Seroconversion of anti-GM1 antibodies in patients with amyotrophic lateral sclerosis

Elevated titers of anti-GM1 antibodies, particularly those of the IgM class that recognize the Gal β(1–3)Gal-NAc epitope (GM1), are occasionally detected in patients with pure motor syndromes including multifocal motor neuropathies and motor neuron diseases (MNDs).1 Although circumstantial evidence might implicate these antibodies in MND pathogenesis,2,3⇓ the administration of immunomodulatory therapies in anecdotal cases of MND with anti-GM1 antibodies has produced controversial or disappointing results.4,5⇓ Thus, their presence in patients with ALS constitutes a clinical conundrum: Are they the outcome of initial damage to peripheral motor neurons? Do they contribute to the neuronal damage? Is their presence a marker for a small subpopulation of patients who present with motor neuron syndrome but actually do not have MND? We have recently encountered an ALS patient who developed anti-GM1 antibodies during her disease course. This prompted us to retrospectively study all files of ALS patients hospitalized in our institute within the years 1989 to 2003 for the presence of examinations of anti-GM1 …