guillain‐Barŕe syndrome patient who were retested during recovery, anti‐GD 1a titers decreased concomitantly with clinical improvement. High anti‐GD 1a antibody titers may be found in several motor syndromes but only markedly increased anti‐GD 1a titers are strictly associated with potentially treatable dysimmune neuropathies.