CD40LG and amyotrophic lateral sclerosis: IgM anti-ganglioside GM1 antibodies are present in approximately half of patients with MMN (30–80% depending on series).30,31 However, they have also been associated with other immune-mediated neuropathies, non-immune-related neuropathies and even patients with ALS.32–34 Therefore, anti-GM1 antibodies are diagnostically helpful but cannot be relied upon absolutely.